All Chemistry A2 students, the planning question this summer... Watch

Mustard-man
Badges: 15
Rep:
?
#61
Report 12 years ago
#61
I very much doubt it'll involve recrysallisation because the method of recrystallisation itself is worth 8 marks, according to past mark schemes.
0
reply
har1s
Badges: 0
#62
Report 12 years ago
#62
ok i think the planning question is starting to get straight now.. like first the tests using NaOH or NH3...and then separation (either filtration or recrystallisation) ... so i think some1 should or WE should get one SINGLE plan.. that we'll write in the exam or whtever..but at least the basic standard outline of the plan that every1ns gonna use to write their plan... and then on the other hand..lets get questions 2 and 3 straight..
0
reply
har1s
Badges: 0
#63
Report 12 years ago
#63
and as RMIM said.. Al and Mg are not even transition metals... ?? so what about that.. ?
0
reply
Mustard-man
Badges: 15
Rep:
?
#64
Report 12 years ago
#64
(Original post by har1s)
and as RMIM said.. Al and Mg are not even transition metals... ?? so what about that.. ?
Well isn't unit 6 synoptic?
0
reply
chaos king
Badges: 0
#65
Report 12 years ago
#65
i think someone mentioned a technique on one of the previous pages to get the boiling point of a substance. i didnt find that very clear. could someone clarify...
also what compounds do you guys think will come up in Q's 1 and 2??
0
reply
har1s
Badges: 0
#66
Report 12 years ago
#66
hmm agreed... ^^ but isnt the practical test related to unit 5 and 4.. ? (A2) and there is a special SYNOPTIC test.. unit 6B.. right ?
0
reply
har1s
Badges: 0
#67
Report 12 years ago
#67
@ chaos king .. if you have nelson advanced science.. read page 121 of the Unit 5 book.. if u dont then ill try n explain
the best way to figure out a boling point of a substance is to carry out a distillation and observe the steady temperature when this occurs. But if the sample is small and u need to find out the boiling point of the substance...then Sivolobov's Method is used. sample is placed in a wide, thin-walled capillary tube, into which is placed a naroow cappilary tube, sealed at the upper end with its mouth below the surface. the whole is fastened to a thermometre with the liquid next to the bulb. this is placed in an oil bath and the temperature is raised slowly. air slowly escapes from the smaller capillary, until, at the boiling point of the sample, a rapid stream of bubbles occurs. then allow the oil bath to cool and record the temperature when the liquid first rises in the inner capillary , but for this a larger sample is required due to the evaporation. see also page 2 of this thread and i hope it will b clear enough.
0
reply
shabwasim
Badges: 0
#68
Report 12 years ago
#68
can any one explain what should we write in inference column?:confused:
0
reply
har1s
Badges: 0
#69
Report 12 years ago
#69
^^ which inference column ? i think for the inferences...its not a big problem..u'll have your notes with u most probably.. so just look up ur observations in ur notes for the corresponding inferences.
0
reply
Smashingdude
Badges: 1
Rep:
?
#70
Report Thread starter 12 years ago
#70
Okay The Half plan:

Question as far as i guess:
a)Plan a series of test to identify the given 3 solutions. The suggested solutions are among the following : Zinc Sulphte, Magnesium Chloride, Aluminium Sulphate. (its not sure it wud be these solutions but the cations are probably these) {The given things I suggest are NaOH and NH3 (aq) . {These both should be present or else u cant do it}

b)Two of the solutions are now mixed. Plan a series of experiment which would allow you to separate the ions in the solution. I am not sure of this question. Does this mean they have mixed solutions or we just have to take the cations out of the solution. Ill dig up more info on this and post it here. For now enjoy with a)

Part (a):

Label the solutions as A,B,C
Take about 5cm(cube) of A and pour it into a Test tube
Add 2cm(cube) of NaOH
A ppt forms.
Add excess NaOH and see if the precipitate dissolves
Carry out the test with the other 2 solutions.

Inferences:
If a white ppt forms and it doesnt dissolves in excess, then Mg ions are present in the original solution. Label the solution as MgCl
If a white ppt forms and it dissolves in excess, then either Al or Zn ions are present.

Now take 5cm(cube) of one of the other 2 solutions and pour it into a testube
Add 2cm(cube) of NH3
A ppt forms
Add excess and see if the precipitate dissolves.
Carry out the test with the other solution.

Inferences:
If a whit ppt whit is insoluble in excess reagent forms, then Alumunium ions are originally present. Mark the solution as Aluminum Sulphate
If a white ppt which is soluble in excess reagent, then Zinc ions are present. Mark the other solution as Zinc Sulphate


PLZ PLZ correct me if I am wrong. And get some more info. not much time guys..
0
reply
spacko101
Badges: 0
#71
Report 12 years ago
#71
as 2 of the solutions could be mixed together, do u think, once we seperated it, we have to test to see that they are infact seperated. ie. the remaining solution will react differently to the solid that we removed.
0
reply
har1s
Badges: 0
#72
Report 12 years ago
#72
Hmm..i dont really get your point @ spacko.
0
reply
Kieny
Badges: 0
Rep:
?
#73
Report 12 years ago
#73
(Original post by Smashingdude)
Okay The Half plan:

