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

    1
    ReputationRep:
    (Original post by lahigueraxxx)
    Completely ****ed up the born haber cycle, honestly no idea how or why I got +1910 or something Stupid mistakes
    i got that too
    Are you sure its wrong?
    Offline

    8
    ReputationRep:
    (Original post by lahigueraxxx)
    Completely ****ed up the born haber cycle, honestly no idea how or why I got +1910 or something Stupid mistakes
    I got the same as you originally but when I went back, I forgot to multiply the ionisation Enthalpy by 2 and that's how I got 2000 something so I'm sure you didn't multiply it by 2
    Offline

    7
    ReputationRep:
    did anyone get +2404 or something for born haber?
    Offline

    1
    ReputationRep:
    What did everyone get for delta G
    Offline

    1
    ReputationRep:
    (Original post by vinchy)
    Purity 50.7 anyone?
    Yes i got around that! I think quite of few have
    Offline

    6
    ReputationRep:
    (Original post by GiveShekels)
    i got that too
    Are you sure its wrong?
    I got it too :/
    Offline

    11
    ReputationRep:
    (Original post by Suits101)
    It wanted standard enthalpy change, hence you do it for one mole hence you divide answers by 2 I believe (that's what happened on a previous mark scheme)
    I'm pretty sure it just asked for the enthalpy change for the reaction, and they provided you with the standard enthalpy changes for 1 mole, so I think you had to multiply the values by 2 not divide by 2.
    Offline

    2
    ReputationRep:
    (Original post by emsieMC)
    I remember thinking that and was unsure about whether to divide, so I just left it undivided and did the calculation that way
    did it specify for the formation of one mole?
    Offline

    3
    ReputationRep:
    (Original post by Suits101)
    Hi I have some questions and answers if anyone wants to add to it?

    Lattice dissociation of K2O being less endothermic than Na2O:

    K+ ions are bigger than Na+ ions
    Weaker electrostatic force of attraction between K+ and O2- ions/weaker ionic bonding
    Less energy needed to break the ionic lattice

    Solubility of MgCl2 decreases
    Forward reaction is exothermic
    Equilibrium shifts left to oppose increase in temperature

    Enthalpy of solution = -155 kJ/mol
    Question stated that solubility is defined as the amount of solid able to dissolve in water, so as it is an endothermic reaction, more MgCl2 is produced if you increase temperature, hence solubility is increased
    Offline

    3
    ReputationRep:
    (Original post by Ejsjwwj)
    What did everyone get for delta G
    -135.0 KJ mol-1
    Offline

    5
    ReputationRep:
    (Original post by Suits101)
    Hi I have some questions and answers if anyone wants to add to it?

    Lattice dissociation of K2O being less endothermic than Na2O:

    K+ ions are bigger than Na+ ions
    Weaker electrostatic force of attraction between K+ and O2- ions/weaker ionic bonding
    Less energy needed to break the ionic lattice

    Solubility of MgCl2 decreases
    Forward reaction is exothermic
    Equilibrium shifts left to oppose increase in temperature

    Enthalpy of solution = -155 kJ/mol
    for the lattice dissociation question i put na+ ions were smaller and that there is a stronger attraction between the molecules, would i still get the marks???
    Offline

    2
    ReputationRep:
    Unofficial mark scheme?
    Offline

    0
    ReputationRep:
    **** was it 50 degrees celcius or kelvin for the enthalpy/entropy one?
    Offline

    1
    ReputationRep:
    (Original post by ManOfJustTin)
    Did anyone else pick sulphur for X?
    I'm such an idiot 😂😂😭

    Still such an easy paper I'm so happy
    You couldn't put sulphur is specifically said sodium to phosphorus only
    Offline

    2
    ReputationRep:
    (Original post by 09ekennedy)
    -135.0 KJ mol-1
    i got that
    Offline

    2
    ReputationRep:
    (Original post by rwehy)
    **** was it 50 degrees celcius or kelvin for the enthalpy/entropy one?
    50 degrees C
    Offline

    12
    ReputationRep:
    (Original post by ManOfJustTin)
    Did anyone else pick sulphur for X?
    I'm such an idiot 😂😂😭

    Still such an easy paper I'm so happy
    I did, then changed it last minute.

    (Original post by emsieMC)
    I think it was h2so4, that's what I put
    I put that too. Pretty sure thats whats written in the book
    (Original post by thehollowcrown)
    Does the pressure have an effect on the emf? I said the emf increases eqbrm shift blah blah, but wasn't sure on that
    Yeah I said it increased emf because position of eq shifts to side with less mols favoring reduction.


    Know I mucked up on the calc question, I couldn't do it Can't remember what I put for the solubility question, I know I wrote about equilibria but I'm scared I wrote solubility increases :/

    And the born haber wtf....May have messed up on that too.

    All in all, much better than unit 4.
    Offline

    16
    ReputationRep:
    (Original post by 09ekennedy)
    -135.0 KJ mol-1
    I got - 67.5 because I halved my values beforehand as 2 moles of product were being formed. Standard enthalpy of formation by definition is the formation of 1 mole of a compound.

    Posted from TSR Mobile
    Offline

    2
    (Original post by RefusedAccess)
    Question stated that solubility is defined as the amount of solid able to dissolve in water, so as it is an endothermic reaction, more MgCl2 is produced if you increase temperature, hence solubility is increased
    It said use your answer from the question above.

    The answer was negative, hence the forward reaction is exothermic.

    This same question (but with a different compound) came up in a previous paper.

    (Original post by Ejsjwwj)
    What did everyone get for delta G
    -65.1 (divide it by 2 because it's standard meaning one mole, not two as question gave)
    Offline

    1
    ReputationRep:
    (Original post by ManOfJustTin)
    Did anyone else pick sulphur for X?
    I'm such an idiot 😂😂😭

    Still such an easy paper I'm so happy
    I did!! You are not alone but it was only like 2 marks so don't worry about it if I were you!
 
 
 
Poll
Do you agree with the PM's proposal to cut tuition fees for some courses?

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

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