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    Hi there, We'll go ahead and create the unofficial mark scheme, just post the answers and the most agreed ones shall be updated for it.

    Please Correct any wrong answers and good luck with the rest of your exams.

    If anyone can remember the question numbers and which questions were under which number, that would be great thanks.
    --------------------------------------------
    Question 1:

    Moles of reactants at eqbm 1.6 and 0.2 (2)
    Write a KC expression [G]^2/[E] x [F]^2 (1)
    Kc units mol^-1 dm^+3 (1)
    Kc value 0.30 (3)
    How does G conc change if vol increases, G decreases equ moves to left to raise pressure (3)
    T1 was higher than T2, exothermic eq to right to oppose temp decrease (3)

    Question 2:

    What is weak acid slightly dissociated (1)
    PH of Caoh2 12.38 (3 or 4)
    Mass of carboxy salt 1.09g (5)
    pH acid 3.06 (3)
    Ka expression (1)
    equation of carboxylic acid with Na2CO3 gives salt, water and CO2 (1)
    CO2 in air (1) Aqueous CO2 is acidic, H+ react with OH-, less OH-. (3)


    Order A 2, Order B 0 (2)
    k constant is 5.05 (3)
    new rate 8.3x10^-6 (1)

    Aldehyde Question:

    Nucleophillic addition
    Mechanism: CN- , lone pair arrow to carbon, one bond from C=O dissociates to C-O- with a lone pair, positive hydrogen, arrow from O lone pair to hydrogen.
    Draw the two enantiomers which could form
    Distinguish enantiomers: Each rotates a plane of polarised light, one shall do so clockwise, the other anti clockwise, they rotate in opposite directions.
    Name it: 2-Hydroxybutanenitrile
    Why is reaction slow with HCN? Low Ka, low amount of dissociation, so low amount of CN- available to react.

    Amino acid question:
    Excess of HCl : NH2 groups become NH3+
    Excess of NaOH: COOH groups become COO-
    Methanol with small amount of H2SO4 : COOH becomes COOCH3 Ester? Did anybody make the NH2 groups NH3+ due to the H2SO4 added?






    IM force in kevlr is h bond (1)
    NH3 lone pair repelled by benzene ring (2)
    Mech is electrophilic sub with con hno3 and h2so4 reacting to make NO2+ (6) Sn and HCl reducing NO2 (1)

    nucl add elim with OH attacking cocl carbon a was 20-50ppm and carbon b was 50-90ppm (7)
    repeating unit of this was straight chain polyester ? (1)
    it was condensation polymer (1)
    use Br2/bromine water, benzene no reaction decolourises (Red-Brown to Colourless) with cyclohexene (3)
    ester 1 was the spectrum, 4.1ppm was ch2 with 3 h on adjacent c, next to O-C=O so shifted downfield, other quartet had 2.1-2.6ppm (4)
    quaternary ammonium (bromide) salt, nucl sub with CH3Br in excess (4)
    use tollens, nothing with J, K silver mirror, J has 2 peaks K has 4 (5)

    Final Question: Isomers of C5H8O2
    L. Methyl 2-methylpentanoate:
    M. Ester which exhibits E-Z stereoisomerism :
    N. Carboxylic acid that is branched that shows no optical activity :
    P. Carboxylic acid that shows optical activity
    Q. Cyclic structure that has one ketone group and has 2 peaks in its 1H n.m.r.:
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    Thank you..but how about other questions??
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    Very last question was the isomer ones.

    Molecular formula: C5H8O2

    Draw the structures of

    I. Methyl 2-methylpentenoate
    Ii. Carboxylic acid that is branched that shows no optical activity
    Iii. Carboxylic acid that shows optical activity
    Iv. (Can't remember this one)
    V. Cyclic structure that has one ketone group and has 2 peaks in its 1H n.m.r
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    wast the new rate 9. something?
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    CO2 in air (1) Aqueous CO2 is acidic, H+ react with OH-, less OH-. (3)

    For this question is it 3 marks in total or 4?!
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    Don't know why my kc was 5069.xxxx
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    I have not realisied that the last question required cyclic structure
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    You forgot the optical isomer question and how would you tell them apart


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    (Original post by mynameisntbobk)
    Very last question was the isomer ones.

    Molecular formula: C5H8O2

    Draw the structures of

    I. Methyl 2-methylpentanoate
    Ii. Carboxylic acid that is branched that shows no optical activity
    Iii. Carboxylic acid that shows optical activity
    Iv. (Can't remember this one)
    V. Cyclic structure that has one ketone group and has 2 peaks in its 1H n.m.r
    1. CH2=C(CH3)-COOCH3
    2. CH2=C(COOH)-CH2CH3
    3. CH(CH3)(COOH)(CH=CH2)
    4.
    5. the structure of cyclohexane but with only 5 carbons and an O replacing the 6th carbon. Ketone group opposite the O to give to peaks.
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    (Original post by mynameisntbobk)
    Very last question was the isomer ones.

