Tutorial lesson: GCSE chemistry. Sample containing about 13113 words speech recorded in educational context

4 speakers recorded by respondent number C107

PS1UB Ag4 m (John, age 50, tutor) unspecified
PS1UC Ag1 m (Andrew, age 16, student) unspecified
FMRPSUNK (respondent W0000) X u (Unknown speaker, age unknown) other
FMRPSUGP (respondent W000M) X u (Group of unknown speakers, age unknown) other

1 recordings

  1. Tape 087501 recorded on 1993-04-09. Locationmerseyside: Liverpool ( Students home ) Activity: GCSE Chemistry Tutoring session

Undivided text

Unknown speaker (FMRPSUNK) [1] this weekend and the er That's [...]
Andrew (PS1UC) [...]
John (PS1UB) [2] That's alright good.
[3] ... So [...] saying today, we'll give the give all the acids alkalis and bases a bit of a rest
Andrew (PS1UC) [4] yes.
John (PS1UB) [5] erm look at some of the more general stuff.
[6] Now is there anything you want to look at?
Andrew (PS1UC) [7] Er
John (PS1UB) [8] Particularly where you've more or less got the idea of it but you think you just want to sort of tidy up a few details an
Andrew (PS1UC) [9] I don't think Nothing that to hand immediately, no. ...
John (PS1UB) [10] One of the things we were talking about last time was separating mixtures and solvents.
Andrew (PS1UC) [11] Yeah.
John (PS1UB) [12] Erm it's an obvious one but it's easy to miss.
[13] How do you separate sand and salt?
[14] I mean they won't say sand and salt, they'll say something which is insoluble and give it a horrible chemical name [laugh]
Andrew (PS1UC) [15] Yeah.
John (PS1UB) [16] And something which is soluble with another horrible [...] and you'll think Er I don't know.
[17] But just think just [...]
Andrew (PS1UC) [18] Mix it in with water and then filter it out.
John (PS1UB) [19] Yeah, just like sand and salt.
[20] They might say How do you make sure it'd pure?
[21] Well you you wash then one that's not soluble.
[22] Or they might say how would you get a sort of a clean dry version of it?
[23] So you know what to do for that.
Andrew (PS1UC) [24] Mm.
John (PS1UB) [25] Wash it and dry it.
[26] Erm ... I dunno.
[27] I mean things like that You're not gonna have any trouble with that, are you?
Andrew (PS1UC) [28] No.
John (PS1UB) [29] they represent different atoms.
[30] Which ones are mixtures an
Andrew (PS1UC) [31] Er ... That one's ... erm n Which one's mixtures, that's a mixture.
John (PS1UB) [32] That's well They're all the same.
Andrew (PS1UC) [33] Yeah.
John (PS1UB) [34] That's the black Filled in version is one type of atom and that's another
Andrew (PS1UC) [35] Yeah.
John (PS1UB) [36] type of atom, so how many types of atom are there in B?
Andrew (PS1UC) [37] One.
John (PS1UB) [38] So what's ... is that a mixture of
Andrew (PS1UC) [39] er no it's a
John (PS1UB) [40] No okay.
Andrew (PS1UC) [41] Element.
John (PS1UB) [42] Right, and this one.
[43] So
Andrew (PS1UC) [44] Is
John (PS1UB) [45] which ones are mixtures then?
Andrew (PS1UC) [46] Er ... that one.
John (PS1UB) [47] Okay.
[48] Any others?
Andrew (PS1UC) [49] Just looking er ... Can't th No there isn't.
John (PS1UB) [50] What about this one.
Andrew (PS1UC) [51] It's a compound isn't it?
[52] Cos they've bonded with each other.
John (PS1UB) [53] Okay ... [reading] Which diagram r represents a mixture of atoms? []
[54] Mm.
[55] that one, that one So you have to be careful what they mean there.
[56] The following list of substances, have a look at that.
[57] One point two.
Andrew (PS1UC) [58] [reading] Which metal is a liquid at room temperature and pressure? []
[59] Mercury.
John (PS1UB) [60] Okay.
Andrew (PS1UC) [61] [reading] Name the two elements present in common salt. []
[62] Sodium and chlorine.
John (PS1UB) [63] Great.
Andrew (PS1UC) [64] [reading] Name a non-metal present in oil. []
[65] ... Eh?
[66] Er Carbon.
John (PS1UB) [67] that's an awkward one, [...] Yeah good.
Andrew (PS1UC) [68] [reading] Which element is yellow in colour? []
[69] Sulphur.
[70] [reading] Name the element used in street lighting. []
[71] Sodium.
[72] Er [reading] Name a compound. []
[73] Er s ... compound er ...
John (PS1UB) [74] Well what was [...]
Andrew (PS1UC) [75] Sodium Chloride
John (PS1UB) [76] Great yeah.
[77] Read this [...]
Andrew (PS1UC) [78] [reading] Name a mixture. []
[79] Yeah.
John (PS1UB) [80] the should ask for the two elements present in common salt and they say Name a compound.
Andrew (PS1UC) [81] [reading] Name a mixture.
[82] [] er [whispering] [...] []
John (PS1UB) [83] Presumably they mean out of this lot.
Andrew (PS1UC) [84] Yeah, er ... Carbon dioxide.
[85] [...] mixture no.
[86] Er ... water, no that's a compound er
John (PS1UB) [87] You keep saying the answer actually.
[88] ... [whispering] Oxygen. []
Andrew (PS1UC) [89] Er
John (PS1UB) [90] What do you keep saying while your thinking [...]
Andrew (PS1UC) [91] Air.
John (PS1UB) [92] [laugh] Yeah okay.
[93] And wh what is air a mixture of then?
Andrew (PS1UC) [94] Er [laugh]
John (PS1UB) [95] Some of the things that are in it .
Andrew (PS1UC) [96] Er Nitrogen, oxygen, Carbon dioxide .
John (PS1UB) [97] Yeah yeah, yeah.
[98] Nitrogen and oxygen are the two big They're the two main ones and then anything else you can put.
[99] Carbon dioxide, good and then you get all the funny, little trace ... gases.
[100] Okay, ... What's this then?
Andrew (PS1UC) [...]
John (PS1UB) [101] Erm
Andrew (PS1UC) [102] Filtration [...] you know.
John (PS1UB) [...]
Andrew (PS1UC) [103] A liquid.
John (PS1UB) [104] So D
Andrew (PS1UC) [105] No
John (PS1UB) [106] Is ...
Andrew (PS1UC) [107] [reading] Five.
[108] Complete the following sentence.
[109] Something is the process of separating a liquid from [...] sediment by pouring. []
[110] Er
John (PS1UB) [111] So if you had a beaker full of sand with
Andrew (PS1UC) [112] Mm.
John (PS1UB) [113] water on it.
[114] You're just pouring the water off
Andrew (PS1UC) [115] Mm.
John (PS1UB) [116] carefully so that, you didn't
Andrew (PS1UC) [117] Oh.
John (PS1UB) [118] [...] any of the sand.
[119] Can
Andrew (PS1UC) [120] Oh.
John (PS1UB) [121] you remember what it's called?
Andrew (PS1UC) [122] No.
John (PS1UB) [123] It's a funny name.
[124] Decanting.
[125] Decantation.
Andrew (PS1UC) [126] Oh yeah.
John (PS1UB) [127] It's erm You don you don't come across it very
Andrew (PS1UC) [128] Yeah.
John (PS1UB) [129] much so I wouldn't bother about it too much.
Andrew (PS1UC) [130] [...] It's used to separate cream from milk. ...
John (PS1UB) [131] Again not too common.
[132] But this one, what what's the thing that's left on the
Andrew (PS1UC) [133] D or E ?
John (PS1UB) [134] C er C.
[135] What's the thing that's left on the filter paper?
Andrew (PS1UC) [136] [reading] A something is the solid left on the filter [] er eh ah.
John (PS1UB) [137] Which is the one that passes through the filter paper?
Andrew (PS1UC) [138] Er ... Oh what is it I've [...] .
[139] The [...] no, yeah?
John (PS1UB) [140] Mm.
[141] Maybe.
[142] They start they both start with er think of sort of fil.
Andrew (PS1UC) [143] I know it [...] .
John (PS1UB) [144] Fil. [...] .
Andrew (PS1UC) [145] Filtrates.
John (PS1UB) [146] It's what happens to half the answers.
Andrew (PS1UC) [147] Erm [...]
John (PS1UB) [148] Right so, what's left over?
Andrew (PS1UC) [149] The residue.
John (PS1UB) [150] Okay.
Andrew (PS1UC) [151] And we're left with this filtrate
John (PS1UB) [152] The filtrate is what goes through.
[153] There's an oil called filtrate, have you seen it?
[154] It's
Andrew (PS1UC) [155] No.
John (PS1UB) [156] quite an old fashioned erm been going for years.
[157] They've been going for years, they've been making motor oils, engine oil, it's called filtrate so that's the liquid.
[158] That maybe a way of remembering it.
[159] Erm Yeah that's those are the important ones, the residue and the filtrate and erm ... [...] problem with that then?
Andrew (PS1UC) [160] Mm.
John (PS1UB) [161] Radioactivity.
[162] What you what do you What are the important things about radioactivity?
Andrew (PS1UC) [163] Erm it can't [...]
John (PS1UB) [164] What is radioactivity?
Andrew (PS1UC) [165] Er ... erm [...]
John (PS1UB) [166] Okay, erm Can you give Do you know any anything which is radioactive?
Andrew (PS1UC) [167] Uranium, plutonium which is made out of uranium.
John (PS1UB) [168] Okay so they're reactive erm Is this a good thing this radioactivity?
Andrew (PS1UC) [169] No. [laugh]
John (PS1UB) [170] [laugh] Not if you're standing close to it . []
Andrew (PS1UC) [171] Definitely not!
John (PS1UB) [172] Okay er why not?
[173] What's it do to you?
Andrew (PS1UC) [174] Erm it's carcinogenic.
[175] Causes cancer.
[176] Erm
John (PS1UB) [177] Not a good idea.
[178] Erm have you heard of half life?
Andrew (PS1UC) [179] Yeah.
John (PS1UB) [180] What does that mean?
Andrew (PS1UC) [181] that, that's how long it takes for half ... of the radioactive isotopes to disappear.
John (PS1UB) [182] Great, yeah, that's a wonderful definition.
Andrew (PS1UC) [183] Eh.
John (PS1UB) [184] Okay so if start of with sort of kilogramme, a year later you've got half a kilogramme
Andrew (PS1UC) [185] Its half life is a year.
John (PS1UB) [186] then after another year from when you had half a kilogramme, a year later how much would you have?
Andrew (PS1UC) [187] Er quarter of a kilogramme.
John (PS1UB) [188] yeah.
[189] [...] each each year it sort of goes down to half.
[190] Okay.
[191] Erm radioactivity is You have to sort of get into what's happening inside the nucleus to understand it.
[192] What sort of particles have we got inside the nucleus.
Andrew (PS1UC) [193] Erm ... Inside the nucleus.
[194] Neutrons, mm .
John (PS1UB) [195] Okay neutrons.
Andrew (PS1UC) [196] Er protons.
John (PS1UB) [197] And protons.
Andrew (PS1UC) [198] Yeah.
John (PS1UB) [199] Neuto neutrons and protons .
Andrew (PS1UC) [200] And protons.
John (PS1UB) [201] And ... you get I mean it might be an idea if you could sort of handle this formula but it's not important really.
[202] ... A neutron ... it's a ... a piece of uranium.
[203] It's the ... It
Andrew (PS1UC) [204] Yeah.
John (PS1UB) [205] has to hit the uranium nucleus, and breaks it up into two ... other particles and it releases three neutrons.
[206] So if you think of the nucleus of uranium, lots of protons and lots of neutrons all bunched up together.
[207] Er snooker ball if you like, whacks into them, a neutron hits them [cough] and scatter them, and it forms into two big clumps, the new elements, two new elements and three odd snooker balls come flying out.
[208] Okay?
Andrew (PS1UC) [209] Mm.
John (PS1UB) [210] Now why is it important that we get When we sort of fire neutron in we get at least one neutron coming out?
Andrew (PS1UC) [211] Erm ... otherwise it would be a different ... element.
John (PS1UB) [212] Mm.
Andrew (PS1UC) [213] if it ha Say you fired one in and one didn't come out it would have one extra
John (PS1UB) [214] Well well yeah, it is a different element because I mean the neutrons ... don't effect the chemical properties very much.
[215] Uranium U two three five U two three eight, the only difference is o ones got a few more neutrons than the other.
[216] But what happens here is that the nucleus itself breaks into two big lumps with a different number of protons in now, so you've got two new elements.
[217] So they don't use up all the prot all the neutrons that the uranium had.
[218] three of them come out, now what happens if there are Right you fire this snooker ball into one uranium nucleus, it splits off and then three snooker balls come flying out and there's more uranium about what's gonna happen?
Andrew (PS1UC) [219] There's gonna be a [...]
John (PS1UB) [220] So if they hit if one of those hits another nucleus,
Andrew (PS1UC) [221] Mm.
