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OCR A2 CHEMISTRY F324 and F325- 14th and 22nd June 2016- OFFICIAL THREAD

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Pretty sure the reagent was starch and the observation was blue/black to colourless. You can type it into YouTube and see the end point; and that's what happened

yeah ya dun dun, did this practical in school so was a bit surprised seeing people put other stuff

Reply 3501

mosheezie

Original post by swopnil

Yeah, agree it was quite easy but stop being obtuse! :smile:

Obtuse? Am i an angle fam? :colonhash:

Reply 3502

Cal 1

Original post by BioStudentx

I think it's -2? You're making me doubt myself now aha.

It was 2- don't worry😊
The ligand had a 2- charge and there were 2 of them bound to a Cu2+ ion

Reply 3503

BrownGuyIrfan

"you will never be asked to make multi-step reaction mechanisms that are more than two stages"

k den

Reply 3504

Beta14

It was -2 because the group that was attached to it was -2 and there was two of them so +2-4 = -2. Well thats what i did anyways

Original post by BioStudentx

I think it's -2? You're making me doubt myself now aha.

Reply 3505

k.russell

Original post by Brandoncarlin

I don't remember H+ being in the rate equation, only H2O2 and I-

You do need 2 I- there was 2 I- in the overall equation...

Reply 3506

Clankdroid

Original post by Brandoncarlin

I don't remember H+ being in the rate equation, only H2O2 and I-

sorry my bad, the other I- was in the given equation

Reply 3507

Cal 1

For the multi step reaction mechanism, did anyone else get 2 of the steps the same?

H^+ + OH^- ---> H2O

Spent about 5 minutes checking and everything cancelled to give the overall equation

Reply 3508

dairychocolate

Original post by BioStudentx

They gave entropy change and you had enthalpy change of solution. The entropy change was 0.22 something (I think)?

I got -43 roughly.

Yeah, I converted KJ to J and got -43000.

Reply 3509

d14m

So I thought I did okay in that exam up until reading through this thread :smile:

Reply 3510

Clankdroid

Original post by Brandoncarlin

Need 2I- on the left-hand side

The guy that wrote that accidentally put H+ instead of I- so both methods are correct

Reply 3511

nikm001

Original post by sophiewei

I put alkali. Because i worked out neutral ph as 6.5 so 7 is greater than 6.5 therefor alkali.

i did the same thing too. i think they should credit that responce

Reply 3512

cr7alwayz

Did the empirical formula ask for the charge as well?

Reply 3513

underestimate

What was the answer to the colour of the CuCl4 ligand as it wasnt mentioned that excess HCl was used?

Reply 3514

dairychocolate

Original post by cr7alwayz

Did the empirical formula ask for the charge as well?

Yeah, I think so. I think I put 2-.

Original post by underestimate

What was the answer to the colour of the CuCl4 ligand as it wasnt mentioned that excess HCl was used?

I thought it was just yellow.

Reply 3515

BioStudentx

Original post by BrownGuyIrfan

"you will never be asked to make multi-step reaction mechanisms that are more than two stages"

k den

Hahaha, that question took the piss! Does it actually say that? I mean tbf, you did only fill in 2 steps, the other 2 were given to you.

Reply 3516

Kinkychemist

Original post by k.russell

Agreed! Definitely not harder than last years and won't have higher UMS I think it will be around 90->82>76... -> 150>135>120

I was thinking around the same!

Reply 3517

BioStudentx

Original post by underestimate

What was the answer to the colour of the CuCl4 ligand as it wasnt mentioned that excess HCl was used?

Yellow?

Reply 3518

CSLady

Original post by underestimate

What was the answer to the colour of the CuCl4 ligand as it wasnt mentioned that excess HCl was used?

The colour of the ligand is still yellow. The queen colour is just because both complex ions are in the mixture (it's an equilibrium)

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