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

Edexcel A2 Chemistry Exams -6CH04 (14th June) and 6CH05 (22nd June) Discussion Thread Watch

    Offline

    2
    ReputationRep:
    Name:  image.jpg
Views: 147
Size:  507.1 KB Can someone explain to me why the answer can't be D? I've eliminated A and B. But I was thinking since Conc HCl would shift the equilibrium of the second equation to the right hence making the Ecell of the reaction more positive. Since Ecell, Stotal and K are all proportional I thought D would make sense...
    Thank you!
    Offline

    6
    ReputationRep:
    (Original post by MacroniCheese)
    Name:  image.jpg
Views: 147
Size:  507.1 KB Can someone explain to me why the answer can't be D? I've eliminated A and B. But I was thinking since Conc HCl would shift the equilibrium of the second equation to the right hence making the Ecell of the reaction more positive. Since Ecell, Stotal and K are all proportional I thought D would make sense...
    Thank you!
    Remember unit 4 equilibria that the only way you can alter Kc is by changing the temperature
    Offline

    2
    ReputationRep:
    (Original post by Whizbox)
    Remember unit 4 equilibria that the only way you can alter Kc is by changing the temperature
    Oh my god...I'm a complete idiot.. 😅. Thanks haha I think I've basically tried to throw unit 4 out of my head
    Offline

    2
    ReputationRep:
    Okay so elaborating on that, When does Ecell affect K? I'm getting really confused, I've got it written down that the more positive the value of Ecell the larger the value of the equilibrium constant. Does that only matter if temperature makes the Ecell more positive? But I know pressure and concentrations can also make Ecell more positive!
    Sorry I'm probably overlooking something really simple here
    • Thread Starter
    Offline

    10
    ReputationRep:
    (Original post by Ayman!)
    There was a dibasic titration curve on ours along with sketching an NMR and designing a rate experiment involving the Arrhenius equation worth a tonne of marks. I have the general ideas on all of those correct but since they haven't be tested before, I have no idea how much I'll lose on each. I might lose 1-2 on the titration curve because my volume axis stuff probably wasn't very accurate and 1 on the NMR because of the height of my peaks. Losing a couple of marks here and there, I'm predicting myself a 75 (might be a little generous ). Wasn't too bad in my opinion, but definitely a little challenging - I enjoyed it though haha

    I'll be bothering you with a few U5 questions later on if you don't mind. I'm currently doing the 2013 paper.
    Did the 2013 paper earlier, was interesting but ngl i was winging it a bit at some points given it was my first unit 5 paper in ages. Was quite surprised how high the ums was tbh
    Offline

    2
    ReputationRep:
    How many Unit 5 past papers do people have left now? Any particularly hard past papers that you've come across that i could try?
    Offline

    3
    ReputationRep:
    (Original post by ayvaak)
    How many Unit 5 past papers do people have left now?
    6, but I only plan on doing 4 as I won't be doing the UK papers.

    (Original post by ayvaak)
    Any particularly hard past papers that you've come across that i could try?
    All of them. :cry:

    (Original post by samb1234)
    Did the 2013 paper earlier, was interesting but ngl i was winging it a bit at some points given it was my first unit 5 paper in ages. Was quite surprised how high the ums was tbh
    Same. I was pretty surprised at the boundaries. I did Jan 2014 recently as well and ended up getting a high B. Thought certain parts were nasty but boundaries suggest otherwise. Haha, Unit 5 will not end well for me. :rofl:
    • Thread Starter
    Offline

    10
    ReputationRep:
    (Original post by Ayman!)
    6, but I only plan on doing 4 as I won't be doing the UK papers.



    All of them. :cry:



    Same. I was pretty surprised at the boundaries. I did Jan 2014 recently as well and ended up getting a high B. Thought certain parts were nasty but boundaries suggest otherwise. Haha, Unit 5 will not end well for me. :rofl:
    Haha yeah the papers are much worse for unit 5. Were there any questions you had from that 2013 one btw?
    Offline

    3
    ReputationRep:
    (Original post by samb1234)
    Haha yeah the papers are much worse for unit 5. Were there any questions you had from that 2013 one btw?
    A couple of the MCQs - 6 and 13.
    • Thread Starter
    Offline

    10
    ReputationRep:
    (Original post by Ayman!)
    A couple of the MCQs - 6 and 13.
    the june uk one right?
    Offline

