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OCR Salters Chemistry F335 12th June 2013 Exam revision thread Watch

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    For the radical question, did people get
    Initiation : CH4 --> CH3 + H

    Termination: CH3 + CH3 --> C2H6
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    (Original post by super121)
    I worked out the moles of iodine that didn't react and took it away from the iodine that could have reacted, them worked out the mass of iodine. That was for 0.2g of oil so I then multiplied it by 500


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    Hmm.. I did a different method, which was longer but easier for me to understand. I worked out the no moles in 0.2g of the oil (had to obtain the molecular formula of the oil to work out its Mr which I got as 878), so I worked out the no moles of I2 that would react with this (multiplied by 6 because of 6 carbo carbon double bonds) and then divided this by the Mr of I2 which is around 250 or something.. so now I have the mass of iodine reacting with. 0.2 of oil.. then I multiplied by 500 to get the mass of iodine reacting with 100g.. which I got as around 173. someone tell me where I have gone wrong here (if 180 is right)
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    What was the answer to the Cac03 seashells thing?
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    (Original post by A.Mustapha)
    For the radical question, did people get
    Initiation : CH4 --> CH3 + H

    Termination: CH3 + CH3 --> C2H6
    Yup I got that! That was a very nice question tbh
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    (Original post by abzy1234)
    Yup I got that! That was a very nice question tbh
    Ah thank god had to think back to last year for the answer
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    Guys, I'd hate to disappoint but it might be a while while I remember what the reactant looked like. I remembered a few minutes ago but forgot *blush*
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    (Original post by suncake)
    I drew the dot on the wrong side of my radicals D: Reckon I'd get penalised?

    I related it to both equations and equilibrium positions moving but it ended with their shells dissolving, yes.

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    ooo i don't think so!

    and what did people get for that NMR question on oxidising methanol???
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    For the nmr question did anyone put methanal?
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    What is the Ka of methanoic acid???
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    (Original post by A.Mustapha)
    Ah thank god had to think back to last year for the answer
    I was lucky I retook F332 last week, so it was still fresh in my mind
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    What did you guys get for the CaCO3 thing. Didnt it say acidity increased or something?
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    (Original post by chemistryfailure)
    For the nmr question did anyone put methanal?
    I did!

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    (Original post by calmpeach)
    ooo i don't think so!

    and what did people get for that NMR question on oxidising methanol???
    I got single peak because there only one proton environment , cause its methanal


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    (Original post by Harantony)
    Oh darn it I halved the concentration for the equilibrium constant question too!

    I could draw the mechanism if people want. Just ask me and I'll send you a PM (I don't want to worry anyone).
    Can you PM it to me please?

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    (Original post by ActaNonVerba)
    Hmm.. I did a different method, which was longer but easier for me to understand. I worked out the no moles in 0.2g of the oil (had to obtain the molecular formula of the oil to work out its Mr which I got as 878), so I worked out the no moles of I2 that would react with this (multiplied by 6 because of 6 carbo carbon double bonds) and then divided this by the Mr of I2 which is around 250 or something.. so now I have the mass of iodine reacting with. 0.2 of oil.. then I multiplied by 500 to get the mass of iodine reacting with 100g.. which I got as around 173. someone tell me where I have gone wrong here (if 180 is right)
    But we didn't know the Mr of the oil, and the skeletal structure on the page before wasn't of the oil (I checked as I was gonna do it that way). I defo think you'll get some marks for your working out though.


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    So in the Iodine question I found the number of moles left over, took that away from the total number of moles of iodine, then calculated the mass of iodine for that number of moles, but for the mass calculation I did Mass = Moles/RFM for some reason...then I scaled up my mass value for 100 grams of the oil, so I got the wrong answer. How many marks out of 5 would I get for that do you think?
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    I did the moles in 100g and then the moles of thiosulfate and divided this value by 2 (2:1 mole ratio) then subtracted to get moles reacted and then multiplied this by Mr of I2. God I'm so stupid!!
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    (Original post by chemistryfailure)
    For the nmr question did anyone put methanal?
    Haha love the name, umm did you have to state the product??? cus I put the type of proton (C-CH) and said no splitting occurs cause it neighboured C=O that carried no H atom.
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    (Original post by calmpeach)
    ooo i don't think so!

    and what did people get for that NMR question on oxidising methanol???
    Methanal. Only one proton environment due to the H-C=O environment?

    I was really happy with the analysis questions. No tricky NMR or IR, and GLC and mass spec were really good I felt! Did people get Methanol for the mass speccy question?
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    (Original post by chemistryfailure)
    For the nmr question did anyone put methanal?
    Didn't it ask for the formula?


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