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    (Original post by jirapat121)
    i think you have to leave it as 715 despite that 50000/70 =714.285 because 714 monomers will not make Mr=50000 they will only make polymers with Mr=49980 but I think they will still allow 714 : )
    Crap I wrote 714 because I left it in 3.s.f :|
    Really hope they accept it :|
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    (Original post by fastandfurious)
    Crap I wrote 714 because I left it in 3.s.f :|
    Really hope they accept it :|
    Yeah I think they will accept it because last year there was literally the same question asking to do the same calculations and I looked at the mark scheme of the last year paper and it said allow 1 lower than the answer
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    (Original post by nadrxj)
    Anyone else get something like 14g for the percentage yield question?
    I got 11.1 g by doing mass of product/0.45
    What did you do?
    Wait dw i see where i went wrong. I should have done 11.1/mr of product then * that by Mr of reactant
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    (Original post by NervousBoy)
    This is what I remember from my calculations.

    Magnesium Mass : 0.38 g or something along that

    CO +1602
    Volume: 259.09 Litres
    Enthalphy of Nonane: -230 something
    Enthalphy of Reaction using Temp change: -34.7 or similar
    Repeat Units: 50000/70

    Let me know what you guys got
    Exactly the same. Go us
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    What did people get for the last question?

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    (Original post by Hunnybeebee)
    What did people get for the last question?

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    The two Haloalkanes were CH3CH2CH2Br and CH3CHBrCH3

    Then reacted with NaOH/reflux to form propan-1-ol and propan-2-ol

    propan-2-ol reacted with the carboxylic acid to form an ester:

    R-COOCH(CH3)2 (can't remember what the carboxylic acid was)
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    (Original post by Hunnybeebee)
    What did people get for the last question?

    Posted from TSR Mobile
    Part 1:
    C3H7Br
    Different isomers were just the Br being on a different carbon

    Part 2:
    C3H7OH
    E is a primary alcohol
    F is a secondary alcohol
    G is a carboxylic acid

    Part 3:
    Ester is formed.
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    How the hell did I get 2 point something gram on the percentage yield question TOT
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    (Original post by Hunnybeebee)
    I calculated it and looked at the decimal place so rounded down. Hopefully the twitter account will upload the paper tonight may be!

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    hey whats the twitter account username?
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    (Original post by jirapat121)
    How the hell did I get 2 point something gram on the percentage yield question TOT
    I got 2 point something and so did my friends. It was a 45% percentage yield and I had time at the end so I checked and it seemed to work


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    Would some explain to me how they got there answer for the litres one??
    I got 40.1 which is wrong

    I think I worked out:
    - Moles of c02
    - did stoichiometry 1:8 ratio
    - then worked out litres after I found the Grams???
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    (Original post by AJtheconfusedcat)
    hey whats the twitter account username?
    It's @ChemistryALevel.
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    (Original post by fastandfurious)
    It's @ChemistryALevel.
    they said yesterday they're not allowed to or something
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    (Original post by Lion2121)
    Would some explain to me how they got there answer for the litres one??
    I got 40.1 which is wrong

    I think I worked out:
    - Moles of c02
    - did stoichiometry 1:8 ratio
    - then worked out litres after I found the Grams???
    Not sure if I got it right but I worked out the moles of CO2 and then compared it to the octane which was 8 times less, so I divided the moles by 8 to get the moles of octane. I then found the mass in g by multiplying the moles by the Mr and then divided it by the value (I think it was 700?) to find the litres. I got 200 and something, can't remember the exact figure.

    Not sure if it's right as maths is not my strong point but that was my thought process!


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    What did everyone get for the enthalpy mcat thing??? I got -317 something like that
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    (Original post by NinjaOtter)
    Part 1:
    C3H7Br
    Different isomers were just the Br being on a different carbon

    Part 2:
    C3H7OH
    E is a primary alcohol
    F is a secondary alcohol
    G is a carboxylic acid

    Part 3:
    Ester is formed.
    Beautiful

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    (Original post by emem2011)
    Not sure if I got it right but I worked out the moles of CO2 and then compared it to the octane which was 8 times less, so I divided the moles by 8 to get the moles of octane. I then found the mass in g by multiplying the moles by the Mr and then divided it by the value (I think it was 700?) to find the litres. I got 200 and something, can't remember the exact figure.

    Not sure if it's right as maths is not my strong point but that was my thought process!


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    I must have got the conversion to litres wrong....

    I'm sure il only drop a mark for that though
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    (Original post by Lion2121)
    I must have got the conversion to litres wrong....

    I'm sure il only drop a mark for that though
    Yeah honestly you won't lose more than one mark as you had all the hard stuff right


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    Idea on grade boundaries guys lol. Some few recent years on

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    (Original post by jirapat121)
    How the hell did I get 2 point something gram on the percentage yield question TOT
    I got 2 point something too at the beginning but then I think I got 12 afterwards(or maybe 14 lol don't remember)
    You're suppose to do 5.00g/68 to get the mols
    (If 68 is the Mr of the product) then divide it 0.45 (45%/100) and then times the Mr of the reactant to get the mass.
    I could be wrong though!
 
 
 
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