John (PS1UB) [222] that one will break up as well,
Andrew (PS1UC) [223] Will break up an
John (PS1UB) [224] and release another three neutrons which can then hit another nucleus.
Andrew (PS1UC) [225] So on and so on and so on.
John (PS1UB) [226] And what do you call this?
Andrew (PS1UC) [227] Er a chain reaction.
John (PS1UB) [228] Right okay so that's why it's important that we get I mean if we just got one neutron out then theoretically you could sustain a chain reaction, but in practice it would be absorbed, it wouldn't they wouldn't all hit, some of them would miss, but as long as we can get on average about one, of those three, hitting another one, we can keep it going, and we get this chain reaction going and th the heat really builds up then, and that's what they use in a a nuclear reaction reactor.
[229] Okay.
[230] Do you know about the different types of radiation?
Andrew (PS1UC) [231] Erm
John (PS1UB) [232] alpha, beta, gamma radiation?
Andrew (PS1UC) [233] Er I think so, yeah.
[234] Sort of.
[235] S er I can't remember which is which.
John (PS1UB) [...]
Andrew (PS1UC) [236] One of them
John (PS1UB) [237] [...] names, what roughly what do they do?
Andrew (PS1UC) [238] Er some of them are at different se strength er
John (PS1UB) [239] Okay.
Andrew (PS1UC) [240] One can only be blocked by lead.
John (PS1UB) [241] Mhm.
Andrew (PS1UC) [242] Er we haven't really done much on it to
John (PS1UB) [243] No,
Andrew (PS1UC) [244] be honest.
John (PS1UB) [245] okay.
[246] I mean some you can stop 'em with a s sheet of thick paper or others will go through very solid objects and as you say you need a good sheet of lead to stop it.
[247] Erm ... right.
[248] Gamma radiation.
[249] We've got alpha, beta, gamma and gamma radiation is the stuff that stuff Really takes some stopping.
[250] When they when these particles sort of go into your body, what do they do?
Andrew (PS1UC) [251] Er ... oh erm ... don't know.
John (PS1UB) [252] Okay, okay.
[252_1] Erm well a lot of them are charged part I mean if you think of let's say the neutron, it smashes into a uranium atom which is a big, really massive nucleus, and splits it up.
[253] So if these neutrons come smashing into your body, they could break up any of chemicals that are very important for your life, for your body chemistry.
[254] One of the things they do tend to do is upset cells, upset the way cells replicate, which is why they start doing weird things and go off and get cancerous.
[255] Erm ... very common question is one the the different types of radiation, alpha, beta and gamma.
[256] And this this comes up, so often.
[257] Explain what is meant by the term Half life.
[258] Right, three marks and then they say [reading] The half life of iodine one three one is eight days.If you have a total mass Initial mass of one gramme, how much would you have left after eight days? []
[259] Okay?
[260] So you could do that one, no problem.
[261] [reading] One naturally occurring radioactive metal which is used in nuclear power stations. []
Andrew (PS1UC) [262] erm, I said it before erm er er
John (PS1UB) [...]
Andrew (PS1UC) [263] Uranium.
John (PS1UB) [264] Right, watch out for that one.
[265] That you don't say plutonium because that's not a naturally occurring
Andrew (PS1UC) [266] Plutonium, yeah.
[267] I'm pretty sure about that.
John (PS1UB) [268] Yeah that one's but I mean th if they say Name one radioactive metal, in nuclear power stations, then okay you can say radium er uranium or plutonium, but if they want a naturally occurring one then you're not gonna get any marks for saying plutonium.
[269] And then name one radioactive metal which is made in a power station?
[270] Okay.
[271] [reading] Most of our electricity is obtained from nuclear power stations or by b or by burning fuels.
[272] Two other sources of energy. []
[273] Which can be used to
Andrew (PS1UC) [274] Water, wind er ... [door opening]
Unknown speaker (FMRPSUNK) [275] You alright?
Unknown speaker (FMRPSUNK) [276] Yeah.
Unknown speaker (FMRPSUNK) [277] It's black with no sugar isn't it?
Unknown speaker (FMRPSUNK) [278] That's lovely.
John (PS1UB) [279] Thanks very much.
[280] [...] Coke.
[281] Yeah I mean I think you're pretty good on those, you know about alternative sources of energy and you've got a pretty good idea of nuclear power, what it's about erm you know half life ... erm Then this gets onto the technical bit.
[282] ... [reading] Control rods in a nuclear reactor, often contain boron.
[283] Give the electronic structure of a boron atom, one mark. []
[284] Well perhaps you wouldn't bother with that.
[285] Erm What do the control rods do?
Andrew (PS1UC) [286] Er ... There's a nuclear reaction which Inside the reactor, and that heats up water and the control rods is nuclear fuel, is it?
[287] Uranium, they've just put into the reactor, and it reacts with the other, I don't know what exactly how it works but, er
John (PS1UB) [288] What do the control rods sound as if they're doing?
Andrew (PS1UC) [289] They're controlling the reaction.
John (PS1UB) [290] Right what would happen if you didn't have any control rods, in your nuclear reactor?
[291] Someone just pulled the control rods out. ...
Andrew (PS1UC) [292] It wouldn't work.
John (PS1UB) [293] It would.
[294] [laugh] It would work very well [laugh]
Andrew (PS1UC) [295] Ah.
John (PS1UB) [296] It would run away, you'd get meltdown.
[297] See these these three neurons coming out every time one neutron goes in this chain reaction's getting bigger and bigger.
[298] Erm and all the uranium is fissioning, it's all splitting up, it's generating immense quantities of heat
Andrew (PS1UC) [299] Mm.
John (PS1UB) [300] and it'll explode, so the control rods are to absorb these extra neutrons.
[301] I mean if y if you put the control rods right in, it won't run at all.
Andrew (PS1UC) [302] No.
John (PS1UB) [303] Because any If okay the odd couple of neutrons did get through, they'd split up an atom, three more neutrons come out and they're immediately absorbed by the control rods.
[304] So when you run to get it started off, you have all your uranium fuel rods in the reactor and you're control rods and it's it's shut down at that stage okay, then you gradually start withdrawing the control rods, and see what's happening.
[305] If the temperature starts going [...] put 'em down a little bit more.
Andrew (PS1UC) [306] Yeah.
John (PS1UB) [307] And keep it so it's just ticking over, so that on average you're absorbing two of these neutrons, say and just one is going on to st start another one, and you just you know ju It's very fine control on the fuel rods.
Andrew (PS1UC) [308] Yeah.
John (PS1UB) [309] They usually run them at below peak efficiency, they run The Russian reactors they tend to run 'em at maximum efficiency which is you're very very close to the critical level where it could run away with a little mistake and whoops, you got Chernobyl.
[310] Okay, so that's what the control rods do, erm they're m also known as moderators, the
Andrew (PS1UC) [311] Mm.
John (PS1UB) [312] rods that go in there.
[313] Erm another question on there, isotopes, what's an isotope?
Andrew (PS1UC) [314] Erm ... is it, It's not an atom but it's You couldn't break say a piece of uranium or into an atom, but you could break it up into an isotope.
[315] An isotope is say several atoms put together
John (PS1UB) [316] No.
Andrew (PS1UC) [317] It's like a molecule is it?
John (PS1UB) [318] [...] like a molecule.
[319] Erm Think of two types of uranium, U two three five and U two three eight.
[320] They've got a different atomic weight, cos they've got a different number of neutrons, but they got the same number of protons and they've got the same pattern of electrons, and the pattern of those outer electrons is what decides its chemical properties.
[321] So if you did a few chemical test on U two three five, U two three eight, you wouldn't be able to tell the difference.
[322] [...] same thing.
[323] And they're called isotopes, of the same element.
[324] the only difference in the isotopes is one's got a few extra neutrons.
[325] So that's that's basically what an isotope is, it's a an element that has.
[326] Or isotopes of an element, they have the same chemical properties, they have the same outer structure and very much the same inner structure apart from one's got a few extra neutrons.
Andrew (PS1UC) [327] Right.
John (PS1UB) [328] So that's that's an isotope.
[329] There are other isotopes, not just uranium.
[330] have you heard of erm carbon fourteen, carbon twelve?
Andrew (PS1UC) [331] Yeah.
John (PS1UB) [332] Do they use it for dating?
Andrew (PS1UC) [333] yeah.
John (PS1UB) [334] Geological finds and things well, erm very often some of You'll find that some of the isotopes are radioactive and they break down into other things.
[335] So you need to know what an isotope is.
[336] Erm now the periodic table, we've looked at that before and it's the ... if you knew the periodic table and where everyone fitted in,every all the elements fitted in or you if you had a copy, you could very intelligent guesses.
Andrew (PS1UC) [337] yeah.
John (PS1UB) [338] Erm there's a new element here, you've never heard of it before let's say Carbon fif
Andrew (PS1UC) [339] Well we do get a copy of the periodic table in the exams.
John (PS1UB) [340] Yeah so They say what properties do you expect lithium to have, you'll have a look at it and you'll say well it's sort of going to be the same as sodium and potassium, rally.
[341] I mean you'll work out whether it's a bit more reactive or a bit less.
[342] And this is this is the bonding that we were thinking of as a couple of magnets or thinking of it as electrs electrostatic charge.
[343] C can really This one is magnesiums going round with two extra electrons there that it wants to get rid of
Andrew (PS1UC) [344] Yeah.
John (PS1UB) [345] And these two fluorines are both saying Oh I'd really This one's saying I'd love one extra electron to go in there, it just make up my set of eight, same
Andrew (PS1UC) [346] Yeah.
John (PS1UB) [347] for this one, so they, the three of them get together, the one M G and the two Fs.
[348] And then they can all be turn Then they're happy they This is sort of lent if you like, they say donated but think of it as lent, it's lent its electrons to the fluorines cos it wants to get rid of them and the fluorines wanted to take them so, it makes this nice bond.
[349] ... Right, here's one where they give you a little bit of the table ... This this is a That's a fairly complicated sort of thing that they give on the table, erm give you the valencies and the
Andrew (PS1UC) [...]
John (PS1UB) [350] A good guess.
[351] Still there's quite a bit.
[352] [reading] Oxidation and reduction. []
[353] What's Do you know what that is?
[354] Do you know what oxidation is?
Andrew (PS1UC) [355] Er ... [...]
John (PS1UB) [356] Right, so what what happens when a piece of paper burns, or sugar burns or
Andrew (PS1UC) [357] It's
John (PS1UB) [358] coal.
Andrew (PS1UC) [359] it's reacting and taking up oxygen.
John (PS1UB) [360] Okay, yeah, great.
[361] So that's that's the that's the big sort of main definition of oxidation, taking up oxygen.
[362] And the other on the other definition that we chemists use is if you take hydrogen from it.
[363] It's also oxidation.
[364] And then there's this other one where i where it loses electrons, that's sort of stretching it a bit.
[365] I mean it is it is genuinely part of the definition but the definition they had originally has got stretched and stretched so now it it doesn't there's no obvious tie up with oxidation, meaning burning and taking up oxygen, and reduction is the of opposite, so if you get the oxygen out or you put hydrogen in or where it gains electrons.
[366] Erm have you done anything on ... ionic lattices or giant metal lattices?
[367] You seen any erm X-ray crystallography pictures?
Andrew (PS1UC) [368] No.
John (PS1UB) [369] No.
[370] You can take X-ray pictures of these crystalline atoms, like salt and the all because, they all fit into a nice little pattern, you know when we were sort of playing about with them as though they've go t magnets on?
[371] Well they all make a a pattern sort of alternate sodium chlorine sodium chlorine [...] big block.
[372] ... This is all all chemistry, now can you remember those?
Andrew (PS1UC) [373] I always [...] And equations [...]
John (PS1UB) [374] It's not so much the equations
Andrew (PS1UC) [375] Yeah the models
John (PS1UB) [376] as the what that was all about.
[377] Tell me what you remember that was about?
Andrew (PS1UC) [378] Erm
John (PS1UB) [379] Not the actual chemicals but just ... the sort of question, that you'd get.
Andrew (PS1UC) [380] Er ... what is the molar mass of ... say you had s erm ...
John (PS1UB) [381] Oh.
Andrew (PS1UC) [382] Twenty grammes of a substance.
John (PS1UB) [383] Okay.
Andrew (PS1UC) [384] er
John (PS1UB) [385] Oh pick a pick an equation that you know, pretty well.
Andrew (PS1UC) [386] Mm an equation?
John (PS1UB) [387] Mm, like how do you make salt?
Andrew (PS1UC) [388] Er
John (PS1UB) [389] How do you make common salt?
Andrew (PS1UC) [390] Sodium and Chlorine.
John (PS1UB) [391] Mhm.
[392] But [...] we don't normally make it like that.
Andrew (PS1UC) [393] Yeah, I know.
[394] Er
John (PS1UB) [395] I did say we'd keep away from acid plus alkali gives
Andrew (PS1UC) [396] Yeah.
John (PS1UB) [397] Gives what?
Andrew (PS1UC) [398] Er water and a salt.
John (PS1UB) [399] Right, so which acid and which alkali would you use to make N A C L?
Andrew (PS1UC) [400] Er, chlorine yeah?