    3
    ReputationRep:
    (Original post by samb1234)
    the june uk one right?
    Yep, not the R paper. I forgot exactly what these questions were, but I wrote them down on a chit
    Offline

    2
    ReputationRep:
    (Original post by MacroniCheese)
    Okay so elaborating on that, When does Ecell affect K? I'm getting really confused, I've got it written down that the more positive the value of Ecell the larger the value of the equilibrium constant. Does that only matter if temperature makes the Ecell more positive? But I know pressure and concentrations can also make Ecell more positive!
    Sorry I'm probably overlooking something really simple here
    Hey temperature is not the only thing that affects E cell
    If equilibrium shifts to the left, E cell is lowered
    if equilibrium shifts to the right, E cell increases
    This is probably what you mean by things like pressure shifting the POSITION of equilibrium

    george Facer textbook says "the actual relationship is complex and need not be learnt" so just remember that a positive E cell = positive delta S total = larger K constant.
    Offline

    2
    ReputationRep:
    15 cm3 of a gaseous hydrocarbon requires 90 cm3 of oxygen for completecombustion, both volumes being measured at 15􀁱C and 1 atm. The formula of thehydrocarbon is

    A C4H6
    B C4H8
    C C4H10
    D impossible to calculate without knowing the molar volume of gases underthese conditions.

    Guys how do you do this? Please help
    • Thread Starter
    Offline

    10
    ReputationRep:
    (Original post by Ayman!)
    Yep, not the R paper. I forgot exactly what these questions were, but I wrote them down on a chit
    Idk how chemically correct it is, but my logic for 6 was that the more positively charged the overall complex is the more readily it will undergo deprotonation so it's c. 13 is B, we know from base hydrolysis we are going to get the salt which gives us A,B or d. If it's in alkali it's not going to be the one with NH3+ as that would just protonate an OH, and A doesn't have the groups in the right place
    Offline

    2
    ReputationRep:
    I did the June 2013 (R) unit 5 today...fun tiems
    Offline

    2
    ReputationRep:
    (Original post by Don Pedro K.)
    I did the June 2013 (R) unit 5 today...fun tiems
    Same! Though I only finished the MCQ then started section B...the fuel cells question made me lose all my morale 😓 So I stopped :/
    Offline

    2
    ReputationRep:
    (Original post by MacroniCheese)
    Same! Though I only finished the MCQ then started section B...the fuel cells question made me lose all my morale 😓 So I stopped :/
    I'm marking section C right now XD Btw, if you wrote a correct answer and something else after that but didn't cross anything out, would you still get marks for the correct bits :s?
    Offline

    2
    ReputationRep:
    (Original post by Don Pedro K.)
    I'm marking section C right now XD Btw, if you wrote a correct answer and something else after that but didn't cross anything out, would you still get marks for the correct bits :s?
    I think that's where the harshness of the examiners comes in tbh. As long as none of your answer is the reject column I think it should be fine as long as it doesn't contradict
    Offline

    2
    ReputationRep:
    (Original post by MacroniCheese)
    I think that's where the harshness of the examiners comes in tbh. As long as none of your answer is the reject column I think it should be fine as long as it doesn't contradict
    Ah okay, awesome! I'll just remember to cross any other stuff out next time.. XD I finished marking it and got 71/90. I guess that's not too bad I was expecting a lot worse whilst doing the paper lol! The mistakes I made were mostly wording stuff incorrectly, so I just need to brush up on my answering technique ahha :s! Let me check the grade boundaries real quick...

    Wow!! 111 UMS !!! I was NOT expecting that XD wow I'm actually really happy now haha!
    Offline

    2
    ReputationRep:
    (Original post by Don Pedro K.)
    Ah okay, awesome! I'll just remember to cross any other stuff out next time.. XD I finished marking it and got 71/90. I guess that's not too bad I was expecting a lot worse whilst doing the paper lol! The mistakes I made were mostly wording stuff incorrectly, so I just need to brush up on my answering technique ahha :s! Let me check the grade boundaries real quick...

    Wow!! 111 UMS !!! I was NOT expecting that XD wow I'm actually really happy now haha!
    Good stuff! You should be good to go by next Wednesday
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Has a teacher ever helped you cheat?
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • 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.