Need help on CIE Chemistry Paper 5!

[ashish]

Q3(d)

you have to work out the molecular formula let say your mean value for Cu was 2.00

element  mass    Ar          mole         /simplest
O           1.00    16.0        0.0625        1.98  =2
Cu          2.00    63.5        0.0315       1

Copper (I) oxide
CuO₂

hmm it is a fictitious value just replace yours and do the calculation



How did u get an average 2??? my average is 3.983 so the formula of copper oxide is CuO PLZ help..... thanks in advance

[ashish]

here is your answer

element  mass    Ar          mole         /simplest
O           1.00    16.0        0.0625        1.00
Cu         3.983   63.5       0.0627          1.00

answer: CuO

[Deadly_king]

what is the volume of water do we have to use?

Thanx a lot for ur help..

This will depend.

Example :
1) First experiment you used 50cm³ of a known concentration of solution.
2) Second experiment you are asked to use 30cm³ of the same solution. Since you need to keep total volume constant(50cm³), add 20cm³ of water

Anytime

[moon]

here is your answer

element  mass    Ar          mole         /simplest
O           1.00    16.0        0.0625        1.00
Cu         3.983   63.5       0.0627          1.00

answer: CuO

which value is a fictitious value??? mine or yours

[moon]

This will depend.

Example :
1) First experiment you used 50cm³ of a known concentration of solution.
2) Second experiment you are asked to use 30cm³ of the same solution. Since you need to keep total volume constant(50cm³), add 20cm³ of water

Anytime

did we assume that total volume will be 50cm3 in experiment?
Ur explanation is wonderful. You are doing a great job...thank u very much

[Deadly_king]

Ur explanation is wonderful. You are doing a great job...thank u very much

You're welcome buddy

[moon]

This will depend.

Example :
1) First experiment you used 50cm³ of a known concentration of solution.

Did we assume that the total volume is 50 cm³?

[Deadly_king]

Did we assume that the total volume is 50 cm³?

Nope that's not an assumption.

You'll be given the total volume to be used in the question itself. You'll have to adjust for the other experiments such that you keep it constant for all experiments by adding water.

[ashish]

which value is a fictitious value??? mine or yours

well the answer is

element  mass    Ar          mole         /simplest
O           1.00    16.0        0.0625        1.00
Cu         3.983   63.5       0.0627          1.00

answer: CuO

[moon]

Nope that's not an assumption.

You'll be given the total volume to be used in the question itself. You'll have to adjust for the other experiments such that you keep it constant for all experiments by adding water.

but the question did not include 50cm3

[moon]

well the answer is

element  mass    Ar          mole         /simplest
O           1.00    16.0        0.0625        1.00
Cu         3.983   63.5       0.0627          1.00

answer: CuO

thanx

[Deadly_king]

but the question did not include 50cm3

Well.........I was not being specific about a particular question!

It was just an example that I stated to help you understand.

Tell me which paper it is and i'll try to help you

[moon]

Well.........I was not being specific about a particular question!

It was just an example that I stated to help you understand.

Tell me which paper it is and i'll try to help you

Nov. 2009 ppr52 Q1 (e)

[Deadly_king]

Nov. 2009 ppr52 Q1 (e)

OK........but that will depend on the concentration you stated in part(d) for ethanedioic acid.

I just finished it now, but I do't have a scanner, so won't be able to upload it right away.

Am sorry I need to rush for now.........i'll be back later to elaborate. Same for your number in p2 Nov 07

Hope you don't mind

[moon]

ok thanx I will be waiting for ur answer