Hey there! Sign in to join this conversationNew here? Join for free
    Offline

    3
    ReputationRep:
    (Original post by Mr.bob)
    Why 12.5 and not 25?
    because it was when the titration was half way through
    • Thread Starter
    Offline

    12
    ReputationRep:
    (Original post by CERC)
    because it was when the titration was half way through
    Did it not say in the question that though at the Equivalence point the concentration of the salt was equal to the concentration of acid
    Offline

    1
    ReputationRep:
    No it said when the [salt] is the same as the [acid] then the titration is half complete, it was a 1:1 ratio so when 12.5 cm3 has been added half of the acid was used up and half of the salt had formed. Also I googled the acid in question and it's pKa is 2.5
    • Thread Starter
    Offline

    12
    ReputationRep:
    (Original post by Nathanbh321)
    No it said when the [salt] is the same as the [acid] then the titration is half complete, it was a 1:1 ratio so when 12.5 cm3 has been added half of the acid was used up and half of the salt had formed. Also I googled the acid in question and it's pKa is 2.5
    I am such a fool how did i misrewd the question like that. The worst thing is i knew about how at half neutralisation(i.e. the tutration is half done) the conc of salt = conc of acid but i put my belief in how i read the question
    Offline

    1
    ReputationRep:
    I wouldn't worry about it it was only 2 marks and you'd most likely get a method mark for 10^(-pKa)
    Offline

    1
    ReputationRep:
    Got 264.4mg or something for the saponification question
    Offline

    1
    ReputationRep:
    So did I and most others in the class, fairly confident that's right.
    Offline

    1
    ReputationRep:
    (Original post by Nathanbh321)
    So did I and most others in the class, fairly confident that's right.
    Yeah some people in my school either got it or forgot to divide by 9 so I am sure this is right
    Offline

    3
    ReputationRep:
    how much revision has everyone done for the next one? ive just done amines and trying to learn arenes at the minute.

    was everyone able to do the polymer question? i completely forgot how to do it so left it out?
    also, for the question where you had to draw the possible structures for the fat worth three marks, did people say it had or hadnt an asymetric centre? I said it didn't!
    Offline

    1
    ReputationRep:
    (Original post by CERC)
    how much revision has everyone done for the next one? ive just done amines and trying to learn arenes at the minute.

    was everyone able to do the polymer question? i completely forgot how to do it so left it out?
    also, for the question where you had to draw the possible structures for the fat worth three marks, did people say it had or hadnt an asymetric centre? I said it didn't!
    I drew two possible structures and labelled them as either optically active or optically inactive. However I said it was optically active in the question below
    Offline

    1
    ReputationRep:
    For the polymer it was addition polymerisation, the c=c bond opened out. Yeah one isomer was and one wasnt, the one with two adjacent oleic acid molecules was, you did have to remove the Carbon and hydrogens from the formula when doing the residual groups though
    Offline

    3
    ReputationRep:
    hey! can someone explain to me how you get an A* at chemistry.I have a high A from AS and I think I did ok in the practical this year. Im pretty sure that ive messed up A2 unit 1 but if I did exceptionally well in the next test could I still get an A*?
    Offline

    1
    ReputationRep:
    In order to get an A*, you need to have 90% overall at A2. I am thinking the A* boundary for unit 1 will definitely be below 90/120, the scaling will help us all
    Offline

    3
    ReputationRep:
    (Original post by Binajd)
    In order to get an A*, you need to have 90% overall at A2. I am thinking the A* boundary for unit 1 will definitely be below 90/120, the scaling will help us all
    yes, but if you do really badly in one exam but say brilliantly in the rest, then what then???

    sorry, its just i really had my heart set on an A* in chemistry and want to know if there is still a chance
    Offline

    1
    ReputationRep:
    (Original post by CERC)
    yes, but if you do really badly in one exam but say brilliantly in the rest, then what then???
    If you do really badly as in it would prevent you in getting 270/300 at A2, you won't get an A*. However, if you got a low B but really good A* scores in others to get it above 270/300, you will get an A*
    Offline

    3
    ReputationRep:
    (Original post by Binajd)
    If you do really badly as in it would prevent you in getting 270/300 at A2, you won't get an A*. However, if you got a low B but really good A* scores in others to get it above 270/300, you will get an A*
    thank you
    Offline

    1
    ReputationRep:
    (Original post by Binajd)
    In order to get an A*, you need to have 90% overall at A2. I am thinking the A* boundary for unit 1 will definitely be below 90/120, the scaling will help us all
    No way it'll be that low, far easier than last years. But still difficult so I'd say 98-102 for an A*
    Offline

    3
    ReputationRep:
    (Original post by Nathanbh321)
    No way it'll be that low, far easier than last years. But still difficult so I'd say 98-102 for an A*
    last year's A2 or AS?
    Offline

    1
    ReputationRep:
    (Original post by CERC)
    last year's A2 or AS?
    A2 1 which was 91 for an A* and thee lowest it's been. It's normally between 102-108 for an A*.
    Offline

    0
    ReputationRep:
    I honestly think this years paper was more difficult than last years, by a good bit.
    I didn't get either of the equations for the potassium chloroethanoate that question was horrible!
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    What's your favourite Christmas sweets?
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.