John (PS1UB) [401] Yeah so which which acid is that chlorine going to come from?
Andrew (PS1UC) [402] Er Sodium chloride, no that's salt.
[403] Er
John (PS1UB) [404] [...] that's what we're making, sodium
Andrew (PS1UC) [405] Yeah.
John (PS1UB) [406] chloride so we're gonna get that chloride from one of the the acids.
Andrew (PS1UC) [407] Yeah er Oh.
John (PS1UB) [408] Which acid has got a C L in its formula?
[409] [...] Don't worry about it.
Andrew (PS1UC) [410] N A C L.
[411] er nitric acid.
[412] No.
John (PS1UB) [...]
Andrew (PS1UC) [413] N A C Oh fucking hell!
John (PS1UB) [414] It's gotta it's almost got a chlorine sound in its name.
Andrew (PS1UC) [415] ... I can't think of it.
John (PS1UB) [416] We'll have we'll we'll have a very short tiny tiny little look at it even though it's almost a holiday, right.
[417] ... What have we got, we we want to we want to finish up with sodium chloride
Andrew (PS1UC) [418] N A C L
John (PS1UB) [419] N A and a C L.
Andrew (PS1UC) [420] Yeah.
John (PS1UB) [421] Right.
[422] So we've got to get this
Andrew (PS1UC) [423] It's hydrogen chloride [...]
John (PS1UB) [424] Right great okay, right ?
Andrew (PS1UC) [425] Oh I was thinking too hard.
John (PS1UB) [426] Yeah, okay so there's an H C L and we've got to get the N A from something, that's the acid ... and now we need an alkali.
[427] An alkali with sodium in it ... and the one's we usually use are the hydroxides.
Andrew (PS1UC) [428] [whispering] Yeah. []
John (PS1UB) [429] So what's sodium hydroxide.
Andrew (PS1UC) [430] Erm N A ... er it's got Hydrogen H, N A O H.
John (PS1UB) [431] That's it, good.
[432] N A O H.
[433] So there's the N A positive and the O H negative, so that's where we get our sodium chloride from and the H positive and the O H mix ... what does the H positive and the O H give us?
Andrew (PS1UC) [434] Erm, H two O.
John (PS1UB) [435] Right, [...] water.
[436] And we get H two O there.
[437] So they'd say erm write down the I mean if you're lucky they'll give perh perhaps on some questions they'll give it to you and on others they'll say write it down.
[438] Write down the formula, the equation for making sodium chloride, and then they'd say How many We want to make say two tonnes of sodium chloride, how many tonnes of hydrochloric acid is tat going to use up?
[439] Or maybe, the don't often but they can say How many tonnes of hydrochloric acid and how many tonnes of N A O H would we need to make that.
[440] And they're not [...] bothered about how much water you make.
[441] But that one As you saw from the the past papers that's a usually quite a bit of marks go in for that.
[442] And it's a doddle really isn't it?
Andrew (PS1UC) [443] Yeah.
John (PS1UB) [444] They give They'll tell you erm they'll give you a list of the weights for C L.
[445] N A, H all the rest of them.
[446] You just put them into the formula, ad them up and then you do your Well let's say ... fifty eight fifty eight tonnes of H C L gives say a hundred and twenty tonnes of N A C L.
[447] So how many tonnes would give one?
Andrew (PS1UC) [448] Er ... eight tonne will give one tonne of N A C L.
[449] Erm ...
John (PS1UB) [450] Fifty eight tonnes will give us a hundred and twenty tonnes.
Andrew (PS1UC) [451] Er I'm n How much do we Er how
John (PS1UB) [452] Let's say let's say we want to make
Andrew (PS1UC) [453] Can you repeat the question I didn't quite [...]
John (PS1UB) [454] Okay let's let's say fifty eight tonnes of H C L gives a hundred and twenty tonnes of N A C L.
Andrew (PS1UC) [455] Alright, how many
John (PS1UB) [456] And we want to make two hundred tonnes of N A C L.
Andrew (PS1UC) [457] Right, can I give [...]
John (PS1UB) [458] So, how much would you need?
Andrew (PS1UC) [459] To make a hundred and twenty, right [...]
John (PS1UB) [460] Yep [hand clap] .
Andrew (PS1UC) [461] You divide that by a hundred and twenty, divide [...] they cancel out so it's [...] so to make one tonne of N A C L you use fifty eight over a hundred and twenty then you just times that by [whispering] [...] [] erm [...] hundred and twenty times by two.
John (PS1UB) [462] Got it?
Andrew (PS1UC) [463] And that would be [...]
John (PS1UB) [464] Brilliant!
Andrew (PS1UC) [...]
John (PS1UB) [465] Yep, yep.
[466] and that's it, so that's that's the key to it.
[467] Well how much would I need to make one tonne?
[468] And then once you've got that it doesn't matter what it doesn't matter if they're asking to make fifty three point five or whatever.
[469] Once you've worked out how much you need to make one to Now that, that question is is a gift really isn't it?
Andrew (PS1UC) [470] Yeah.
John (PS1UB) [471] There's bound to be something of [...] , alright if I say there's bound to be perhaps this year there won't but [laugh]
Andrew (PS1UC) [472] Yeah.
John (PS1UB) [473] Going I it's on just about every year, cos it's an important part of the the chemistry.
[474] And it's not, you know, it's not really much chemistry in it, especially if they don't ask you f for this er equation but they just give it to you.
[475] And they give you all the other information you need.
[476] So that's that's one to Every now and again on your own just look through a couple of the papers and have a go at that, so that when it does come up on the exam you're not kicking yourself [laugh]
Andrew (PS1UC) [477] MM.
John (PS1UB) [478] and saying [wail] .
[479] I knew this, I was doing it I was getting the right answer!
Andrew (PS1UC) [480] [...] put the light on.
John (PS1UB) [481] Yeah, put the light on it's getting a bit
Andrew (PS1UC) [482] Dull
John (PS1UB) [483] as if it's gonna pour out there isn't it?
Andrew (PS1UC) [484] Yeah.
John (PS1UB) [485] [...] it really is.
[486] So, on that,wh not if but when that question comes up you should do very well on it I think.
Andrew (PS1UC) [487] Yeah.
John (PS1UB) [488] Yeah?
[489] And that was very quick as well, the way you worked it out, it's not gonna take you long to pile up with quite a few marks on that.
[490] And leave more for the others Have you done anything about gas volumes?
Andrew (PS1UC) [491] No, no.
John (PS1UB) [492] P one V one T one, doesn't mean anything to you?
[493] ... [...] ... That's an interesting one.
[494] Some of these [...] .
[495] Erm ... five point four, [reading] Which one of these [] just tell me about which one whether you think they're correctly
Andrew (PS1UC) [496] It's incorrectly
John (PS1UB) [497] whether they're correctly or incorrectly [...] go through it, each each bit at a time, show me how you're checking it.
Andrew (PS1UC) [498] [...] it's got two [...] on either side
John (PS1UB) [499] Yeah so that's good
Andrew (PS1UC) [500] so that's correctly balanced.
John (PS1UB) [501] ER what about the C Ls?
Andrew (PS1UC) [502] Oh yeah, it's got three C L two and that ones got
John (PS1UB) [503] So how many C Ls all together in three C L two?
Andrew (PS1UC) [504] Erm there's six.
John (PS1UB) [505] Yep, okay.
Andrew (PS1UC) [506] And in that one there's only three.
John (PS1UB) [507] Ah, are there?
Andrew (PS1UC) [508] Oh it's two [...]
John (PS1UB) [509] Right , think of think of it with the brackets on, two times the whole compound, and the
Andrew (PS1UC) [510] Yeah.
John (PS1UB) [511] compound has got two
Andrew (PS1UC) [512] Yeah.
John (PS1UB) [513] has got three C Ls in, so you've got your two times three again, so that one's okay.
Andrew (PS1UC) [514] Right.
John (PS1UB) [515] Right.
Andrew (PS1UC) [516] [reading] Two H two plus O two. []
[517] So there's two, there's four Hs on that side
John (PS1UB) [518] Right.
Andrew (PS1UC) [519] plus two Os.
[520] On this side, no that's not because it's only Yeah there is
John (PS1UB) [...]
Andrew (PS1UC) [521] two Os
John (PS1UB) [522] Right ,
Andrew (PS1UC) [523] there.
John (PS1UB) [524] think of the whole compound
Andrew (PS1UC) [...]
John (PS1UB) [525] as bracketed.
[526] Two lots of H two O.
[527] you could write it as gives H two O plus H two O.
Andrew (PS1UC) [528] Yeah.
John (PS1UB) [529] [...] been a bit long winded doing that.
Andrew (PS1UC) [530] Right, there's one Z on Z N on this side there's only one Z N on this side.
[531] This C U, there's only one here
John (PS1UB) [532] Mhm.
Andrew (PS1UC) [533] there's only one here.
[534] the S O four, yeah there's only one there and there's only one there so that's balanced .
John (PS1UB) [535] Okay, so that's okay.
Andrew (PS1UC) [536] F E two O three [whispering] and an F E two [] Yeah there's two F E
John (PS1UB) [537] Right F Es are okay, what about the Os?
Andrew (PS1UC) [538] The Os.
John (PS1UB) [539] How many Os all together on this side?
Andrew (PS1UC) [540] There's four Os here
John (PS1UB) [541] How many?
Andrew (PS1UC) [542] Four, one two three
John (PS1UB) [543] there's three from there, and how many from this one?
Andrew (PS1UC) [544] One, two.
John (PS1UB) [545] Right.
Andrew (PS1UC) [546] There's five.
John (PS1UB) [547] Think think of think of the brackets, right .
Andrew (PS1UC) [548] There's five, yeah.
John (PS1UB) [549] So it's sort of two
Andrew (PS1UC) [550] And there's six here.
John (PS1UB) [551] Right, so we've got five there, three add two.
[552] And on that side we've got six, so that one's not balanced.
[553] Erm and what about Is it balanced as far as the Cs go?
Andrew (PS1UC) [554] Er
John (PS1UB) [555] [...] we don't really need to go any further because we've found it's not balanced but we just for completeness, how many Cs on this side?
Andrew (PS1UC) [556] Er there's ... two.
John (PS1UB) [557] Yeah, two Cs from the two C Os, and how many Cs on that side?
Andrew (PS1UC) [558] Three.
John (PS1UB) [559] Three from the three [...] , so the Cs aren't balanced either.
Andrew (PS1UC) [560] Right.
John (PS1UB) [561] What about this last one?
Andrew (PS1UC) [562] There's one C U on that side,
John (PS1UB) [563] Mhm.
Andrew (PS1UC) [564] and on the other side, there's one C U.
John (PS1UB) [565] Yes so that's okay.
Andrew (PS1UC) [566] The S O four, there's one S O four on that side, and on the other side there's one S O four.
John (PS1UB) [567] Right, that's good.
Andrew (PS1UC) [568] Yeah.
[569] There's two N A on this side and there's two N A on
John (PS1UB) [570] Mhm.
Andrew (PS1UC) [571] that side.
[572] There's one two a O H on that side
John (PS1UB) [573] Good, two O Hs cos it's bracketed around the whole lot.
Andrew (PS1UC) [574] and then there's two O Hs there.
John (PS1UB) [575] Right so that's okay, so it was just that one that wasn't.
[576] That's that's the sort of erm quick question that they give that if you know what you're doing, again it's easy marks.
[577] So it's getting use to the notation, the number that goes in front of the compound applies to everything in the compound.
[578] So if we had two N A two S O four, that would be two times N A two you've got four N As and two times the S O four.
[579] Okay that was good.
[580] ... I didn't think I mean there's any Easy one here, plot the graph.
Andrew (PS1UC) [581] Yeah.
John (PS1UB) [582] Yeah.
Andrew (PS1UC) [583] Hate those questions because they take so much time.
Unknown speaker (FMRPSUNK) [...]
Unknown speaker (FMRPSUNK) [584] Really
Andrew (PS1UC) [585] I find.
[586] I I feel as though I'm not doing anything useful.
John (PS1UB) [587] You think though, this is a doddle, this is [...]
Andrew (PS1UC) [588] Mm.
John (PS1UB) [589] Poom!
[590] Plot it away and draw the graph, but it's you know
Andrew (PS1UC) [591] Mm.
John (PS1UB) [592] W would have we got for this one, say?
[593] See
Andrew (PS1UC) [594] Mm.
John (PS1UB) [595] Quite a few marks.
Andrew (PS1UC) [596] Oh yeah I'd do it, I'm just saying I'm
John (PS1UB) [597] So eight marks on it.
[598] Erm ... again practice would help.
[599] Before you draw it, look for what they're going to ask you.
[600] Because you might start from nought or something I mean they don't often do this but you might start from nought, and then they ask you What is it at minus ten?
[601] And you've started at nought here and you can't work out
Unknown speaker (FMRPSUNK) [602] Hi .
John (PS1UB) [603] where your [...]
Unknown speaker (FMRPSUNK) [604] Hi.
[605] Everything okay?
Andrew (PS1UC) [606] Yeah.
John (PS1UB) [607] Yes fine thanks.
