You are Here: Home

A2 F335 OCR Salters B 2012 - Questions

Announcements Posted on
Take our survey to be in with the chance of winning a £50 Amazon voucher or one of 5 x £10 Amazon vouchers 28-05-2016
1. Hi,

Does anyone know how to answer questions 5.f.i and ii?

As well as question 1.c.iii. If you go by the n+1 rule then you'd surely have a splitting value of 4 and then 2? How could it be zero both times?

I cant seem to figure it out :s

Here's a copy of the paper and mark scheme if you don't have it:
http://www.thestudentroom.co.uk/show...3#post37931943

Thank you
2. (Original post by TheStudent.)
Hi,

Does anyone know how to answer questions 5.f.i and ii?

As well as question 1.c.iii. If you go by the n+1 rule then you'd surely have a splitting value of 4 and then 2? How could it be zero both times?

I cant seem to figure it out :s

Here's a copy of the paper and mark scheme if you don't have it:
http://www.thestudentroom.co.uk/show...3#post37931943

Thank you
I've just done this paper so will write up some solutions in a second.
3. For 5) f) i)
A student sets out to make a buffer solution. The student measures out 27 cm3 of
0.050 mol dm–3 HA solution and reacts it with one-third of the volume of 0.10 mol dm–3 sodium
hydroxide needed for complete neutralisation.

HA + NaOH --------> NaA + H2O

So first of all the moles of Acid HA.
n = C X V / 1000
n = (0.05 X 27) / 1000
n = 1.35X10-3 moles

As the volume added was a 1/3 of the require volume to neutralise, the amount of moles in the volume actually added will be the moles required / 3.

So...
actual n = (1.35X10-3) / 3
actual n = 4.5X10-4

V added = (n X 1000) / C where C is the concentration of sodium hydroxide

V added = ( 4.5X10-4 X 1000) / 0.1

5))ii)
Here you use a lot of the values you calculated above ^^^
moles of HA added to the solution = 1.35X10-3 moles
moles of A- added to the solution = 4.5X10-4 moles

For part 2 I have 0.2 less than the mark scheme so going to have a quick check of the ol' solutions before I post this.

And for 1)c) if you draw out the structure you'll find the there is in fact an oxygen between the CH3 and the H bonded to the oxygen. This there is no splitting.
4. (Original post by Mathlete 4 the win)
For 5) f) i)
A student sets out to make a buffer solution. The student measures out 27 cm3 of
0.050 mol dm–3 HA solution and reacts it with one-third of the volume of 0.10 mol dm–3 sodium
hydroxide needed for complete neutralisation.

HA + NaOH --------> NaA + H2O

So first of all the moles of Acid HA.
n = C X V / 1000
n = (0.05 X 27) / 1000
n = 1.35X10-3 moles

As the volume added was a 1/3 of the require volume to neutralise, the amount of moles in the volume actually added will be the moles required / 3.

So...
actual n = (1.35X10-3) / 3
actual n = 4.5X10-4

V added = (n X 1000) / C where C is the concentration of sodium hydroxide

V added = ( 4.5X10-4 X 1000) / 0.1

5))ii)
Here you use a lot of the values you calculated above ^^^
moles of HA added to the solution = 1.35X10-3 moles
moles of A- added to the solution = 4.5X10-4 moles

For part 2 I have 0.2 less than the mark scheme so going to have a quick check of the ol' solutions before I post this.

And for 1)c) if you draw out the structure you'll find the there is in fact an oxygen between the CH3 and the H bonded to the oxygen. This there is no splitting.
Thanks for this!

For all those calculations, I still can't believe question 5.f.i was only one mark. Seems pretty harsh to be honest!

Why is there no splitting? wouldn't the CH3 have to split from the O atom?
5. (Original post by TheStudent.)
Thanks for this!

For all those calculations, I still can't believe question 5.f.i was only one mark. Seems pretty harsh to be honest!

Why is there no splitting? wouldn't the CH3 have to split from the O atom?
Only adjacent hydrogens next to the CH3 cause splitting, because oxygen isn't hydrogen, it doesn't split anything =]

This was posted from The Student Room's iPhone/iPad App
6. (Original post by TiTo20)
Only adjacent hydrogens next to the CH3 cause splitting, because oxygen isn't hydrogen, it doesn't split anything =]

This was posted from The Student Room's iPhone/iPad App
We were never taught that but anyways thank youuuuuu! it all makes sense now lol.

Good luck for next wednesday guys!
7. Does anyone have the Jan 2012 F335 and F334 paper and mark scheme ?
Thanks alot
8. (Original post by kishenp)
Does anyone have the Jan 2012 F335 and F334 paper and mark scheme ?
Thanks alot
9. Does anyone have the marksheme for June 2012 salters a2 f335 just done it today and am very anxious!

Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: June 13, 2012
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

Don't be a half-term hermit

How to revise this week and still have a life