Turn on thread page Beta
    Offline

    0
    ReputationRep:
    (Original post by apo1324)
    Has the mark scheme for the jan 2011 paper been posted by any chance? :P
    yes, check the first page of this thread
    Offline

    8
    ReputationRep:
    People, how do you rearrange a born haber cycle to find something other than lattice enthalpy? just had a mind block and the book doesn't make sense to me..
    Offline

    0
    ReputationRep:
    just did the 2011 jan paper and got 78 but the only reason i am happy is BECAUSE I FINALLY KNOW HOW TO DO REDOX EQUATIONS
    HIP HIP HURAY!!!!

    i am however gonna "ignore" any questions on enthalpy of solution/hydration .... dont get it!

    good luck everyone!!
    lool imagine if we get another hair perm style question. haha fingers crossed its a lovely paper!!!!!
    Offline

    2
    ReputationRep:
    (Original post by goldlock)
    The rate equation gives you the reactants and the molar quantities (look at the power of each reactant concentrations) involved in one step (the rate - determining step) of the reaction. I don't think there's any specific rule that it has to be the first step but I think it's decent practice to put it down as the first.
    Okay. But is it like the product/s of the 1st step are the reactants in the second step which react to form the overall product of the reaction? I'm confused
    Offline

    0
    ReputationRep:
    (Original post by entertheOJI)
    [[Fe(H20)6]2+] over [Fe2+]

    sorry, I don't know why I included H20 the first time. sorry for any confusion caused.
    Would you not include the H20 because it's a reactant? I thought you would only disregard it if it is generated as a product as it is in great excess anyway.
    Offline

    0
    ReputationRep:
    1) buffer systems --- HOW TO REMEMBER AND ANSWER TO GET MAXIMUM MARKS ?

    2) IN MANUFACTURE OF CaC2 what is the maximum mass of CaC2 that can be obtained from 40.0kg of Ca0 and 4kg of CO?

    CaO+ 3C------> CaC2 + CO
    Offline

    1
    ReputationRep:
    (Original post by 786girl)
    just did the 2011 jan paper and got 78 but the only reason i am happy is BECAUSE I FINALLY KNOW HOW TO DO REDOX EQUATIONS
    HIP HIP HURAY!!!!

    i am however gonna "ignore" any questions on enthalpy of solution/hydration .... dont get it!

    good luck everyone!!
    lool imagine if we get another hair perm style question. haha fingers crossed its a lovely paper!!!!!
    I'm on question 5 c) at the moment about carrying out the experiment etcetc
    The hairspray question blew my mind not a clue on that!!
    Offline

    8
    ReputationRep:
    (Original post by Student21)
    Okay. But is it like the product/s of the 1st step are the reactants in the second step which react to form the overall product of the reaction? I'm confused
    No denying this topic's a bit awkward - you need to write out the reactants of the first step from the rate equation, then below that, leave space for the second step and write the overall equation - you have to do a bit of detective work to fit that stuff together, the products of step 1 aren't always the reactants for step 2
    Offline

    0
    ReputationRep:
    (Original post by goldlock)
    I'd begin by writing down all of the reactants/products that you're given in the question, aside from any hydroxide ions, protons or H20 that you may well need to even things up - so, begin with saying that N02 + I- goes to I2 + NO
    Then, you need to work out which of these atoms change oxidation number, and balance those atmos that do (so, I goes from -1 to 0 so balance the number of iodines). That should set you on your way
    so would the answer be ...:

    H20 +I2 + NO2 - -----> NO + 2I- + 2OH-
    Offline

    11
    ReputationRep:
    Going to fail this badly :/
    Offline

    8
    ReputationRep:
    (Original post by bambinooo)
    so would the answer be ...:

    H20 +I2 + NO2 - -----> NO + 2I- + 2OH-
    Afraid not the atoms balance but the charges don't - look more closely at how N changes its oxidation number
    Offline

    0
    ReputationRep:
    any main things to keep in mind on buffer questions?
    Offline

    2
    ReputationRep:
    Could somone explain to me 4bii in the jan 2011 paper please. :L
    Offline

    8
    ReputationRep:
    (Original post by grainyshadeofgrey)
    any main things to keep in mind on buffer questions?
    I reckon a question'll come up that asks for the pH of a buffer, the main thing to bear in mind being that the concentration of the base doesn't equal the conc. of H+, the carbonic acid hydrogencarbonate stuff too, that'll probably show.
    Offline

    3
    ReputationRep:
    (Original post by susan23)
    exo is making bonds -Ve
    endo is breaking bonds +Ve

    ex-girlfriend makes *****es negative
    enormous butt is breaking positive

    LOL thats soooo crap....ahhahahahahaah
    so sorry about that they dont even make sense
    Hahahah
    Its difficult to remember your codes!

    I remember one in BIo
    King philip came over for great sex!


    Just realised this is the last paper and perhaps synoptic but havent seen any synoptic question so far!!!!!!:eek:
    Offline

    0
    ReputationRep:
    (Original post by grainyshadeofgrey)
    any main things to keep in mind on buffer questions?
    - Made from weak acid and salt of a weak acid.

    - Uses equilibrium (HA ---> H^+ + A^-) to minimise pH changes

    - When H^+ is added to the buffer solution it reacts with the conjugate base A^- and the position of equilibrium shifts to the left removing the added H^+ ions.

    - When OH^- is added to the buffer solution it reacts with a small concentration of H^+ ions (H^+ + OH^- ---> H2O). HA (weak acid) dissociates and the equilibrium shifts to the right restoring the H^+ ions that reacted.

    ^ That's the most important stuff.
    Offline

    0
    ReputationRep:
    (Original post by goldlock)
    afraid not the atoms balance but the charges don't - look more closely at how n changes its oxidation number
    does n go from 3+ to 2+??
    Offline

    8
    ReputationRep:
    (Original post by bambinooo)
    does n go from 3+ to 2+??
    It does, so you can use that to think about the overall change in oxidation/reduction
    Offline

    0
    ReputationRep:
    (Original post by hiyarearl)
    - made from weak acid and salt of a weak acid.

    - uses equilibrium (ha ---> h^+ + a^-) to minimise ph changes

    - when h^+ is added to the buffer solution it reacts with the conjugate base a^- and the position of equilibrium shifts to the left removing the added h^+ ions.

    - when oh^- is added to the buffer solution it reacts with a small concentration of h^+ ions (h^+ + oh^- ---> h2o). Ha (weak acid) dissociates and the equilibrium shifts to the right restoring the h^+ ions that reacted.

    ^ that's the most important stuff.
    thank you
    Offline

    0
    ReputationRep:
    I feel like crying. I just got 55 out of 100 on the June 2010 paper! Can someone please tell me what grade it is according to the grade boundaries for this paper? I can't find it anywhere! Please quote me! Thanks!
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: December 10, 2012

University open days

  • Heriot-Watt University
    School of Textiles and Design Undergraduate
    Fri, 16 Nov '18
  • University of Roehampton
    All departments Undergraduate
    Sat, 17 Nov '18
  • Edge Hill University
    Faculty of Health and Social Care Undergraduate
    Sat, 17 Nov '18
Poll
Black Friday: Yay or Nay?

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.