Unknown speaker (FMRPSUNK) [608] [...] Do you want to have a drink or have you had one?
John (PS1UB) [609] I've got one thanks.
[610] Been
Unknown speaker (FMRPSUNK) [...]
John (PS1UB) [611] looked after.
Unknown speaker (FMRPSUNK) [612] Did anybody ring at all Andy?
Andrew (PS1UC) [613] No.
Unknown speaker (FMRPSUNK) [614] Okay, well I won't disturb you in the study.
John (PS1UB) [615] Okay.
[616] [...] So, before you decide on your end points on the graph, just check where they're asking [...] read the volume at twenty degrees C, that's okay.
[617] So if you do your nought to hundred, and draw your graph and just read off, what it gets on twenty.
[618] So again, erm a way of picking up a few marks, quite a few.
Andrew (PS1UC) [619] Yeah.
John (PS1UB) [620] Eight marks there, for something that's not really chemistry.
[621] Draw a graph.
Andrew (PS1UC) [622] Mm.
John (PS1UB) [623] If you can draw a graph you can you can get that.
[624] And all these are going to sort of pile up so that your The chemistry that you do know is going to you know
Andrew (PS1UC) [625] Yeah.
John (PS1UB) [626] Throw that in as well, and you'll have a pass.
[627] Have you done much on electrolysis?
Andrew (PS1UC) [628] Er ... a little bit, yeah.
John (PS1UB) [629] Mhm.
[630] Copper plating things and silver plating them
Andrew (PS1UC) [631] Er how they make aluminium.
John (PS1UB) [632] Okay
Andrew (PS1UC) [633] Mm.
John (PS1UB) [634] how they make aluminium.
[635] Erm where do they make aluminium?
Andrew (PS1UC) [636] Er
John (PS1UB) [637] Who makes the kitchen fol, that you've probably got in your kitchen.
Andrew (PS1UC) [638] [laugh] Don't know, I've never looked.
[639] Made in France [...]
John (PS1UB) [640] Probably Al Probably Alcan.
Andrew (PS1UC) [641] Yeah.
John (PS1UB) [642] Aluminium Canada.
[643] Cos they've so much hydroelectric Though they've got the er but they've erm They're used to [...] Lots of hydroelectricity, you need lots and lots of electricity, and it's very expensive, so there they've got big hydroelectric schemes and they make it. [break in recording]
John (PS1UB) [644] And what'll happen when you pass ... when you pass a current through hydrochloric acid?
[645] Well what's hydrochloric acid?
[646] What's the formula for it?
[647] ... H plus and C L negative, so what gasses would you think would come off when you pass electricity ... through it .
Andrew (PS1UC) [648] Erm Carbon dioxide.
John (PS1UB) [...]
Andrew (PS1UC) [649] Wh wh what was it again ?
John (PS1UB) [...]
Andrew (PS1UC) [650] I I heard you wrong, what did you say ?
John (PS1UB) [651] We got we got hydrochloric acid.
Andrew (PS1UC) [652] Yeah.
John (PS1UB) [653] Right. ...
Andrew (PS1UC) [654] Yeah.
John (PS1UB) [655] That's hydrochloric acid.
Andrew (PS1UC) [656] Yeah.
John (PS1UB) [657] But you think of it as ... if we move away slightly from the magnets
Andrew (PS1UC) [658] Oh it'll be
John (PS1UB) [659] in that they're electrically they really are electrical charges, and somebody comes up with a big positive electrical pole of a a battery
Andrew (PS1UC) [660] You're getting off hydrogen.
John (PS1UB) [661] Okay, so you get hydrogen
Andrew (PS1UC) [662] Sorry I don't know what came over me.
John (PS1UB) [663] Right, you'll get off hydrogen there and
Andrew (PS1UC) [664] Chlorine.
John (PS1UB) [665] And chlorine, alright.
[666] Erm Yeah they used to have a lot of trouble in submarines and things as they had problems with their batteries flooding and then they start to electrolyzing the [...] sodium chloride, the salt [...] the sea water, and getting chlorine given off.
[667] [laugh] It's not nice thing [...] .
[668] ... Leave that.
[669] ... This is a similar sort of thing to passing current through, but this time we're using it as a battery.
Andrew (PS1UC) [670] Yeah
John (PS1UB) [671] So the Z N, something that'll conduct, in dilute sulphuric acid, almost any dilute will, pure water won't conduct.
[672] Everyone says Well water, you know, really conducts electricity
Andrew (PS1UC) [673] Mm.
John (PS1UB) [674] if it's absolutely pure
Andrew (PS1UC) [675] It won't
John (PS1UB) [676] It's not a brilliant conductor at all, but l there's always a little bit of impure, a
Andrew (PS1UC) [...]
John (PS1UB) [677] little bit acid, say from
Andrew (PS1UC) [678] Mm.
John (PS1UB) [679] carbon dioxide in the air, enough to make it conduct.
[680] And it splits up, so your your Z N double positive comes out of the zinc rod.
[681] Double positives are taken away making it negative and your H positives go in here, making it positive, so you get a you get a little a little potential difference, a little difference in voltage, which gives a Any any two metals if you put them together and make them a bit damp, or even if you don't make them damp, you usually get a little a tiny voltage.
[682] So if we pick metals that have got a big difference in their electrical potentials, we're gonna get a useful battery.
[683] The er this is This sort of cell, you can call it a cell rather than a battery, makes electricity.
[684] Now a normal car battery called an accumulator, accumulator or battery rather than a cell, doesn't actually make it, it stores it.
Andrew (PS1UC) [685] Right.
John (PS1UB) [686] Right, so you make it with your dynamo or your alternator
Andrew (PS1UC) [687] Yeah.
John (PS1UB) [688] and you sort of fill up the battery, and then you can draw it off, but the battery itself isn't making electricity it's just storing [...] cells, like the little cells in that, the cells you get in your normal little batteries, and when they've finished making it you chuck 'em away.
[689] They get to the stage where they've clogged themselves up with the the by-products, so part of making a battery is trying to design it so it doesn't clog itself up.
[690] So you don't finish up with a battery that as soon as you've used it for about a minute, that's it can't get any more
Andrew (PS1UC) [691] Mm.
John (PS1UB) [692] voltage out of it.
[693] Erm ... yeah How how is running water used for making electricity?
Andrew (PS1UC) [694] Running water?
John (PS1UB) [695] You said earlier running water might be one of the ways of the alternative methods of making electricity.
Andrew (PS1UC) [696] Erm you could use tidal or wave power but say
John (PS1UB) [...]
Andrew (PS1UC) [697] it's coming downhill when it rains, the
John (PS1UB) [698] Mm.
Andrew (PS1UC) [699] clouds go up a mountain it rains
John (PS1UB) [700] Yeah.
Andrew (PS1UC) [701] it gets to the top.
[702] Rain coming down, usually come down in a stream so you have some kind of erm mill
John (PS1UB) [703] What an ord
Andrew (PS1UC) [704] water mill .
John (PS1UB) [705] Right.
Andrew (PS1UC) [706] And that turns your dynamo generator whatever you want, [...]
John (PS1UB) [707] Okay, right, [...] the old water mill used to turn the stones in the wil mill really you could turn a generator.
[708] Erm what do they normally have at the big hydroelectric works?
Andrew (PS1UC) [709] Erm
John (PS1UB) [710] Is it just a little stream running along or what?
Andrew (PS1UC) [711] No it's usually a water wall.
John (PS1UB) [712] Yeah, quite a high one so they have a big dam to give [...] a good head water, a good height of water, and that water comes ... Drops down through quite a quite a height, and then they have a turbine sort of force it into a turbine with a turbine and it really spins that turbine th that's joined top the alternator and makes the electricity.
[713] Okay?
[714] What's a catalyst?
Andrew (PS1UC) [715] Er it speeds up a reaction, it isn't used in the reaction, it just speeds it up.
John (PS1UB) [716] What do you mean by It isn't used in the reaction?
Andrew (PS1UC) [717] Erm it doesn't it's not necessarily needed for the reaction, it the reaction will still happen without it.
John (PS1UB) [718] The reaction could happen slowly without it generally
Andrew (PS1UC) [719] Yeah.
John (PS1UB) [720] but it's a it makes the reaction a whole lot faster .
Andrew (PS1UC) [721] It's not used in great quantities in the reaction.
John (PS1UB) [722] Right it's usually only a small quantity needed, because although it is it's used it's continually sort of restored.
[723] So it's
Andrew (PS1UC) [724] Yeah.
John (PS1UB) [725] Erm I mean some people say, quite wrongly, that it's something that doesn't take any part in the reaction but speeds it up, but how can it do that.
[726] It does take a part in the reaction but it keeps getting returned back to its original state.
Andrew (PS1UC) [727] Yeah.
John (PS1UB) [728] Can you think of any catalysts?
Andrew (PS1UC) [729] Er is it potassium permanganate?
John (PS1UB) [...]
Andrew (PS1UC) [730] What
John (PS1UB) [731] Pla ... a duck billed
Andrew (PS1UC) [732] Pardon?
John (PS1UB) [733] A duck billed
Andrew (PS1UC) [734] Platypus.
John (PS1UB) [735] And it's not platypus it's ... sounds like a type of pen.
Andrew (PS1UC) [736] Platinum.
John (PS1UB) [737] Right, platinum.
[738] Platinum is quite a common one in industrial processors,the other things are used
Andrew (PS1UC) [...] [tape change]
Andrew (PS1UC) [739] Right, er Right, it's how long it takes for a whole substance to react, so it can't Say you put two ...
John (PS1UB) [740] Put it in your own words.
Andrew (PS1UC) [741] Say you put two chemicals together.
John (PS1UB) [742] Right, okay.
Andrew (PS1UC) [743] It's how long it takes for those to react together until they've stopped reacting.
John (PS1UB) [744] Right, okay so if we put this one If we put hydrochloric acid and caustic soda together, they'd start reacting and after a while it would all be finished.
Andrew (PS1UC) [745] Yeah.
John (PS1UB) [746] Yeah.
[747] This p this type of reaction goes pretty quickly.
[748] Erm what do you think affects the rate at which the reaction goes?
Andrew (PS1UC) [749] Er ... [whispering] What do you think affects the [...] reaction [...] [] Er the amounts of
John (PS1UB) [750] Okay.
[751] It's the concentrations
Andrew (PS1UC) [...]
John (PS1UB) [752] of the reactants.
Andrew (PS1UC) [753] Heat.
John (PS1UB) [754] And heat is the big thing.
[755] How does heat affect the rate at which the reaction goes?
Andrew (PS1UC) [756] Usually the hotter it is, the faster the reaction.
John (PS1UB) [757] Right, [cough] well nothing's happened here, let's just stick a bunsen under it, warm it up a bit, get it moving.
Andrew (PS1UC) [758] Mm.
John (PS1UB) [759] Yeah, so ... that's a graph there and this is the sort of graph that you're sometimes ask asked to draw to ... get it going, okay?
Andrew (PS1UC) [760] Yeah.
John (PS1UB) [761] [...] really black isn't it ?
Andrew (PS1UC) [762] Gonna chuck it down any minute [...]
John (PS1UB) [763] It is, it is.
Andrew (PS1UC) [764] Well it doesn't go dark till twenty to eight.
John (PS1UB) [765] I know, it's going to go It's gonna be a good [...] out there.
[766] What's a reversible reaction?
Andrew (PS1UC) [767] Erm it's a reaction, say you put two chemicals together.
John (PS1UB) [768] Mm.
Andrew (PS1UC) [769] they're not stuck together you can separate them again, it's The reaction can go both ways.
John (PS1UB) [770] Right the reaction goes both ways.
[771] A lot of chemical reactions are actually reversible, but the tend to be mainly going very much in one direction, so we just say we just write it as though it only went in one direction.
[772] And what things could affect which direction it goes in?
Andrew (PS1UC) [773] Er ... heat again,
John (PS1UB) [774] Yeah.
Andrew (PS1UC) [775] er oxygen available to them
John (PS1UB) [776] Yeah, if it's
Andrew (PS1UC) [777] Er
John (PS1UB) [778] one that uses oxygen, that would affect it.
Andrew (PS1UC) [779] Erm What state
John (PS1UB) [780] And
Andrew (PS1UC) [781] they were in to start with.
[782] Whether they were together to start with or whether they were separate.
John (PS1UB) [783] Okay and the other thing that you said for the the first question to what affects what affects he rate of reaction normally in a normal reaction.?
Andrew (PS1UC) [784] Er
John (PS1UB) [785] What's the other thing [...]
Andrew (PS1UC) [786] Quantity.
John (PS1UB) [787] So the concentrations can affect it.
[788] As ... Let's say you've got a reaction which is producing erm oxygen.
[789] As they oxygen concentration that's being produced, gets very high it slows it down, it slows it and it stops.
[790] Now if we can take away tat excess oxygen that's being produced, it'll start going again.
[791] If we put more oxygen in, it might start going back the other way.
[792] So by controlling the concentration of the reagents that will affect which way it goes and a lot of them are temperature sensitive, we heat it up it goes one way, cool it down it goes the other.
