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    Anyone doing Unit 4 or 5 on wednesday?
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    yes, i am both got a B in un4 and in unit5 , what will come up ?
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    Just unit 5 for me.. I hate the fact that it is synoptic too.. =/
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    Yeah i'm doing both urgh its so close. I got 59/90 in unit 5 and 65/90 in unit 4 last time
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    What do you guys think will come up
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    recrystallization
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    what did you all think? I thought unit 4 was harder than unit 5. But the question about vanadium was hard, i couldn't fully do the calculation that was solid
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    (Original post by The Toffy)
    what did you all think? I thought unit 4 was harder than unit 5. But the question about vanadium was hard, i couldn't fully do the calculation that was solid
    We're not allowed to talk about it yet! =P
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    (Original post by munim)
    We're not allowed to talk about it yet! =P
    Oh poop.

    When?
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    (Original post by The Toffy)
    Oh poop.

    When?

    20mins. (Midnight) Lol!
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    Argh! I hated Unit 5 (again). That whole question on Vanadium was just so annoying! I couldn't do the calculations! 6 marks gone there.. =[ And then for the last mark, I justwrote the activation energy wasn't high enough.. For the reaction of vanadium with the H2SO4 (I think), I just put down +3. I don't think I will get any marks as it will probably be consequential on the working out or something. I don’t even know if it is right or not.

    Also, for the Ecell values, what did you guys do? I think I did it wrong now.. Did you compare it with Zn/Zn2+ each time? I didn’t.. I just did the Ecell of the VO2+ and the Zn one. Then I used the value I got for that to do the next one, and used that value to do the last where V2+ was made.. I think I got that completely wrong..

    For the recrystallisation question, what did you put down for the safety? I just said not next to naked flame because the solvent is flammable, so heat with water bath instead. Then I said to wear gloves, because azo dyes stain. I couldn’t think of anything..

    I was soo annoyed there weren’t any easy questions like write the electronic configuration of blah blah or anything like that. I expected there to be colour changes and ligand stuff! THERE WAS NONE! (If I remember correctly.. Lol!)

    For the chirality question, I wrote that the carbocation is planar, so it can be attacked from both sides (above or below), therefore making enantiomers of about 50:50 each. These rotate polarised light in different directions.

    I kept messing up my drawings too! Grrr!!! The SN1 and SN2 really started confusing me.. Oh and then what did people get for the answer to activation energy? I got 80.something kJmol-1. Yes? No?

    Erm.. I can’t remember many of the other questions.. Lol! Anyone remember?
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    (Original post by munim)
    Argh! I hated Unit 5 (again). That whole question on Vanadium was just so annoying! I couldn't do the calculations! 6 marks gone there.. =[ And then for the last mark, I justwrote the activation energy wasn't high enough.. For the reaction of vanadium with the H2SO4 (I think), I just put down +3. I don't think I will get any marks as it will probably be consequential on the working out or something. I don’t even know if it is right or not.

    Also, for the Ecell values, what did you guys do? I think I did it wrong now.. Did you compare it with Zn/Zn2+ each time? I didn’t.. I just did the Ecell of the VO2+ and the Zn one. Then I used the value I got for that to do the next one, and used that value to do the last where V2+ was made.. I think I got that completely wrong..

    For the recrystallisation question, what did you put down for the safety? I just said not next to naked flame because the solvent is flammable, so heat with water bath instead. Then I said to wear gloves, because azo dyes stain. I couldn’t think of anything..

    I was soo annoyed there weren’t any easy questions like write the electronic configuration of blah blah or anything like that. I expected there to be colour changes and ligand stuff! THERE WAS NONE! (If I remember correctly.. Lol!)

    For the chirality question, I wrote that the carbocation is planar, so it can be attacked from both sides (above or below), therefore making enantiomers of about 50:50 each. These rotate polarised light in different directions.

    I kept messing up my drawings too! Grrr!!! The SN1 and SN2 really started confusing me.. Oh and then what did people get for the answer to activation energy? I got 80.something kJmol-1. Yes? No?

    Erm.. I can’t remember many of the other questions.. Lol! Anyone remember?
    Sorry to hear mate, the SN1/SN2 question was a gift, it was like 8 marks for drawing a tertiary haloalkane for SN1 and primay for SN2. The reaction of SN1 is the formation of a carbocation being attacked by the nucleophile and SN2 is the transition state complex. Also for the calculation you take the E values from the page before to get the mole ratios and then work out moles from the conc and volume, then it was just compare/divide because the MnO4^- was 5:1 per electron, I got V^3+ but not sure my method was entirely correct...

