Turn on thread page Beta
    Offline

    3
    ReputationRep:
    I'm gonna go over random bits of revision guys:

    Cr2+ can be [O] to Cr3+ by reducing Cr2O7^2- by zinc in acid sol.
    H2 can be used to exclude air
    Then the equations:
    Cr2O7^2- is [R] to Cr3+
    Zn is [O] to Zn2+

    I heard the unit 4 June paper was tough so bit worried about this one, very worried. :cry2:
    Offline

    0
    ReputationRep:
    (Original post by Sparkly-Star)
    Me too!

    Ugh, the annoying thing is I should've gotten an A in unit 4 but I completely blanked out there was so much to learn and this was my last exam in Jan by then I had forgotten everything despite spending countless hours on it. -_- So I need to do extra well in this unit. :mad2:
    I have to say that I love this smilie :mad2: ... it sums up my ranting and raving about AQA every exam period, especially about shrew papers in Biology lol

    I'm reaching the end of my first chapter, so I'm making steady progress. I started with Chapter 16 first because its got so many equations and colours :sigh:

    Lets hope AQA are nice so that we can ace the exam but not too nice that the grade boundaries go up
    Offline

    3
    ReputationRep:
    (Original post by strawberry_cake)
    I hate it when that happens, especially if its easy marks, that really puts me off I just can't wait for tomorrow to be over, although I wouldn't have minded an extra day or two
    Give me another week haha.
    Offline

    0
    ReputationRep:
    so going to fail
    last exam so staying up all the way till the exam tomorrow !!!
    oh god please help me!!
    Offline

    0
    ReputationRep:
    Can someone please tell me 4a for feb2010 paper? I don't know how its 242? Thanks
    Offline

    3
    ReputationRep:
    (Original post by GoodOl'CharlieB)
    I have to say that I love this smilie :mad2: ... it sums up my ranting and raving about AQA every exam period, especially about shrew papers in Biology lol

    I'm reaching the end of my first chapter, so I'm making steady progress. I started with Chapter 16 first because its got so many equations and colours :sigh:

    Lets hope AQA are nice so that we can ace the exam but not too nice that the grade boundaries go up
    Me too :love: I started with 15 for the same reason, I find 16 easier. Luckily I had to do tons of revision on chapter 15/16 for my ISA so I don't find them too bad.
    Yeah I don't think the difficulty will change a lot, the grade boundaries seem to stay around the same numbers. :yep:
    Hmm on another note, where are all the chem people? The bio thread was full!
    Offline

    0
    ReputationRep:
    (Original post by strawberry_cake)
    I hate it when that happens, especially if its easy marks, that really puts me off I just can't wait for tomorrow to be over, although I wouldn't have minded an extra day or two
    What is keeping me revising is thought of freedom at 10:45 tomorrow, as soon as I hand in that paper its going to be one big party :party:

    I just keep thinking of all the fun things I've planned this summer and about getting into uni...otherwise I probably would have gone insane :crazy:

    We can do this!!
    Offline

    0
    ReputationRep:
    (Original post by ceeebs)
    got about 3 left coz bio revision came in the way
    woow! thats hard core revision, am on 2006 now hope to finish by this afternoon the rest.
    Offline

    3
    ReputationRep:
    (Original post by strawberry_cake)
    Can someone please tell me 4a for feb2010 paper? I don't know how its 242? Thanks
    Cos it's twice the atomization of the first one in the table from the top of my head. :yep:
    Offline

    0
    ReputationRep:
    (Original post by Sparkly-Star)
    Cos it's twice the atomization of the first one in the table from the top of my head. :yep:
    Ohh but then for 4dii) why don't we double the values for Cl? And thanks
    Offline

    3
    ReputationRep:
    Almost done with chapter 15. :jive: Longest chapter of all damn it. :p:
    Offline

    3
    ReputationRep:
    (Original post by strawberry_cake)
    Ohh but then for 4dii) why don't we double the values for Cl? And thanks
    Cos we're forming AgCl which contains only 1 Cl-
    Offline

    15
    ReputationRep:
    Do anyone feel like they don't have enough time I'm so screwed for tomorrow!
    Offline

    0
    ReputationRep:
    Help me!!! I am confused about lattice enthalpy. Is -1025KJ/mol greater or lesser than -998KJ/mol. Mathematically, -1025 is lesser, but I don't know why me book is confusing me. Could you also explain the trend in lattice enthalpy of formation (based on ion size and charge) and electron affinity down the group?
    Offline

    10
    ReputationRep:
    Am I the only person who doesn't have study leave?
    I've got to go into college still today!

    Good luck for tomorrow everyone!

    What is everyone learning for the synoptic stuff?
    I dont have any of the previous books because we have to hand them in
    Anyone want to give me a quick overview? Would be amazing haha

    Thanks!
    Offline

    3
    ReputationRep:
    Has everyone memorized 15.4/15.5?
    Offline

    10
    ReputationRep:
    (Original post by Crowned Temmy)
    Help me!!! I am confused about lattice enthalpy. Is -1025KJ/mol greater or lesser than -998KJ/mol. Mathematically, -1025 is lesser, but I don't know why me book is confusing me. Could you also explain the trend in lattice enthalpy of formation (based on ion size and charge) and electron affinity down the group?
    Probably easier if you say it is more negative. So more energy is needed to break the bonds within the lattice.

    Across the period, ion size decreases because nuclear charge increases, and attracts the electrons more, so atomic radius decreases. This means that there is a higher charge:size ratio, so attracts the other ions in the ionic lattice more. Al2O3 also has a degree of covalent bonding, so its experimental value will be higher than that calculated in the perfect ionic model.

    But SiO2 makes a macromolecular lattice, held by covalent bonding, so lots of energy needed to break strong covalent bonds.

    P4O10 onwards, simple molecular structures, so weak intermolecular forces.

    The lattice formation is just the -ve of the lattice dissociation, so you can use that to find the trend

    Not sure about electron affinity down the group though, sorry!
    Offline

    3
    ReputationRep:
    (Original post by Crowned Temmy)
    Help me!!! I am confused about lattice enthalpy. Is -1025KJ/mol greater or lesser than -998KJ/mol. Mathematically, -1025 is lesser, but I don't know why me book is confusing me. Could you also explain the trend in lattice enthalpy of formation (based on ion size and charge) and electron affinity down the group?
    From the top of my head, it is less mathematically BUT think of it as fireworks which is exo. If you had fireworks and had one of them sparkly things it might be -998 which is small but if you had one of those big fireworks in the air (whatever they're called ) those are greater -1025 hence it is MORE exo.

    Lattice enthalpy increases as the size of the ions decreases this is because the ions are more attracted I think.

    Electron affinity, not sure.
    Offline

    0
    ReputationRep:
    hi, can someone please help me with thermodynamics... it will help you revise too
    i understand the terms and stuff but it's not too clear.. any help on the wholeeeeeeee topic will be sooooo much appreciated .. thanks
    Offline

    3
    ReputationRep:
    (Original post by Luke0011)
    Am I the only person who doesn't have study leave?
    I've got to go into college still today!

    Good luck for tomorrow everyone!

    What is everyone learning for the synoptic stuff?
    I dont have any of the previous books because we have to hand them in
    Anyone want to give me a quick overview? Would be amazing haha

    Thanks!
    I doubt anything from unit 4 will come up maybe bits and bobs from unit 1/2 so things like percentage yield and so on, energetics, extraction of metals maybe.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: August 20, 2011
Poll
Cats or dogs?

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.