[793] So this On on these general points like this you could pick up quite a few marks, but a lot of the questions are not that technical erm and they're stuff that you do know.
[794] Erm like the answers you're giving now, these are all
Andrew (PS1UC) [795] Yeah.
John (PS1UB) [796] good for picking up the marks.
[797] Now, I think you know quite about the atmosphere, don't you?
Andrew (PS1UC) [798] Yeah.
John (PS1UB) [799] Erm ... what causes the What's the greenhouse effect and what causes it?
Andrew (PS1UC) [800] It's the build up of carbon dioxide [...] er in the atmosphere.
John (PS1UB) [801] Right why is it called a
Andrew (PS1UC) [802] And
John (PS1UB) [803] greenhouse effect?
Andrew (PS1UC) [804] The light comes in from the sun, heat.
John (PS1UB) [805] Right, yeah.
Andrew (PS1UC) [806] And it ... here's the rain.
[807] And it bounces it comes in through the atmosphere, through all the gasses, they can't leave again, as it usually can.
[808] Well part of it can leave again, but as it is more is getting trapped inside so it's getting hotter
John (PS1UB) [809] Good.
Andrew (PS1UC) [810] and the heat can't leave.
John (PS1UB) [811] Right so more more heat stays in than escapes back out of it.
[812] It's blocking, it's acting like a a bit of a duvet if you like.
Andrew (PS1UC) [813] Mm.
John (PS1UB) [814] Erm in the same way as th the glass in a greenhouse works, that it let's the radiant heat in but then it doesn't let so much out, so the heat builds up.
[815] And what's the effect of this?
[816] Of the
Andrew (PS1UC) [817] Erm
John (PS1UB) [818] Isn't this a good idea because we'll all be nice and warm now?
Andrew (PS1UC) [819] No because the polar ice caps will melt, sea levels
John (PS1UB) [820] Okay.
Andrew (PS1UC) [821] will rise.
[822] Erm the hot places already, like deserts and mid Africa, places on the equator will
John (PS1UB) [...]
Andrew (PS1UC) [823] get too hot, things will die.
John (PS1UB) [824] Right.
Andrew (PS1UC) [825] Etcetera etcetera.
John (PS1UB) [826] And because the sea levels rise a lot of places could get flooded
Andrew (PS1UC) [827] Mm.
[828] Basically
John (PS1UB) [829] So
Andrew (PS1UC) [830] [...] less place to live
John (PS1UB) [831] Right.
Andrew (PS1UC) [832] because anywhere that is, it'll be too hot in places so people go to cooler places and cool places [...] will be getting covered in water.
John (PS1UB) [833] Good, okay, yeah, great.
[834] Erm also there could be th will cause other climatic changes so that people who don't normally get rain will get gallons and gallons of it.
[835] People who you think [...] It's all melting, there'll be more wet about but there could well be more deserts and [...] So there's quite a lot going on there.
[836] What sort of pollutants do cars produce?
Andrew (PS1UC) [837] [sigh] Lot's er carbon dioxide, er is one.
John (PS1UB) [838] Right.
Andrew (PS1UC) [839] There's when the used leaded petrol, lead.
John (PS1UB) [840] Right.
Andrew (PS1UC) [841] And so on, er
John (PS1UB) [842] Yeah.
[843] What hap
Andrew (PS1UC) [844] Carbon monoxide.
John (PS1UB) [845] Good, carbon monoxide,s when when carbon is burnt from any of the fuels, petrol and sort of the hydrocarbons, burn them very efficiently and very completely you get carbon dioxide which isn't I mean it's not brilliant but it's not toxic.
[846] Carbon monoxide is lethal.
Andrew (PS1UC) [847] I actually, I got a car magazine today er [...] and Saab have actually built a car, and you know they've got catalytic converters now?
John (PS1UB) [848] Yeah.
Andrew (PS1UC) [849] It drives around and the air that comes out of its exhaust is actually cleaner than when it comes in .
John (PS1UB) [850] Is [laugh] [...] Great! []
Andrew (PS1UC) [851] It's actually it's brilliant and they [...]
John (PS1UB) [cough]
Andrew (PS1UC) [852] put it into production.
[853] Because
John (PS1UB) [854] So, they reckon
Andrew (PS1UC) [855] if you clean the air as you go
John (PS1UB) [856] Yeah
Andrew (PS1UC) [857] I mean it's
John (PS1UB) [858] They reckon if everyone drove round this [...] it up.
[859] So that's what what what else is it doing, this this new car, then, what else is it cleaning up?
[860] What
Andrew (PS1UC) [861] Er
John (PS1UB) [862] what about these other things that are in the air, does it clean clean them up as well?
Andrew (PS1UC) [863] Erm
John (PS1UB) [864] I mean th it's Presumably it must be putting out unburned hydrocarbons.
Andrew (PS1UC) [865] Yeah.
John (PS1UB) [866] When you've got an engine, erm, you Let's say we've got an engine with a fixed amount of petrol going in all the time.
[867] Now you've got to balance the air supply
Andrew (PS1UC) [868] Yeah.
John (PS1UB) [869] so that
Andrew (PS1UC) [870] It burns the maximum [...]
John (PS1UB) [871] Just as just all that oxygen is used up just to burn it, erm But if you don't give it enough air what will happen?
Andrew (PS1UC) [872] Erm it'll die.
[873] it'll it won't fire properly.
John (PS1UB) [874] Mm okay so let's
Andrew (PS1UC) [...]
John (PS1UB) [875] say we've got it just running on a very weak mixture, erm
Andrew (PS1UC) [876] Erm
John (PS1UB) [877] and there's not much there's not much fuel at all, but there is a lot of air going in, would you expect it all to be burned?
Andrew (PS1UC) [...]
John (PS1UB) [878] Mm, we c could get [...] most of a
Andrew (PS1UC) [879] No [...]
John (PS1UB) [880] lean burn we could get close
Andrew (PS1UC) [881] Yeah.
John (PS1UB) [882] to most of it and we wouldn't be producing too much unburnt fuel coming out of the back, you know
Andrew (PS1UC) [883] Mm.
John (PS1UB) [884] when you start a car on choke, pooh you can smell
Andrew (PS1UC) [885] Yeah.
John (PS1UB) [886] the petrol being pumped out of the back, that
Andrew (PS1UC) [887] Yeah.
John (PS1UB) [888] hasn't been burnt.
[889] Okay, and you'd be getting carbon monoxide out cos you're not ... erm okay, various things like that.
[890] Now
Andrew (PS1UC) [891] Yeah.
John (PS1UB) [892] what's That that's As you say it'll The engine's not gonna have any power
Andrew (PS1UC) [893] No.
John (PS1UB) [894] when there's hardly any petrol, and it's very.
[895] So if you stick your foot down hard on the accelerator, you squirt [laugh] a load of petrol in
Andrew (PS1UC) [896] Yeah.
John (PS1UB) [897] and the air can't cope with that, can't burn it all up, so what happens then?
[898] When you've
Andrew (PS1UC) [899] Erm
John (PS1UB) [900] got a rich mixture. ...
Andrew (PS1UC) [901] It'll The When there's not enough air and there's too much petrol
John (PS1UB) [902] Yeah.
Andrew (PS1UC) [903] Erm only part of it will burn and it'll go out through the exhaust, the
John (PS1UB) [904] Okay.
Andrew (PS1UC) [905] rest of the petrol.
John (PS1UB) [906] So you've got unburnt fuel going out erm
Andrew (PS1UC) [907] Much more flammable though.
John (PS1UB) [908] And what what else have we got going out?
[909] Cos we hadn't got enough enough air to burn all the carbon in these hydrocarbons.
Andrew (PS1UC) [910] So there'll be carbon, carbon monoxide.
John (PS1UB) [911] There'll be carbon monoxide coming out and there might even, as you say, be carbon, with lumps of soot.
Andrew (PS1UC) [912] Yeah.
John (PS1UB) [913] Erm as well as that we get a little bit of sulphur dioxide and we get ... oxides of nitrogen, which are pretty nasty, those are the one's they et around Los Angeles, and the big smoggy cities.
[914] Erm Nitric and nitrous oxide.
Andrew (PS1UC) [...]
John (PS1UB) [915] Erm and the oxide of nitrogen.
[916] You remember when we were talking about making sulphuric acid, remember how we made it?
Andrew (PS1UC) [917] Yeah.
John (PS1UB) [918] [...] how do we make it?
Andrew (PS1UC) [919] Er sulphur, hydrogen, oxygen er
John (PS1UB) [920] Okay so we burnt the sulphur, made sulphur dioxide
Andrew (PS1UC) [921] Yeah.
John (PS1UB) [922] Erm burned that again to get sulphur trioxide and then effectively
Andrew (PS1UC) [923] Mm.
John (PS1UB) [924] squirted water on it.
Andrew (PS1UC) [925] Mm.
John (PS1UB) [926] And so sulphur trioxide add water makes sul sulphuric acid .
Andrew (PS1UC) [927] Sulphuric acid.
John (PS1UB) [928] Well we've got sulphur dioxide coming out here ... and the water will make sulphurous acid, which is again pretty nasty and we've got oxides of nitrogen
Andrew (PS1UC) [...]
John (PS1UB) [929] coming out with the water, they make nitrous and nitric acids,
Andrew (PS1UC) [930] Yeah.
John (PS1UB) [931] so you can see why it's pretty nasty
Andrew (PS1UC) [932] Yeah.
John (PS1UB) [933] er if it's a city with lots of cars running
Andrew (PS1UC) [934] Yeah.
John (PS1UB) [935] Okay, what happens to metals?
Andrew (PS1UC) [936] Erm
John (PS1UB) [937] Why do why does iron rust, for example?
Andrew (PS1UC) [938] Er it reacts with water and air.
John (PS1UB) [939] Okay, good.
[940] With water and air, yeah that's the big point.
[941] Erm okay?
[942] Look at that one.
[943] Tin plating, why does that stop iron from rusting?
Andrew (PS1UC) [944] Erm tin doesn't rust and it protects it from the air and water, you get 'em [...]
John (PS1UB) [945] Stops the air and water getting to it so it can't rust, and then I mean this is pretty straight forward, if the tin surface is then scratched it will rust, why?
Andrew (PS1UC) [946] [...] because it can get into contact with the
John (PS1UB) [947] Right, and why doesn't this happen with zinc plating, galvanizing?
Andrew (PS1UC) [948] Erm it doesn't come off so easily, [...]
John (PS1UB) [949] Doesn't come off so easily and it sort goes into it a bit,
Andrew (PS1UC) [950] Yeah.
John (PS1UB) [951] a little bit down into the [...] .
[952] ... [reading] Suggest alternative materials because iron rust alterial alternative materials for a household bath, [] what could you make it of instead of iron?
Andrew (PS1UC) [953] Erm, [...] doesn't rust, steel.
[954] Possibly.
John (PS1UB) [955] [yawn] I'm sure that steel rusts.
Andrew (PS1UC) [956] Yeah, erm ...
John (PS1UB) [957] They do make 'em out of this
Andrew (PS1UC) [958] Yeah.
John (PS1UB) [959] alternative substance.
Andrew (PS1UC) [960] Aluminium?
[961] No [...]
John (PS1UB) [962] Be very it would be a very expensive cos it's an expensive
Andrew (PS1UC) [963] Yeah.
John (PS1UB) [964] thing aluminium.
[965] Be a g I mean it would be a nice bath, it would be light and very strong.
[966] Erm
Andrew (PS1UC) [967] Mm.
John (PS1UB) [968] What about a Coca-Cola can?
Andrew (PS1UC) [969] That's aluminium.
John (PS1UB) [970] Right aluminium, yeah.
Andrew (PS1UC) [971] Yeah, ... er [whispering] I'm trying think [...] [] steel or aluminium, plastic.
John (PS1UB) [972] Yep.
[973] Okay [...]
Andrew (PS1UC) [974] I was thinking
John (PS1UB) [975] this is the this is it's so easy, [...] you think what's an alternative to steel, oh it must be a metal, how could I make a bath out of copper or [...] what could it be.
Andrew (PS1UC) [976] Yeah, I was thinking
John (PS1UB) [977] And it's it's obvious once you've thought about it
Andrew (PS1UC) [978] Yeah.
John (PS1UB) [979] plastic an you know acrylic baths, things like that.
[980] Oh now we get on to the really difficult stuff.
[981] [reading] The most abundant gas in the air is? []
Andrew (PS1UC) [982] Nitrogen.
John (PS1UB) [983] Okay.
[984] [reading] Liquid air secarate separated into its components by []
Andrew (PS1UC) [985] Er
John (PS1UB) [986] How do they separate it?
Andrew (PS1UC) [987] Liquid air, freezing it, cooling it [...]
John (PS1UB) [988] Now, liquid air.
Andrew (PS1UC) [989] Oh.
John (PS1UB) [990] If the air is liquid, what temperature is it going to be at?
Andrew (PS1UC) [991] Er ... don't know, erm er
John (PS1UB) [992] What sort of temperature is liquid nitrogen at?
Andrew (PS1UC) [993] Low [laugh]
John (PS1UB) [994] Low.
[995] Liquid oxygen?