    It was a fairly difficult paper, such as the Arrehenius equation, I took e of both sides and got the exponential function = k (yes a bit mathsy but I hadn't ever seen this question before).

    Hmmm did you get s^-1 for the units of k ?
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    (Original post by xSkyFire)
    Sorry to hear mate, the SN1/SN2 question was a gift, it was like 8 marks for drawing a tertiary haloalkane for SN1 and primay for SN2. The reaction of SN1 is the formation of a carbocation being attacked by the nucleophile and SN2 is the transition state complex. Also for the calculation you take the E values from the page before to get the mole ratios and then work out moles from the conc and volume, then it was just compare/divide because the MnO4^- was 5:1 per electron, I got V^3+ but not sure my method was entirely correct...

    It was a fairly difficult paper, such as the Arrehenius equation, I took e of both sides and got the exponential function = k (yes a bit mathsy but I hadn't ever seen this question before).

    Hmmm did you get s^-1 for the units of k ?

    Lol! The SN1 and SN2 was really good.. My brain just went to mush.. But I did exactly what you just said! WOOT!

    The Ecell thing, I did the formulae.. and worked out the moles.. So hopefully I will get some marks. I couldn't do the rest though. Hahaha!

    And yup. I got k=s-1! =D
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    wt do u think the grade boundaries would b for both unit 4 n5?
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    (Original post by munim)
    Lol! The SN1 and SN2 was really good.. My brain just went to mush.. But I did exactly what you just said! WOOT!

    The Ecell thing, I did the formulae.. and worked out the moles.. So hopefully I will get some marks. I couldn't do the rest though. Hahaha!

    And yup. I got k=s-1! =D
    Recrystallisation, it was 7 marks, I suspect it would be something like
    1 mark - Using water bath
    1 mark- Minimum hot solvent
    1 mark- filter in heated funnel
    1 mark- Cool and leave to recrystallise then filter under suction
    1 mark- wash with cold solvent and leave to dry
    1 mark- explain why the dye has to be more soluble/insoluble than impurity?
    1 mark - QWC?

    Not entirely sure but that would be my guess lol

    For the graph I got something like 75KJ mol^-1, I took the gradient of the first 2 values lol
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    (Original post by man u)
    wt do u think the grade boundaries would b for both unit 4 n5?
    I'd say.. 55/75 for an A in unit 4 and 53/75 for an A in unit 5 :p:
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    (Original post by xSkyFire)
    Recrystallisation, it was 7 marks, I suspect it would be something like
    1 mark - Using water bath
    1 mark- Minimum hot solvent
    1 mark- filter in heated funnel
    1 mark- Cool and leave to recrystallise then filter under suction
    1 mark- wash with cold solvent and leave to dry
    1 mark- explain why the dye has to be more soluble/insoluble than impurity?
    1 mark - QWC?

    Not entirely sure but that would be my guess lol

    For the graph I got something like 75KJ mol^-1, I took the gradient of the first 2 values lol
    I think you're right about the marking thing.. Although, Edexcel have never really given proper QWC marks.. Hahaha! The question is out of 7 and they have 7 points to make, me thinks..

    I used the gradient of the whole line! =s
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    wt was the answer to q1 prt b for unit 4
    mgcl2 and nacl2 qs
    i wrote that mg has higher chrge n sodium has lower chrge
    sodium ion does not hve high enough LE
    i wrte something like this
    will i only get 1 mrk?
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    (Original post by man u)
    wt was the answer to q1 prt b for unit 4
    mgcl2 and nacl2 qs
    i wrote that mg has higher chrge n sodium has lower chrge
    sodium ion does not hve high enough LE
    i wrte something like this
    will i only get 1 mrk?
    Why does MgCl2 exist but NaCl2 doesn't explain in terms of the energy changes?

    Sodium has one electron in the outer shell so the 1st IE can occur, but the second IE would need to remove an electron from an inner shell from an already Na+ ion, so this would require alot of energy, and so would not happen. MgCl2 can form it because it has 2 electrons in its outer shell.

    I had no idea it was a guess lol
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    wt abot y does co2 hve molecular shape rather than giant covalent
    is it because a lot of eneergy is needed to break the co2
 
 
 
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