Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta
    Offline

    0
    ReputationRep:
    (Original post by lou12)
    yes i got all of those. execpt i forgot to put white solid for MgO dam. also did you put hydrogen fuel cell or standard hydrogen electrode for the emf one
    Hydrogen fuel cell, that whole last part of the question was a little hazy but i might have been able to blag a few marks
    Offline

    0
    ReputationRep:
    (Original post by Betsss)
    For the Cu with C2O42- complex, did people cut draw it with 2 lots of CrO42- and no water ligands? i think i saw on the question that you weren't supposed to draw the water ligands, but i cant remember now!
    Yeah said you don't need to show the water ligands
    Offline

    0
    ReputationRep:
    Aluminium Oxide testing? Molten Cryolite, Electrolysis??
    Offline

    0
    ReputationRep:
    For the first question, where you had to explain the interactions between Flouride ions and water, was it hydrogen bonding?
    Offline

    0
    ReputationRep:
    (Original post by jamest92)
    Hydrogen fuel cell, that whole last part of the question was a little hazy but i might have been able to blag a few marks
    cool, me too
    Offline

    0
    ReputationRep:
    (Original post by SnookerLoopy)
    what did people get as the percentage of iron? 8.74 or something ?
    I got around 50 %
    Offline

    0
    ReputationRep:
    (Original post by M | k e)
    Yes and in the CGP book it has the exact example but with their cell as 2.05V, and their answers -0.36. Ours was 2.15V so can be sure -0.46V is right
    Yay thanks! and the other one was +1.1?
    Offline

    1
    ReputationRep:
    (Original post by Betsss)
    For the first question, where you had to explain the interactions between Flouride ions and water, was it hydrogen bonding?
    ah yeah i didnt like that one, i put that water is polar so the polar hydrogon atoms in water have a slight positive charge and are attracted towards the fluoride ions and said something about forming like a sheath around it.. no idea if its right tho :/
    Offline

    1
    ReputationRep:
    For the ammonia question where we had to find the entropy, and many people forgot to divide by 2 (myself included), the question beforehand was the enthalpy change for the production of 1 mole of ammonia.

    Would we have to divide that by two, also? Seeing as the equation creates 2 moles of ammonia.

    Funny, I divided by two for the enthalpy, but not the entropy. How stupid of me.
    Offline

    0
    ReputationRep:
    Anyone get 53.7% for the iron one?
    Offline

    0
    ReputationRep:
    (Original post by Betsss)
    Yay thanks! and the other one was +1.1?
    S'what I got
    Offline

    0
    ReputationRep:
    (Original post by Van_der_Waals)
    Yeah, haha, an easy 6 marks (hopefully ). I don't see why they can't use consistent symbols throughout both physics and chemistry though, it's E=hf not \DeltaE=hv! :p:
    can you remember the ans to the first que in that page
    Offline

    0
    ReputationRep:
    (Original post by Betsss)
    Did people get -0.46 for the E value for the negative terminal?
    that value sounds familiar
    Offline

    0
    ReputationRep:
    (Original post by SnookerLoopy)
    what did people get as the percentage of iron? 8.74 or something ?
    I got something like that but I think people are saying something about a ratio of 1:6. I don't remember seeing that in the question. I probably neglected to read it properly.
    Offline

    0
    ReputationRep:
    (Original post by al_habib)
    can you remember the ans to the first que in that page
    Something about why is Copper(II) ions blue?

    I said the d subshell splits when ligands attach, forming levels of different energy. The electrons in it require energy = delta E to make the jump to higher energy level. They get this energy by absorbing light, in copper then absorb red light, and reflect the rest, because red is absorbed this mean blue gets reflected and is visible at this colour .

    Not 100% about my physicsy stuff but it's along those lines
    Offline

    0
    ReputationRep:
    (Original post by Betsss)
    Anyone get 53.7% for the iron one?
    Thank god, someone else
    Offline

    0
    ReputationRep:
    (Original post by Smartie77)
    I got something like that but I think people are saying something about a ratio of 1:6. I don't remember seeing that in the question. I probably neglected to read it properly.
    You had to work out the ratio yourself. Cr2O7 2- + 6Fe2+ you ended up with. So when you work moles of Cr2O7 2- from the data given, you just times by 6 for moles of iron. Then can use n=mass/Mr to find the mass of iron, and the %.

    I got like 53.7%
    Offline

    0
    ReputationRep:
    (Original post by Smartie77)
    I got something like that but I think people are saying something about a ratio of 1:6. I don't remember seeing that in the question. I probably neglected to read it properly.
    Oh right, I couldn't be bothered working out the ratio, I just said 'assuming it's a 1:1 reaction' ...We'll probably pick up about 3 marks for it though (out of 5)
    Offline

    1
    ReputationRep:
    (Original post by Smartie77)
    I got something like that but I think people are saying something about a ratio of 1:6. I don't remember seeing that in the question. I probably neglected to read it properly.
    Fe 2+ ---> Fe 3+ + e-

    Cr2O7 2- + 14H+ + 6e- ---> 2Cr 3+ + 7H2O

    THEREFORE: 6Fe 2+ + Cr2O7 2- + 14H+ ---> 2Cr 3+ + 6Fe 3+ + 7H2O


    That's how you get your ratio.
    Offline

    0
    ReputationRep:
    For why copper (II) ions are blue, i put:
    - Cu2+ is a transition metal ion, so it has an incomplete d-sublevel
    - it can undergo d-to-d transitions
    - the electrons absorb light, which excites them to a higher energy level
    - they then emit light to fall back to ground state
    - Cu2+ ions absorb red light from the visible spectrum; so they will appear the complementary colour (blue)

    Is this ok, this was the section i was least confident with and it had to come up!!
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: August 20, 2011
Poll
Do you agree with the proposed ban on plastic straws and cotton buds?

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.