Andrew (PS1UC) [996] Er low.
John (PS1UB) [997] Low, right.
[998] So liquid air
Andrew (PS1UC) [999] Is separated.
John (PS1UB) [1000] is low [laugh] low temperature.
[1001] How do you separate it?
[1002] How do you separate the oxygen ad the nitrogen out of liquid air?
Andrew (PS1UC) [1003] Er, burn something in it.
[1004] [...] No
John (PS1UB) [1005] You could do okay you could do that and then you would have used up all the oxygen and you'd just have nitrogen left, but burning something in a liquid in liquid air is gonna be a bit awkward, it couldn't be done.
[1006] Erm ... what will happen if you let the liquid air warm up a little bit?
Andrew (PS1UC) [1007] Er one of them would melt.
John (PS1UB) [1008] Right one of them will ... not melt but?
Andrew (PS1UC) [1009] S er evaporate.
John (PS1UB) [1010] Right, boil off I's very low It's boiling but it is at low temperature when it's boiling.
[1011] You let the temperature come up until it reaches the boiling point
Andrew (PS1UC) [1012] Yeah.
John (PS1UB) [1013] of the first one to boil and boil all that off and then you're left with the other one.
[1014] So it's quite a s a simple process, the idea of it is a simple idea.
[1015] Erm ... [reading] The [] something or other [whispering] is the process by which green plants synthesize carbohydrates from carbon dioxide and water using sunlight as a source of energy and chlorophyll as a catalyst. []
Andrew (PS1UC) [1016] Something [reading] is the process by which gr [] Oh photosynthesis.
John (PS1UB) [1017] Good, yeah, great.
Andrew (PS1UC) [1018] [reading] A pollutant in the air which leads to the production of acid rain is [] Ooh Carbon dioxide isn't it?
[1019] NO.
John (PS1UB) [1020] Carbon dioxide does give a very slightly acidic
Andrew (PS1UC) [1021] Er ...
John (PS1UB) [1022] rain but it's that's not really
Andrew (PS1UC) [1023] It's sulphur dioxide.
John (PS1UB) [1024] Good Sulphur dioxide, yeah we get sulphurous acids and sulphuric acids .
Andrew (PS1UC) [1025] [reading] Incomplete combustion of diesel fuel produces a poisonous gas called? []
[1026] ... Diesel fuel?
John (PS1UB) [1027] Well that's a tricky one.
[1028] Erm think of it as petrol.
[1029] the incomplete combustion of petrol, produces a poisonous gas called ?
Andrew (PS1UC) [1030] called carbon monoxide.
John (PS1UB) [1031] Right, and it's the same for diesel.
Andrew (PS1UC) [1032] Right.
John (PS1UB) [1033] It's just that they've probably got so tired of putting petrol in each year
Andrew (PS1UC) [1034] Mm.
John (PS1UB) [1035] [...] we'll fool them we'll put we'll say diesel
Andrew (PS1UC) [1036] Diesel
John (PS1UB) [1037] this year.
[1038] Yeah, it's a hydrocarbon.
[1039] It's got lots, it's got hydrogen and it's got lots of carbons in and these carbons when they don't burn completely, when they only sort of partly burn, they form carbon monoxide instead of dioxide.
[1040] Okay ... Ooh.
[1041] Now you know, you're pretty well up on water supplies, where it comes from, what it does?
Andrew (PS1UC) [1042] Yeah.
John (PS1UB) [1043] Erm ... You [...] You know the formula Erm do you know the test for water?
Andrew (PS1UC) [1044] The test?
John (PS1UB) [1045] Mm.
[1046] No, you may not have come across it.
Andrew (PS1UC) [...]
John (PS1UB) [1047] You get white an
Andrew (PS1UC) [1048] Er
John (PS1UB) [1049] white anhydrous copper sulphate.
Andrew (PS1UC) [1050] Oh yeah, it turns blue.
[1051] I I knew that it turned blue but I didn't know that was the test.
John (PS1UB) [1052] Yeah.
[1053] It turns blue and that's that's a good test for water.
[1054] Erm essential for life, we're about two thirds water, it ll depends depending on which book you read how much of us is water, but erm Don't forget that it's an incredible solvent, water .
Andrew (PS1UC) [1055] Yeah.
John (PS1UB) [1056] Lot's and lot's of things will dissolve in water.
[1057] You tend to think oh so many things don't dissolve in water but think of the other ways round.
[1058] So many things
Andrew (PS1UC) [1059] Salt all the salts.
John (PS1UB) [1060] Mm.
[1061] I mean what do washing each day if you want to if you want to clean the walls, want to do
Andrew (PS1UC) [1062] Mhm.
John (PS1UB) [1063] bit of cloth [...] in water .
Andrew (PS1UC) [1064] All the soaps in your kitchen all the soaps in your bathroom.
[1065] They're all stuff which dissolves in water.
John (PS1UB) [1066] Yeah.
[1067] And if you get It's only when you get oily greasy stains that you think, oh I'd better some ethanol or
Andrew (PS1UC) [1068] Mm.
John (PS1UB) [1069] a bit of petrol or something to try and get this off.
[1070] So you pretty well up on water.
[1071] Water as a solvent, you know all about that.
[1072] Rain coming down, rain down to the sea, evaporating off again.
[1073] Erm ... now okay.
[1074] ... What will happen there, if you've got a shallow pool and a couple of deep pools and the sun is shining on it?
Andrew (PS1UC) [1075] That one will evaporate sooner.
John (PS1UB) [1076] Right.
[1077] I wonder about the wa What about the water temperature?
Andrew (PS1UC) [1078] Erm, it will be hotter.
John (PS1UB) [1079] Right, so a
Andrew (PS1UC) [1080] Er
John (PS1UB) [1081] little shallow pool down by the seaside will be warmer .
Andrew (PS1UC) [1082] Yeah, it'll be warmer near the top in these as well.
John (PS1UB) [1083] Mm.
[1084] Erm
Andrew (PS1UC) [1085] [tut] Er
John (PS1UB) [1086] M yeah it will be it will be warmer. [...]
Andrew (PS1UC) [1087] They Those would evaporate at the same rates, although that one would be gone sooner because there's less off it.
John (PS1UB) [1088] Yep.
[1089] All looks good.
[1090] ... Chlorine is a poisonous gas.
[1091] So why do they put it in household water?
Andrew (PS1UC) [1092] Er, it kills off It's
John (PS1UB) [1093] Yep [laugh] cos it's poisonous it kills off [] sort of virtually all life
Andrew (PS1UC) [1094] Yeah.
John (PS1UB) [1095] and what they hope is that most it has sort of been has disappeared by the time it gets to us
Andrew (PS1UC) [1096] Mm.
John (PS1UB) [1097] so it doesn't kill us off.
[1098] but you can still Sometimes you can smell it can't you?
[1099] Taste it in your water.
Andrew (PS1UC) [1100] Oh, yeah it's really bad in our water,
John (PS1UB) [1101] Yeah.
Andrew (PS1UC) [1102] it Sometimes it really
John (PS1UB) [1103] especially if
Andrew (PS1UC) [1104] stinks of bleach.
John (PS1UB) [1105] Yeah.
Andrew (PS1UC) [1106] With the fluoride and the chlorine.
John (PS1UB) [1107] If they've been changing the pipes or digging them up or something they often flush it through with a load of chlorine, [disgusted sound] [...] the water of or b Boil it erm As water get's hotter, and something like sugar, would you get would you find, Let's say you get a cup of cold water and you try and dissolve as much sugar as you can in it, and then you try hot water, try disolv
Andrew (PS1UC) [1108] Dissolve more in the hot water.
John (PS1UB) [1109] Okay.
[1110] What about gases.
[1111] Do they, would you get more gas dissolved in hot or in cold water?
Andrew (PS1UC) [1112] More in cold wouldn't you?
John (PS1UB) [1113] Yeah, as you as you heat up the water the gases boil out of it, so if wanted to get rid of the chlorine in your water, boiling it gets rid of quite a lot, it forces the chlorine t to boil out.
[1114] ... Ooh, skip that [...] [laugh]
Andrew (PS1UC) [1115] Acids bases and slats.
John (PS1UB) [1116] Erm I know you've probably had more than enough of that, but keep keep having a little look
Andrew (PS1UC) [1117] Yeah.
John (PS1UB) [1118] at those, because you've I mean you've done so much work on the, you're doing so well with them it would be a shame to just let it sort of slip out of your mind.
Andrew (PS1UC) [1119] yeah.
John (PS1UB) [1120] Erm you find that more and more constant repetition, each time you go back to it, there's less that you've forgotten, less that seems new and more that seems obvious and you'll be saying to yourself, sort of m You know of course Yeah I don't need to read this, tat's obvious that's obvious.
[1121] Whereas a few months ago it wasn't tat obvious.
[1122] Because nothing is obvious until you [laugh]
Andrew (PS1UC) [1123] Mm.
John (PS1UB) [1124] until you've learnt it.
[1125] Metals, can you think of any metals?
Andrew (PS1UC) [1126] Erm any metals that what?
[1127] Erm
John (PS1UB) [1128] Just any metals.
Andrew (PS1UC) [1129] Erm, oh iron, aluminium, brass, copper, steel, erm magnesium, sodium, potassium, calcium
John (PS1UB) [1130] Great [laugh] Right.
Andrew (PS1UC) [1131] Lithium, er ...
John (PS1UB) [1132] One mentioned earlier, as a catalyst.
Andrew (PS1UC) [1133] Er potassium permanganate No
John (PS1UB) [1134] No.
Andrew (PS1UC) [1135] no, platinum, gold, silver,
John (PS1UB) [1136] Right, okay.
[1137] Lots of them.
[1138] Erm ... some properties of metals that most of the metals, nearly all the metals have?
Andrew (PS1UC) [1139] Conduct electricity.
John (PS1UB) [1140] Right, and if they conduct electricity they also conduct?
Andrew (PS1UC) [1141] ... What else can they [...]
John (PS1UB) [1142] Erm
Andrew (PS1UC) [1143] Heat.
John (PS1UB) [1144] Right
Andrew (PS1UC) [1145] Heat.
John (PS1UB) [1146] Okay. [...]
Andrew (PS1UC) [1147] I was thinking of something like electricity, I'm saying have I missed something [...]
John (PS1UB) [1148] Right.
[1149] Erm they conduct heat and they conduct electricity.
Andrew (PS1UC) [1150] Yeah.
John (PS1UB) [1151] A one foot copper pipe and a one foot sort of piece of fairly thick wooden dowel, and I'm going to stick a blow torch on the end of each one, which one would you [...]
Andrew (PS1UC) [1152] The dowel please.
John (PS1UB) [1153] Yeah, yeah.
[1154] So th the copper will conduct very quickly, it'll soon get hot and [...] the wooden one will be a good insulator.
[1155] Erm metal oxides, metal [yawn] [...] the oxides, differences see, this is the thing they're all sort of quite keen on, so some of the important metals here.
[1156] iron, very important, you know you can't there's can't be a house in the country that you go into and not find something made of iron.
Andrew (PS1UC) [1157] Yeah.
John (PS1UB) [1158] Erm cars, okay they're made of steel but the steel is made from the iron.
[1159] Aluminium, pretty important, also a very good conductor of electricity.
[1160] Erm which is metal is sort of one of the best conductors of electricity?
Andrew (PS1UC) [1161] Er copper.
John (PS1UB) [1162] Yeah copper's a very good one.
[1163] Silver and gold are excellent conductors but they're a bit expensive so I [laugh]
Andrew (PS1UC) [laugh]
John (PS1UB) [1164] you know when [...]
Andrew (PS1UC) [1165] How about platinum?
John (PS1UB) [1166] Yes.
Andrew (PS1UC) [1167] Is that even better?
John (PS1UB) [1168] [...] erm is it better?
Andrew (PS1UC) [1169] Alright.
John (PS1UB) [1170] I don't know actually, I don't know.
[1171] I'd imagine it is
Andrew (PS1UC) [1172] Yeah.
John (PS1UB) [1173] So you've got me there on that one. [laugh]
Andrew (PS1UC) [1174] Mm.
John (PS1UB) [1175] Erm ... Now differences between ... metals and non metals.
[1176] ... What would you say the differences
Andrew (PS1UC) [1177] Between metals and non metals.
[1178] Er non metals don't conduct electricity er
John (PS1UB) [1179] And don't conduct
Andrew (PS1UC) [1180] Heat.
John (PS1UB) [1181] Heat as well
Andrew (PS1UC) [1182] Er
John (PS1UB) [1183] yeah, so you can use them for insulators, electrical insulators or heat insulators, right.
Andrew (PS1UC) [1184] Er metals erm, they're always in solid or liquid form, metals never a gas .
John (PS1UB) [1185] generally, okay apart from mercury they're they're
Andrew (PS1UC) [1186] Yeah.
John (PS1UB) [1187] generally
Andrew (PS1UC) [1188] A solid.
John (PS1UB) [1189] a solid, and erm What other things can you do with metals, thinking if their physical properties.
Andrew (PS1UC) [1190] Erm they're strong
John (PS1UB) [1191] Yeah, they're strong erm
Andrew (PS1UC) [1192] Erm they r they react quite often with water and air.
