Edexcel Chemistry Unit 6A Practical - June 2006

Electrochemical method is possible but i think precipitation method sounds better. If n e one has answer scheme could u go though to see if similar question came up b4. Or if n e one has access to marking schemes for practical exams?

Reply 22

ArVi

13

Does anyone actually have practical past papers?

Reply 23

ArVi

Does anyone actually have practical past papers?

I have a few but none of them relate at all to this year's

Reply 24

I have some answer schemes and i dont find a similar answer there.

Reply 25

is it just me or are the hints really vague??
hmm i wonder what edexcel are up to..

Reply 26

ArVi

13

The hints are pretty vague, but then again we can't expect them to give us the actual questions, can we! :rolleyes:

We've however been told that we're getting a boiling point instead of a melting point.

Reply 27

LOL you misread me, i don't expect them to give us the actual questions, i don't think anybody does!
the first 3 hints are fine, they are pretty standard really, it's last question that i'm talking about.
i mean, "separating cations" ? is it really just about precipitation and/or electrochemistry?
i remember last summer i did the AS unit 3 practical, and all of us just copied the answer from our notes into the answer sheet for the final planning question.
i don't know, maybe it IS just me.

Reply 28

to be fair, they are as vague as any past planning questions...

Reply 29

I discussed this with my friends (these students r the ones hu have got world rankings) they jus said electrochemistry cannot be involved here watsoever.
Its jus to precipitate with the correct test. so all we need to do is to know all the tests really well and how to apply then in what situations

Reply 30

i guess i was kind of expecting something more challenging because precipitation isn't exactly A2 material, it's just basic chemistry. and almost everything about precipitates is in the practical guide! i was thinking along the lines of recrystallisation, fractional distillation, or something like that, ie. the new techniques that we have been taught at A2 level.

Reply 31

Shickles

i guess i was kind of expecting something more challenging because precipitation isn't exactly A2 material, it's just basic chemistry. and almost everything about precipitates is in the practical guide! i was thinking along the lines of recrystallisation, fractional distillation, or something like that, ie. the new techniques that we have been taught at A2 level.

Just wait till the synoptic 6b paper :redface:

Reply 32

usman_s

I discussed this with my friends (these students r the ones hu have got world rankings) they jus said electrochemistry cannot be involved here watsoever.

really?

Reply 33

Mustard-man

Just wait till the synoptic 6b paper :redface:

LOL that's true..

Reply 34

pathetique

guys, i do not care what you will say, BUT THANK GOD FOR THE RETARDATION OF THE SPECIFICATION.

University College London (Pharmacology) BBB- (Firm) :pwnd:

No Insurance :eek:

Reply 35

pathetique

guys, i do not care what you will say, BUT THANK GOD FOR THE RETARDATION OF THE SPECIFICATION.

University College London (Pharmacology) BBB- (Firm) :pwnd:

No Insurance :eek:

Reply 36

Well I agree with Shickles.. Best is to know it all.
Do u guys think compounds which will be given can be organic too as someone said b4? The planning is usually 6-8 marks (i think) so does this mean we wont get a complicated planning experiment? (by n e chance..)

Electrochemistry cannot be involved because the questions says first identify and then separate and if the question is suppose say.. 7 marks, 4 marks would be for application of correct test and 3 marks for separation so do u ppal still think recrystallization, fractional distillation would be involved?

and yeah mustard-man my friends are the ones hu got world ranking. One of my close friends got 300/300 in biology. she came joint 1st in the world with 100s of students, meaning there were hundreds of students hu got 300/300. And lol these ppal dont have n e influence on me.. or mayb i dotn learn n e thing from them

Reply 37

usman_s

Well I agree with Shickles.. Best is to know it all.
Do u guys think compounds which will be given can be organic too as someone said b4? The planning is usually 6-8 marks (i think) so does this mean we wont get a complicated planning experiment? (by n e chance..)

Electrochemistry cannot be involved because the questions says first identify and then separate and if the question is suppose say.. 7 marks, 4 marks would be for application of correct test and 3 marks for separation so do u ppal still think recrystallization, fractional distillation would be involved?

Ref bold part 1: That was me. My bad :redface:

Carboxylate ions are ANIONS, got myself a bit muddled up there! My sincerest apologies!

Ref bold part 2: You misunderstood me, I was saying I was expecting something like recrystallisation, fractional distillation, etc to come up instead of some simple precipitation exercise (since this is an A2 level practical, not AS). I did not say they will come up this year. From the past practicals papers that I have done, recrystallisation has always been quite popular.

Reply 38

Ok u misunderstood me lol. I didnt mean that u were saying that they "will" comeup. It was just a question i asked looking at the mark range of the planning exercise..

My teacher isint telling me n e thing more. The other day we did the experiment on finding the boiling point and it requires good analytic skills, its not simple.

n e ways. I was thinking if we could make sample questions here and then see if we could answer. Il try first.
Plan a series of tests to identify three compounds.
1)MgCl2 2)ZnSO4 3)carbonyl compound
Test in a way so each one is identified inorder and separate cations from 2 of the compounds.

*to the three suspected solutions add 2,4-DNP and observe orangish-red colour in only one bottle. It has to be either ketone or aldehyde.
*Warm this solution with ammonical AgNO3. If the compound is aldeyde then a silver mirror appears. Ketones donot answer this test.
*To the 2 remaining bottles add (aq) NaOH and one of the bottles would give white ppt. on further adding NaOH,turns into a colourless solution.
*To confirm the identity of MgCl2. (since NaOH is already added) acidfy with dil. HNO3 followed by AgNO3. the ppt should be white and should dissolve when (aq) NH3 is added.
*Mg2+ is separated from Cl- when AgNO3 is added. Mg(OH)2 is formed and AgCl is formed.
*Zn2+ is separated from SO4 when NaOH is added. Zn(OH)2 is formed.

Ok this doesnt really sound like it. Correct all the mistakes i made and comment on how the question should have been. I jus hope im not talkign to myself.

+ Can someone explain me the spectroscopy involved in the 2nd questions plz. I dotn understand how to do that last bit of 2nd questions. rep will be followed.

Reply 39