Question as far as i guess:
a)Plan a series of test to identify the given 3 solutions. The suggested solutions are among the following : Zinc Sulphte, Magnesium Chloride, Aluminium Sulphate. (its not sure it wud be these solutions but the cations are probably these) {The given things I suggest are NaOH and NH3 (aq) . {These both should be present or else u cant do it}

b)Two of the solutions are now mixed. Plan a series of experiment which would allow you to separate the ions in the solution. I am not sure of this question. Does this mean they have mixed solutions or we just have to take the cations out of the solution. Ill dig up more info on this and post it here. For now enjoy with a)

Part (a):

Label the solutions as A,B,C
Take about 5cm(cube) of A and pour it into a Test tube
Add 2cm(cube) of NaOH
A ppt forms.
Add excess NaOH and see if the precipitate dissolves
Carry out the test with the other 2 solutions.

Inferences:
If a white ppt forms and it doesnt dissolves in excess, then Mg ions are present in the original solution. Label the solution as MgCl
If a white ppt forms and it dissolves in excess, then either Al or Zn ions are present.

Now take 5cm(cube) of one of the other 2 solutions and pour it into a testube
Add 2cm(cube) of NH3
A ppt forms
Add excess and see if the precipitate dissolves.
Carry out the test with the other solution.

Inferences:
If a whit ppt whit is insoluble in excess reagent forms, then Alumunium ions are originally present. Mark the solution as Aluminum Sulphate
If a white ppt which is soluble in excess reagent, then Zinc ions are present. Mark the other solution as Zinc Sulphate


PLZ PLZ correct me if I am wrong. And get some more info. not much time guys..

It seems to work thus far man! Although im worried about the assumption that we have to make about both NH3 and NaOH being present.

What exactly and OFFICIALLY are the reactions of Al and Mg in NH3 and NaOH both dropwise and in excess ... PLease confirm - This is VITAL to the solution of the problem...
0
reply
spacko101
Badges: 0
#74
Report 12 years ago
#74
(Original post by har1s)
Hmm..i dont really get your point @ spacko.
i hope im not going crazy :confused:

ok i know that was hard to understand so i'll say it again.

we know that the seperating involves 2 of the solutions above being mixed together.

Say we seperate them. do we need to do any comfirmary tests to show that it is in fact, eg. Zinc and Magnesium; because it could also be Magnesium and Aluminium.

I think. if im talking BS just tell me to stop please
0
reply
har1s
Badges: 0
#75
Report 12 years ago
#75
^^..hmm yea that can b a possibility too .. so identifying the two substances wont b a problem... will it ?
0
reply
spacko101
Badges: 0
#76
Report 12 years ago
#76
nah it shouldn't be difficult, i'm just saying what might come up so everything gets into our heads.
0
reply
Kieny
Badges: 0
Rep:
?
#77
Report 12 years ago
#77
(Original post by spacko101)

Say we seperate them. do we need to do any comfirmary tests to show that it is in fact, eg. Zinc and Magnesium; because it could also be Magnesium and Aluminium.

I think. if im talking BS just tell me to stop please
SPACKO BY NAME - SPACKO BY NATURE...

Only Jokes - no i dont think we'll have to do confirmatory tests post separation...
0
reply
Harryz
Badges: 0
#78
Report 12 years ago
#78
Is this edexcel or AQA you guys talking about? Thx.
0
reply
Smashingdude
Badges: 1
Rep:
?
#79
Report Thread starter 12 years ago
#79
The reactions which i posted are confirmed. I dont think they will give us NaOH. Gammay_ray said

"The planning question, by elimination should be the identification of 3 unknowns, A B and C. You may or may not be given NaOH. Anyways you probably have to identify the NH3. This is easy with NaOH at hand and just as easy without
Anyways the 2 unknowns then need to be identified and seperated. It is going to be transition metal compounds and i guess again by elimination one has to to be a zinc (sulphate/nitrate or w/e) as it is one of the few which is a white ppt formation upon reaction with NaOh. Then i guess you can see wher the NH3 would come in. And then simply seperate using the standard method. EASY PEESY!
Hope this helpS!
GooD LUck!"

That means one of the solution must be NH3. The other 2 should be salt soultion of the ions(either Al Zn or Mg). Then it makes sense. And it can now be identified as well as separated.
0
reply
har1s
Badges: 0
#80
Report 12 years ago
#80
Edexcel @ harryz
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Latest
My Feed

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.

Personalise

University open days

  • Cranfield University
    Cranfield Forensic MSc Programme Open Day Postgraduate
    Thu, 25 Apr '19
  • University of the Arts London
    Open day: MA Footwear and MA Fashion Artefact Postgraduate
    Thu, 25 Apr '19
  • Cardiff Metropolitan University
    Undergraduate Open Day - Llandaff Campus Undergraduate
    Sat, 27 Apr '19

Have you registered to vote?

Yes! (477)
38.19%
No - but I will (95)
7.61%
No - I don't want to (87)
6.97%
No - I can't vote (<18, not in UK, etc) (590)
47.24%

Watched Threads

View All