John (PS1UB) [1193] Yeah.
Andrew (PS1UC) [1194] With water.
John (PS1UB) [1195] Yes and
Andrew (PS1UC) [...]
John (PS1UB) [1196] or air, yeah .
Andrew (PS1UC) [1197] Yeah.
[1198] Erm
John (PS1UB) [1199] What else about Concentrating on their physical properties.
Andrew (PS1UC) [1200] Erm
John (PS1UB) [1201] What could you do with [...] lump of copper.
[1202] There's a big s slab of copper.
Andrew (PS1UC) [1203] Melt it down.
John (PS1UB) [1204] You good melt it, mould it, make shapes out of it.
[1205] What else could you do with it?
Andrew (PS1UC) [1206] Erm
John (PS1UB) [1207] Think perhaps of a piece of lea, what could you do with that ?
Andrew (PS1UC) [1208] It's heavy ... [...] it protects against radiation
John (PS1UB) [1209] Mhm.
Andrew (PS1UC) [1210] [...] erm
John (PS1UB) [1211] Yeah.
Andrew (PS1UC) [1212] There's lots of things you can do with it.
John (PS1UB) [1213] Okay, so erm what would you make wire out of?
Andrew (PS1UC) [1214] Copper
John (PS1UB) [1215] Yeah.
[1216] How do
Andrew (PS1UC) [...]
John (PS1UB) [1217] make wire out of metal?
Andrew (PS1UC) [1218] Er [...]
John (PS1UB) [1219] You get your lump of metal and you stretch it you sort of pull it through a die, through a tiny hole and you just st stretch it.
[1220] Big big thick rod and you pull a little bit of it through a tiny hole and you stretch it out, and you keep stretching it and you keep stretching it, it doesn't
Andrew (PS1UC) [1221] Aha.
John (PS1UB) [1222] snap.
[1223] So it's it's ductile.
Andrew (PS1UC) [1224] Yeah.
John (PS1UB) [1225] erm and it's malleable, you can hammer it, you can hammer it into shapes and panel beat it [...] a car or bits of lead you could dress it, you can tap it with a [...] .
[1226] Mend your roof, things like that.
[1227] So metals
Andrew (PS1UC) [1228] Mhm.
John (PS1UB) [1229] are usually erm they're pretty workable, they're malleable and ductile and erm ... the non metals usually can't do things like that [...] .
[1230] ... Here's your reservoir going down to town, there's a a big drop there they'd normally put it through the turbine and pick up some free electricity [...]
Andrew (PS1UC) [1231] Mm. ...
John (PS1UB) [1232] [reading] Select from the list above the metal that reacts violently with cold water. []
Andrew (PS1UC) [1233] Erm sodium.
John (PS1UB) [1234] Okay.
[1235] [reading] The metal used to make hot water pipes. []
Andrew (PS1UC) [1236] Copper.
John (PS1UB) [1237] [reading] The metal that forms a protective oxide coat when exposed to air and is used in the manufacture of window frames. []
Andrew (PS1UC) [1238] Aluminium.
John (PS1UB) [1239] Right.
Andrew (PS1UC) [1240] Er [reading] the metal that forms two different chlorides [...] solution react with sodium hydroxide solution to give precipitates, one coloured reddish brown the other green. []
[1241] Erm Iron.
John (PS1UB) [1242] So you can work
Andrew (PS1UC) [1243] Yeah.
John (PS1UB) [1244] that one out by what
Andrew (PS1UC) [1245] Yeah.
John (PS1UB) [1246] what have we got left.
[1247] Erm [reading] in a limestone are, the reason [] Now, you know about harness of water?
Andrew (PS1UC) [1248] Temporary hardness.
John (PS1UB) [1249] Temporary and permanent hardness.
[1250] Right ... Now your limestone are [...]
Andrew (PS1UC) [1251] Calcium chloride, isn't it?
John (PS1UB) [1252] Well ... erm ... What does hard water do?
Andrew (PS1UC) [1253] Erm it doesn't so You can't make soap in it.
[1254] Er
John (PS1UB) [1255] Okay when when you use soap you get a load of scum with precipitates, what happens in your water tanks and water pipes in a hard water area ?
Andrew (PS1UC) [1256] Er you get calc erm you get like hard calcium.
John (PS1UB) [1257] Right, you get deposits of calcium something.
Andrew (PS1UC) [1258] Yeah.
John (PS1UB) [1259] It's Your pipes get clogged up and the bore down the middle gets thinner and thinner so the water [...] sort of hardly trickles through.
[1260] So this is something which is insoluble.
Andrew (PS1UC) [1261] Yeah.
John (PS1UB) [1262] Something which seems to be soluble at some stage and the water gets hot and it's not soluble, so we're looking for things here that are not ... not soluble.
[1263] It might be worth having a look at that cos there's near There's very often a question on hardness of water.
[1264] Erm [...] be a good thing for you t Cos you you're really good on all the rest of the
Andrew (PS1UC) [1265] Yeah.
John (PS1UB) [1266] water and what it does, it might be nice to just look at that to finish it off, so that if
Andrew (PS1UC) [1267] Yeah.
John (PS1UB) [1268] get a question on water, which is very common, you get sort of you get the full marks to it.
[1269] So ... hard water doesn't readily form a lather with soap, right?
Andrew (PS1UC) [1270] Yeah.
John (PS1UB) [1271] Erm [whispering] [...] [] this this ... twelve point six ... [reading] the main reason for temporary hardness is that [] okay.
[1272] Twelve point [...] just says B, sorry.
[1273] [...] The calcium hydrogen carbonate or calcium bicarbonate, if you like
Andrew (PS1UC) [1274] Yeah.
John (PS1UB) [1275] Now, what do you think calcium hydrogen carbonate looks like? [...]
Andrew (PS1UC) [1276] It's got calcium, hydrogen and carbon
John (PS1UB) [1277] So it's got
Andrew (PS1UC) [1278] in it.
John (PS1UB) [1279] calcium, hydrogen and carbonate.
[1280] C A H C O three, something like that.
[1281] We're not bothered about the valencies and whether it'll be two C As with one C O three or two C O threes with one C A or how the e But it'll be something like that.
[1282] It's okay in cold water, but when you heat it up it breaks down into the carbonate, C A C O three.
[1283] And the bicarbonate is soluble, but the carbonate, calcium carbonate is just chalk.
Andrew (PS1UC) [1284] Yeah.
John (PS1UB) [1285] And it's not soluble, so as soon as the water heats up, it comes out.
[1286] So you get this in your hot water cylinder, we can get it in boilers, erm you get it in hot water pipes and it happens a lot in in hard water areas, [...] ... [reading] Scale will dissolve in the acid in the bubbles of Twelve point seven.
[1287] Ah here we are.
[1288] This kettle, is covered with scale, now look, see ... Twelve point six is asking you which one of these is causing the problem?
[1289] Right?
[1290] Now ,
Andrew (PS1UC) [1291] Mm.
John (PS1UB) [1292] twelve point seven, because it's in hard water, it's covered with scale, calcium carbonate.
[1293] So maybe you could sort of go back and think [...] which one of these would possibly give me calcium carbonate, well that Good chance it might you know have a guess, that this one
Andrew (PS1UC) [1294] Yeah.
John (PS1UB) [1295] the calcium [...] hydrogen carbonate was the one that [...] .
Andrew (PS1UC) [1296] [...] carbonates in it?
John (PS1UB) [1297] right okay.
[1298] So often you can get it through some related questions and just go back
Andrew (PS1UC) [1299] Yeah.
John (PS1UB) [1300] through it all.
[1301] Have a have a guess, you know.
[1302] [reading] What is hard water? []
[1303] Okay you've you've answered that one.
[1304] [reading] Dilute hydrochloric acid is put in your kettle to remove the scale. []
[1305] How did it What wou what would happen when you poured it in?
Andrew (PS1UC) [1306] Erm
John (PS1UB) [1307] You've got calcium carbonate and you pour an acid on it .
Andrew (PS1UC) [1308] React with it and it bubble Heat up.
John (PS1UB) [1309] It would heat up, yes and it would bubble up.
[1310] And see any fizzing, any effervescence?
Andrew (PS1UC) [1311] Yeah.
John (PS1UB) [1312] What gas would be coming off? [...] carbonate.
Andrew (PS1UC) [1313] Hydrogen carbonate .
[1314] Er what's on the inside of the kettle?
John (PS1UB) [1315] Calcium carbonate, so you've got acid
Andrew (PS1UC) [1316] Chlorine.
John (PS1UB) [1317] Acid plus carbonate.
Andrew (PS1UC) [1318] Yeah.
[1319] Erm ... you'd be getting the chlorine off, getting hydrogen, actually [laugh]
John (PS1UB) [1320] What what what happens when you put Remember when we we [...] looked at, acid and alkali,
Andrew (PS1UC) [1321] Yeah.
John (PS1UB) [1322] acid and base,
Andrew (PS1UC) [1323] Yeah.
John (PS1UB) [1324] and we also looked at acid and carbonate.
Andrew (PS1UC) [1325] Erm
John (PS1UB) [1326] And that was the odd one.
[1327] It gives an extra thing that bubbles off, and what comes out of
Andrew (PS1UC) [1328] Er it's a ga [...]
John (PS1UB) [1329] It's a gas that comes out of a carbonate.
Andrew (PS1UC) [1330] Carbon dioxide.
John (PS1UB) [1331] That's it, okay?
Andrew (PS1UC) [1332] Mm.
John (PS1UB) [1333] Right?
Andrew (PS1UC) [1334] Mm.
John (PS1UB) [1335] Okay so we get the carbon dioxide given off and [reading] name two products [] .
[1336] Yet another [...] for that.
[1337] [reading] Explain why dilute hydrochloric acid not be remove used to remove the scale from aluminium kettles. [] ...
Andrew (PS1UC) [1338] Erm it will react with the aluminium, eat away at the aluminium.
John (PS1UB) [1339] Right it erm al aluminium is a very reactive element.
[1340] Although we use it cos it doesn't rust, it does.
[1341] It rusts so quickly and so sort of firmly it forms a very thin film of aluminium oxide on the surface .
Andrew (PS1UC) [1342] It takes something like ten or five or ten seconds when you made it.
John (PS1UB) [1343] It's bonded on tight to the surface and it stops any more air getting and oxidizing the rest of the aluminium, so [...] we take that off with the acid and let the acid react with the aluminium [...] nice hole in it
Andrew (PS1UC) [1344] When we use it in school , in When you've scrapped some off the layer [...] you can't touch otherwise your fingerprints will be all over it.
John (PS1UB) [1345] Right.
Andrew (PS1UC) [1346] Until it's oxidized.
John (PS1UB) [1347] Yeah, yeah.
[1348] Okay that's good.
[1349] Erm bit of chrome plating.
[1350] Ho Any idea how you would chrome plate car bumper?
Andrew (PS1UC) [1351] No.
[1352] [...] I've always wanted
John (PS1UB) [1353] how would you how would you copper plate things.
Andrew (PS1UC) [1354] Erm electrolysis, [...]
John (PS1UB) [1355] Same thing for chrome.
Andrew (PS1UC) [1356] Yeah.
John (PS1UB) [1357] And when they silver plate things what they tend to do I mean first th the thing When you plate something erm it follows the shape.
[1358] So if you've got something rough, and you plate it, erm you get a rough finish.
[1359] If you want a nice shiny smooth finish you polish
Andrew (PS1UC) [1360] Polish.
John (PS1UB) [1361] the thing you're going to plate first.
[1362] And what they used to do is they [...] say coat it with silver, they might coat it with copper first.
[1363] So get it smooth, coat it with copper, polish that up a bit so it's really nice and shiny and put a fine coating of silver over it
Andrew (PS1UC) [1364] Yeah.
John (PS1UB) [1365] and you're saving a bit
Andrew (PS1UC) [...]
John (PS1UB) [1366] on the expense.
[1367] Same with gold plating and stuff like that.
Andrew (PS1UC) [1368] Quite often you use gold leaf though don't they?
[1369] And
John (PS1UB) [1370] Yeah.
Andrew (PS1UC) [1371] gold plating.
John (PS1UB) [1372] Yes.
[1373] Er don't know which is more expensive, actually.
[1374] Carbonates.
[1375] Why why is carbon important?
[1376] Why why do you think we might be interested in carbon?
Andrew (PS1UC) [1377] Erm ... it's around [...] it comes out of a lot of things.
[1378] erm car exhausts
John (PS1UB) [...]
Andrew (PS1UC) [1379] etcetera, when you burn things.
John (PS1UB) [1380] Yeah.
[1381] What's the difference One good reason why we would be interested in it.
[1382] What's the difference th One of the big difference between organic and inorganic chemistry?
[1383] The chemistry of sort of life, organic chemistry how things grow and how we work.
Andrew (PS1UC) [1384] Yeah, er carbon's in both of them.
John (PS1UB) [1385] Mm.
[1386] A lot of We get the complicated carbon compounds ... in erm all the natural processes.
[1387] So we gonna look at it in simple form first, things like carbon dioxide and carbon monoxide and carbonates and then build up erm [...] I think, no.