    Molecular formula: C5H8O2

    Draw the structures of

    I. Methyl 2-methylpentenoate
    Ii. Carboxylic acid that is branched that shows no optical activity
    Iii. Carboxylic acid that shows optical activity
    Iv. (Can't remember this one)
    V. Cyclic structure that has one ketone group and has 2 peaks in its 1H n.m.r
    The 2nd Isomer it was an ester that exhibited E-Z stereoisomerism.
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    I didn't round up my Kc value, do I lose a mark?
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    (Original post by The Lawful T.J)
    The 2nd Isomer it was an ester that exhibited E-Z stereoisomerism.
    Loool I think I skipped that one. Which means I probably mislabelled the others
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    Ka acid question on why hcn not used
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    new rate 8.3x10^-6 (1) why was it this? Changing the volume changes the pressure therefore doesn't effect k? So i put down the same answer 5.05. Doesn't only temp effect value of k
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    The aldehyde question?

    -5 marks for nucleophilic addition

    -2 marks for drawing the enantiomers - mirror images

    -2 marks for distinguishing between enantiomers - rotate plane polarised light in opposite directions

    -1 mark for naming the product of the mechanism - 2-hydroxybutanenitrile (?)

    -2 marks for why HCN reacts slowly - small Ka so HCN is a weak acid therefore partially dissociates, so less nucleophile available.



    Posted from TSR Mobile
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    (Original post by faddys123)
    new rate 8.3x10^-6 (1) why was it this? Changing the volume changes the pressure therefore doesn't effect k? So i put down the same answer 5.05. Doesn't only temp effect value of k
    Change in volume = change in conc = change in rate
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    (Original post by MuzzyYT)
    Hi there, We'll go ahead and create the unofficial mark scheme, just post the answers and the most agreed ones shall be updated for it.

    Please Correct any wrong answers and good luck with the rest of your exams.

    If anyone can remember the question numbers and which questions were under which number, that would be great thanks.
    --------------------------------------------

    Moles of reactants at eqbm 1.6 and 0.2 (2)
    Write a KC expression [G]^2/[E] x [F]^2 (1)
    Kc units mol^-1 dm^+3 (1)
    Kc value 0.30 (3)
    How does G conc change if vol increases, G decreases equ moves to left to raise pressure (3)
    T1 was higher than T2, exothermic eq to right to oppose temp decrease (3)
    What is weak acid slightly dissociated (1)
    PH of Caoh2 12.38 (3 or 4)
    Mass of carboxy salt 1.09g (5)
    pH acid 3.06 (3)
    Ka expression (1)
    equation of carboxylic acid with Na2CO3 gives salt, water and CO2 (1)
    CO2 in air (1) Aqueous CO2 is acidic, H+ react with OH-, less OH-. (3)
    Order A 2, Order B 0 (2)
    k constant is 5.05 (3)
    new rate 8.3x10^-6 (1)

    Nucleophillic addition
    Mechanism: CN- , lone pair arrow to carbon, one bond from C=O dissociates to C-O- with a lone pair, positive hydrogen, arrow from O lone pair to hydrogen.
    Distinguish enantiomers: Each rotates a plane of polarised light, one shall do so clockwise, the other anti clockwise, they rotate in opposite directions.
    Why is reaction slow with HCN? Low Ka, low amount of dissociation, so low amount of CN- available to react.


    IM force in kevlr is h bond (1)
    NH3 lone pair repelled by benzene ring (2)
    Mech is electrophilic sub with con hno3 and h2so4 reacting to make NO2+ (6) Sn and HCl reducing NO2 (1)

    nucl add elim with OH attacking cocl carbon a was 20-50ppm and carbon b was 60-90ppm (7)
    repeating unit of this was straight chain polyester ? (1)
    it was condensation polymer (1)
    use Br2/bromine water, benzene no reaction decolourises (Red-Brown to Colourless) with cyclohexene (3)
    ester 1 was the spectrum, 4.1ppm was ch2 with 3 h on adjacent c, next to O-C=O so shifted downfield, other quartet had 2.1-2.6ppm (4)
    quaternary ammonium (bromide) salt, nucl sub with CH3Br in excess (4)
    use tollens, nothing with J, K silver mirror, J has 2 peaks K has 4 (5)

    Final Question: Isomers of C5H8O2
    L. Methyl 2-methylpentanoate
    M. Carboxylic acid that is branched that shows no optical activity
    N. Carboxylic acid that shows optical activity
    O. (Can't remember this one)
    P. Cyclic structure that has one ketone group and has 2 peaks in its 1H n.m.r.: The structure was 5 carbons and an oxygen forming a cyclic ring, and the C=O group being on the carbon opposite the O.
    For nucleophilic addition elimination it's 20-50 and 50-90ppm

    You got the 20-50 right but for the second one you put 60 instead of 50.
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    (Original post by mynameisntbobk)
    Change in volume = change in conc = change in rate
    even so, the value of k only varies with temp
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    (Original post by faddys123)
    new rate 8.3x10^-6 (1) why was it this? Changing the volume changes the pressure therefore doesn't effect k? So i put down the same answer 5.05. Doesn't only temp effect value of k
    It shall not affect the K, but it does affect the concentrations of the species involved. All concentrations are divided by 2 due to the doubling, which altogether ended up being divide the entire thing by 8
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    (Original post by faddys123)
    even so, the value of k only varies with temp
    The question wasn't about k. It was about the new rate
 
 
 
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