Join TSR now and get all your revision questions answeredSign up now
    Offline

    0
    ReputationRep:
    Can anyone explain how the equation in question 3 (c) has been rearranged to find T.... it's been a while since I've done proper maths!! Name:  ImageUploadedByStudent Room1371579202.703766.jpg
Views: 146
Size:  82.3 KB


    Posted from TSR Mobile
    Offline

    0
    ReputationRep:
    MgO how is it sparingly soluble in water? surely it forms Mg(OH)2
    June 2012
    Offline

    1
    ReputationRep:
    (Original post by xodani)
    Can anyone help with June 2011 3ai) Why is the answer -38 and not -76?
    It says formation of one mole of NH3 not 2.
    Offline

    1
    ReputationRep:
    (Original post by Ren_9)
    Can anyone explain how the equation in question 3 (c) has been rearranged to find T.... it's been a while since I've done proper maths!! Name:  ImageUploadedByStudent Room1371579202.703766.jpg
Views: 146
Size:  82.3 KB


    Posted from TSR Mobile
    They've just collected the terms with T on one side and the terms with no T on the other.
    Offline

    0
    ReputationRep:
    (Original post by xodani)
    Can anyone help with June 2011 3ai) Why is the answer -38 and not -76?
    You have to calculate it per mol. Just divide your answer by 2 since two mols of ammonia is produced


    Posted from TSR Mobile
    Offline

    0
    ReputationRep:
    (Original post by jqian)
    It says formation of one mole of NH3 not 2.
    Ah how silly of me! Thank you very much
    Offline

    3
    ReputationRep:
    can some one please tell me whether to use (products - reactants) and (reactants - products) when calculating enthalpy change. Thanks in advance.
    Offline

    0
    ReputationRep:
    (Original post by jqian)
    They've just collected the terms with T on one side and the terms with no T on the other.
    I don't mean to be annoying but if you take T to the other side wouldn't it just cancell out (Eg -T+T=0 ) ?? *confused*


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by tilownii)
    Why does it say purple or yellow in January 2013
    oh crap, my mistake. [Fe(H2O)6]3+ IS yellow, just all the complexes it makes are brown
    Offline

    1
    ReputationRep:
    (Original post by darryalar)
    can some one please tell me whether to use (products - reactants) and (reactants - products) when calculating enthalpy change. Thanks in advance.
    If you're given enthalpy of combustion data, use reactants - products (use cr'a'p, combustion reactants- products).
    If you're given enthalpy of formation use products - reactants.
    If you're given the bond enthalpies then you use sum of the bonds broken (i.e. the reactants) - the sum of the bonds formed (the products).
    Offline

    9
    ReputationRep:
    Whew, done 7 past papers today (everything besides the specimen). This is like my third time going through them so I think I'm just about as ready as I'll ever be...

    Probably just going to go over random questions for the next couple of hours.

    How is everyone feeling about tomorrow?
    Offline

    0
    ReputationRep:
    Can anyone give me the equation for when H202 is used as an oxidising agent? Thanks
    Offline

    1
    ReputationRep:
    (Original post by Ren_9)
    I don't mean to be annoying but if you take T to the other side wouldn't it just cancell out (Eg -T+T=0 ) ?? *confused*


    Posted from TSR Mobile
    On the left hand side you have -542.6T, on the right hand side you have -15.2T, if you add 542.6T to both sides the left hand side now has no T terms as -542.6T + 542.6T = 0T = 0. The right hand side becomes -15.2T + 542.6T which is 527.4T.
    Offline

    1
    ReputationRep:
    (Original post by JamilMCR)
    Can anyone give me the equation for when H202 is used as an oxidising agent? Thanks
    H2O2 + 2e- --> 2OH-
    Offline

    0
    ReputationRep:
    (Original post by examgirl)
    How do you balance/write an equation for pottasium manganate and hydrogen peroxide. Please help x
    Someone please xx
    Offline

    3
    ReputationRep:
    (Original post by jqian)
    If you're given enthalpy of combustion data, use reactants - products (use cr'a'p, combustion reactants- products).
    If you're given enthalpy of formation use products - reactants.
    If you're given the bond enthalpies then you use sum of the bonds broken (i.e. the reactants) - the sum of the bonds formed (the products).
    Just what i wanted, many thanks.
    Offline

    0
    ReputationRep:
    Guys has anyone got the jan13 paper and mark scheme?

    thanks
    Offline

    0
    ReputationRep:
    (Original post by jon510)
    Guys has anyone got the jan13 paper and mark scheme?

    thanks
    someone previously posted it, here you go:http://www.thestudentroom.co.uk/show...2#post42254412
    Offline

    0
    ReputationRep:
    (Original post by darryalar)
    can some one please tell me whether to use (products - reactants) and (reactants - products) when calculating enthalpy change. Thanks in advance.

    For enthalpy change: reactants - products

    for enthalpy of formation: products - reactants
    for entropy change: products - reactants
    Offline

    0
    ReputationRep:
    Can someone please explain to me when to put Pt on cell representations
 
 
 
Poll
Should MenACWY vaccination be compulsory at uni?

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.