[1388] [sneeze] Pardon me.
[1389] Erm why is carbon dioxide useful in a fire extinguisher?
Andrew (PS1UC) [1390] Carbon dioxide?
John (PS1UB) [1391] Mm.
Andrew (PS1UC) [1392] Erm it smothers the flames they can't get oxygen if there's carbon dioxide around.
John (PS1UB) [1393] Yep.
Andrew (PS1UC) [1394] Chokes it.
John (PS1UB) [1395] Right, how about some more some more ... did wh wh what's graphite?
[1396] [yawn] And what's diamond?
Andrew (PS1UC) [1397] They're all compounds They're crushed together.
John (PS1UB) [1398] They're forms of carbon.
Andrew (PS1UC) [1399] Oh right, yeah.
John (PS1UB) [1400] [whispering] Okay. []
[1401] Allotropes of carbon.
[1402] Erm a carbonate plus an acid gives? []
Andrew (PS1UC) [1403] Erm an acid.
[1404] Carbonate plus an acid?
John (PS1UB) [1405] Right, like we poured stuff
Andrew (PS1UC) [1406] Salt and water.
John (PS1UB) [1407] Gives a salt and a water and
Andrew (PS1UC) [1408] [...] carbon dioxide.
John (PS1UB) [1409] Right, okay, and it gives you sort of three boxes to put things in there, okay?
[1410] Great.
[1411] So you get your full marks from that.
[1412] ... Few more things ... Mm ...
Andrew (PS1UC) [...]
John (PS1UB) [1413] Nitrogen okay it's fairly important because of production of ammonia and nitric acid and basis for the chemi chemical industry.
[1414] Here's the n here's the nitrogen cycle which I thing you're pretty good at, okay on that
Andrew (PS1UC) [1415] Mm.
John (PS1UB) [1416] aren't you?
[1417] Tell me tell me some of the bits in the nitrogen cycle then, go on.
Unknown speaker (FMRPSUNK) [1418] What bits?
John (PS1UB) [1419] The lot [laugh]
Andrew (PS1UC) [1420] Lots of bits.
John (PS1UB) [1421] The lot tell me he lot .
Andrew (PS1UC) [1422] I c I don't I don't think I can tell you the lot it's
John (PS1UB) [1423] Tell me some bits then and [...] work out Could you draw a picture of
Andrew (PS1UC) [1424] [laugh] Mm no! []
[1425] I don't think I know it that well .
John (PS1UB) [1426] It's go It's a good, you know
Andrew (PS1UC) [1427] Er
John (PS1UB) [1428] it's a fairly common question.
Andrew (PS1UC) [1429] I know erm
John (PS1UB) [1430] The nitrogen cycle.
[1431] Have a have a have a go at some of them.
Andrew (PS1UC) [1432] [...] I don't know where to start, hang on just need to
John (PS1UB) [1433] Well okay, where where're you going to start.
Andrew (PS1UC) [1434] Can't you just ask me about it?
[1435] It's
John (PS1UB) [1436] Well it This is more like what an [...]
Andrew (PS1UC) [1437] I don't I don't really know it well enough to tell you what a nitrogen cycle [...] .
John (PS1UB) [1438] Erm where does it come from, where does it go to, who gives it out, who takes it in?
[1439] Things like that.
Andrew (PS1UC) [1440] Erm [...] Can't even remember what it is now.
John (PS1UB) [1441] Okay have have look at the nitrogen cycle,
Andrew (PS1UC) [1442] Yeah.
John (PS1UB) [1443] sort of read through a bit about it and then when you've read it, put the book away and leave it for half an hour or an hour or something and then try and draw a rough outline of some of the main points.
[1444] Some of them some of them give a lot of details, I mean this gives a lot of detail there.
[1445] You may not need ... as much as that, but erm Bacteria, nitrates in the soil and the plants taking up the nitrates some of the plants.
[1446] Do you know any plants that put nitrogen back into the soil? ...
Andrew (PS1UC) [1447] No.
John (PS1UB) [1448] No, erm [...] plants people tend to grow peas and beans and things cos they form little nodules round their roots, and they're putting nitrogen They store nitrogen in that and they sort of When they've finished they put nitrogen back into the soil.
[1449] Right oxygen and sulphur.
[1450] Ooh got through got through nearly the whole syllabus there in in one lesson.
Andrew (PS1UC) [1451] Mm.
John (PS1UB) [1452] The halogens, do you know what they are?
Andrew (PS1UC) [1453] Er, gases erm
John (PS1UB) [1454] Okay good.
[1455] [...] Erm
Andrew (PS1UC) [1456] Argons [...] ring a bell No, nitrogen.
John (PS1UB) [1457] Chlorine?
Andrew (PS1UC) [1458] Yeah.
John (PS1UB) [1459] Chlorine, bromine, iodine
Andrew (PS1UC) [1460] Yeah.
John (PS1UB) [1461] are the three main ones.
[1462] That one, [...] that's gonna be
Andrew (PS1UC) [1463] Yeah.
John (PS1UB) [1464] or just about it.
Andrew (PS1UC) [...]
John (PS1UB) [1465] What's happening in a blast furnace?
[1466] Erm draw your picture, work out what happens.
[1467] What you put in what you get out.
[1468] Why do they need coke?
[1469] What's what's the pur What does the coke do, to the iron?
Andrew (PS1UC) [1470] Heat.
John (PS1UB) [1471] It's carbon, it's not being used as a fuel it's just being chucked in, to do something with the with the iron ore and why does it put limestone in it?
[1472] So ... something to look at there.
[1473] [...] test
Andrew (PS1UC) [...]
John (PS1UB) [1474] Bar chart.
[1475] Can you read a bar chart?
Andrew (PS1UC) [1476] [laugh] Yeah [...] oh no.
John (PS1UB) [1477] [laugh] Yes you can. []
[1478] Okay read that one then, as you say As you claim you can't read it.
Andrew (PS1UC) [1479] Oh right.
[1480] That one is seventy
John (PS1UB) [1481] Mhm.
Andrew (PS1UC) [1482] million tonnes.
[1483] that one is seventy two million
John (PS1UB) [1484] Good ,
Andrew (PS1UC) [1485] tonnes.
John (PS1UB) [1486] right.
[1487] [reading] In nineteen eighty three, the yearly consumption was found to be seventy six million tonnes, so where would you mark that?
Andrew (PS1UC) [1488] So that one will be s that'll be seventy four, so in nineteen
John (PS1UB) [1489] nineteen eighty three, mark it on the chart.
Andrew (PS1UC) [1490] [...] seventy [...]
John (PS1UB) [1491] Don't actually mark it on that but
Andrew (PS1UC) [1492] Yeah I won't.
John (PS1UB) [1493] you can Right so.
[1494] I mean that's [laugh]
Andrew (PS1UC) [1495] Yeah.
John (PS1UB) [1496] It's [...] isn't it?
Andrew (PS1UC) [1497] Yeah.
John (PS1UB) [1498] Right.
[1499] Ooh.
Andrew (PS1UC) [1500] My maths papers are the worst for that.
John (PS1UB) [1501] Yeah.
[1502] ... Alright, well the They give you the answer for those of you who couldn't do it.
Andrew (PS1UC) [1503] Yeah.
John (PS1UB) [1504] Okay, organic chemistry.
[1505] Now we did have a little bit of that, I would say er leave it leave it till you've got the other stuff pretty well sorted out .
Andrew (PS1UC) [1506] Yeah.
John (PS1UB) [1507] Erm pie chart.
[1508] Can you read a pie chart?
[1509] How much how much is used for making [...] and polyethylene and things?
[1510] I mean so even something's like this on the organic, you might not have a clue what polyethylene is or polypropylene or anything else, but you can read the pie chart and work out what what's going on.
[1511] So you could still pick up some [...] What's the last hurdle?
[1512] I'm interested in this, what does it say?
[1513] Of test questions ... Er yeah, these are these are tricky, where they give you something like They give you a melting point and a boiling point whether it conducts electricity and a gas is given off which turns limewater milky.
Andrew (PS1UC) [1514] Carbon dioxide.
John (PS1UB) [1515] Right, so if it gives of If you heat it in er and it gives of carbon dioxide, have a guess at what it is that we're heating?
Andrew (PS1UC) [1516] Erm hydrochloric acid.
[1517] [...] acid, er no
John (PS1UB) [1518] W w we're not putting an acid with it
Andrew (PS1UC) [1519] Yeah.
John (PS1UB) [1520] we're just heating this thing, so
Andrew (PS1UC) [1521] Er
John (PS1UB) [1522] what's it got to contain if it
Andrew (PS1UC) [1523] Carbon and oxygen.
Andrew (PS1UC) [1524] So what compounds do you know that have carbon and oxygen in it.
Andrew (PS1UC) [1525] Er
John (PS1UB) [1526] The ones that gave of carbon dioxide when we put an acid to them.
Andrew (PS1UC) [1527] Er calcium er erm Oh hydrogen carbonate.
John (PS1UB) [1528] Okay, calcium carbonate, yes.
Andrew (PS1UC) [1529] Yeah.
John (PS1UB) [1530] So the carbonates, any of the carbonates, heat them you get a good chance of getting the ... carbon dioxide given off.
[1531] Okay.
[1532] So even these more awkward ones you can still you can still have a good guess at them, just from what you know.
[1533] ... Nothing else.
[1534] What about this one?
[1535] Erm [...] acid in rain coming in again.
[1536] [reading] From the chemicals listed below, which one produces acid rain?
[1537] Carbon, carbon monoxide, chlorine, hydrogen, plus sulphur dioxide.
Andrew (PS1UC) [1538] [...] .
John (PS1UB) [1539] [...] [reading] Iron is obtained using a blast furnace.
[1540] The raw materials that go in at the top are iron ore, limestone and [] What else goes in there? ...
Andrew (PS1UC) [1541] [...] .
John (PS1UB) [1542] Okay.
Andrew (PS1UC) [1543] Limestone and coke.
John (PS1UB) [1544] Right, coke.
[1545] Although it might be a temptation to say hot air, because you do put hot air in, but it says goes in at the top of the furnace.
Andrew (PS1UC) [1546] Yeah.
John (PS1UB) [1547] So, watch out for that one, again people might [...] think [...] lime or something, get it confused with limestone, so it's really a bit tricky that.
[1548] Coke.
[1549] ... Right, do you happen to know the erm ... three main ingredients of gunpowder?
Andrew (PS1UC) [1550] Er sulphur, charcoal and saltpetre which is
John (PS1UB) [1551] Very good.
Andrew (PS1UC) [1552] erm, what is it?
[1553] They use it in fertilizers as well
John (PS1UB) [1554] Mhm.
John (PS1UB) [1555] but can't remember its proper name.
[1556] Erm, what is it?
[1557] Can't remember.
John (PS1UB) [1558] Tell you what salt peter is.
Andrew (PS1UC) [1559] Mhm.
John (PS1UB) [1560] Salt peter is sodium nitrite.
Andrew (PS1UC) [1561] Yeah.
John (PS1UB) [1562] And er nitrate, mm, a chile saltpetre.
[1563] I it's it's very similar in properties to saltpetre, and it comes from Chile.
[1564] And we used to get it from Chile.
[1565] And it's potassium instead of sodium.
Andrew (PS1UC) [1566] Yeah.
John (PS1UB) [1567] Erm, yeah, very good.
[1568] [reading] Gunpowder is not used in rifles because it produces smoke an leaves a residue in the barrel. []
Andrew (PS1UC) [1569] Yeah.
John (PS1UB) [1570] So there's the er equation.
[1571] ... What happens when it burns or explodes, so the ... okay, the potassium nitrate and the carbon and the sulphur burn and they give quite a bit of er C O two.
[1572] they also th These other things can all burn as well and you can get erm sulphur dioxide and you can get, as well as nitrogen you can get oxides of nitrogen.
[1573] And you get a lot you get a lot of gas formed, which is why you get the big explosion.
[1574] It's formed very quickly.
[1575] ... And there's a slightly more complicated one, what happens when nitroglycerine explodes.
Andrew (PS1UC) [whistles]
John (PS1UB) [1576] But the big thing is, okay, you get a lot of water
Andrew (PS1UC) [...]
John (PS1UB) [1577] lot of water which is going to come out as steam.
Andrew (PS1UC) [1578] Mm.
John (PS1UB) [1579] A lot of nitrogen as a gas, I mean ten H two O as a gas.
Andrew (PS1UC) [1580] So you're gonna need air [...]
John (PS1UB) [1581] Bang.
[1582] N Yeah.
Andrew (PS1UC) [1583] You're gonna air t You need how much?
[1584] We we don't actually We've got It's got nine oxygen in it already, right so this one doesn't actually need any air.
[1585] We're not putting any oxygen in the ox It's got nine oxygens tied up with that already to make all these other things from, so we've got a lot of volume of gases there.
Andrew (PS1UC) [1586] Mhm.
John (PS1UB) [1587] Six N twos, an O two and ten H two Os.
Andrew (PS1UC) [1588] Yeah.
John (PS1UB) [1589] Bang!
[1590] Erm this this one [tape change]