AQA chemistry 3t (p13) ISA help please

Watch
Announcements
#1
just doing some past papers on the chem 3t (p13) isa, JUNE 2013 at the moment,

stuck on question 5a, any help on it please
(I'm using an average titre of 29.00 cm^3 for my answers)

I tried working it out by 1st working out the moles of Y using Q.4 x 5.00.
and then using the answer (moles) by dividing the mass 71.5 by the answer(moles).
If that makes sense. Obviously wrong because they are working it out differently in mark scheme so I think my answer would be wrong the way I worked it out.

Link to isa paper & mark scheme:

http://filestore.aqa.org.uk/subjects...TEST-JUN13.PDF

http://filestore.aqa.org.uk/subjects...W-MG-JUN13.PDF
0
6 years ago
#2
Hey there,

I'm just going to move this in to the Chemistry forum for you. You might be able to get some more responses there.
0
6 years ago
#3
What they have done is:

Step 1: calculate the concentration in gdm-3.
mass/volume = 71.50/5 = 14.3 gdm-3

Step 2: Divide the mass concentration by the mole concentration to get the Mr.
mass conc / mole conc = 14.3/Q4 = Mr

Proof: (mass/volume) / (moles/volume) = mass/volume = Mr

Your method is equally as valid and you would have got the marks. I would have done it your way too.

Hope this helped,

Mr L

(@MrL_Chemistry)
0
X

new posts
Back
to top
Latest
My Feed

Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Poll

Join the discussion

Should there be a new university admissions system that ditches predicted grades?

No, I think predicted grades should still be used to make offers (738)
33.95%
Yes, I like the idea of applying to uni after I received my grades (PQA) (928)
42.69%
Yes, I like the idea of receiving offers only after I receive my grades (PQO) (413)
19%
I think there is a better option than the ones suggested (let us know in the thread!) (95)
4.37%