You are Here: Home

# OCR Chemistry B (Salters) F334/F335 Exam Thread 2016 (14th/22nd June)

Announcements Posted on
Would YOU be put off a uni with a high crime rate? First 50 to have their say get a £5 Amazon voucher! 27-10-2016
1. (Original post by rosschatburn)
I got 10

I worked out the concentration of the Bromine to be 0.075mol/dm3 from the previous question and equation, then used this to find the number of moles of bromine that was used up (from the volume that was added) for 10g of the hexene, from this found the mass. And then multiple by 10 to get it for 100g
I did this as well apart from I believe I multiplied by 10 once too many times so i ended up with 104, as 10.36 multiplied by 10. Hoping this is only the loss of one mark if 10 is the correct value
2. (Original post by LewisEdwards1234)
I did this as well apart from I believe I multiplied by 10 once too many times so i ended up with 104, as 10.36 multiplied by 10. Hoping this is only the loss of one mark if 10 is the correct value
Oh okay, that's equally reassuring! Yeah, if 10 is the correct answer you'll only drop 1. A mark for each of the method marks and then you just won't get the mark for the final answer, they should ignore the extra multiplication. No stress👌🏼
3. I said organic polymer for coating the cell. Is that allowed too?
4. (Original post by kosvengali)
Posted from TSR Mobile

Can we help each other with F335 my future depends on it
Yes mate we need to get something going got a fake fb account ready everybody is struggling but nobody wants to help anyone else

Posted from TSR Mobile
5. For that volatile question and the effect it has on the rate of the reaction, i swear im the only one who put it has no effect - my thinking was because it never told us which chemicals are actually volatile, i assumed only the products would be volatile as it was Br2 and water, whereas the reactants were ions. So loss of products would have no effect on the rate of reaction as the reaction would have already occurred and the rate is determined using the initial concentration of reactants rather than products. Confusing i know
6. (Original post by Tralph123)
for the rate equation i got H+ as zero order and the other two reactants as first order?
That's what I got too!

Posted from TSR Mobile
7. (Original post by marcus.dyer11)
So what are we saying for the 5 marker bromine question then? 7? 10?
I got 7. In the last question it said KBro3 was in excess so you needed to use Br-. Conc of Br- was 0.167 mol dm-3 therefore the number of moles in the solution of 0.0167 since there was 100cm3. Br- and Br2 were in a 5:3 ratio. So moles of Br2 would be 0.0167 ÷ 5 x 3 = 0.01002 moles and the previous question said this made a 200cm3 sample. The 5 marker then said 83cm3 reacted with 10g of the alkene so the number of moles of Br2 used was 0.01002 ÷ 200 x 83 = 0.0041583 moles. Mass would therefore equal 159.8 (Mr of Br2) x 0.0041583 = 0.66. This is the answer for 10g of the alkene and bromine number asks for 100g so you times this answer by 10 to get 6.6g and rounded up to the nearest whole number is 7.
8. Is there still a chance of me getting a B on this paper if I completely messed up all of the calculations?

Posted from TSR Mobile
9. For the standard electrode potential question, it was +1.8 V, not -0.26 as it said the sign was the same as for the half-cell with iron. Hence they both had to be positive meaning that as for iron it was +0.77, to get +1.03, it had to be +1.8 for the other one
10. (Original post by Zuzuvela)
Yes mate we need to get something going got a fake fb account ready everybody is struggling but nobody wants to help anyone else

Posted from TSR Mobile
LOL, that level of security, fair enough tho

I'll set it up tomorrow as I haven't 'friended' everyone yet but there is a decent amount of people so it should be effective 👍

Posted from TSR Mobile
11. Don't know if someone's asked this already but people are saying ocr released the grade boundaries today. If so, where can I find them? How can they release grade boundaries before they even know how people did? Surely a certain number of people have to get certain grades and that's how they usually work out grade boundaries? I'm so confused wtf they can't do this to me

Posted from TSR Mobile
12. (Original post by Marli-Ruth)
My coursework is the only thing saving my arse right now

Calculated at least 30 marks I've lost 💀😭
Lmao same

Posted from TSR Mobile
13. (Original post by brown_eyes)
Don't know if someone's asked this already but people are saying ocr released the grade boundaries today. If so, where can I find them? How can they release grade boundaries before they even know how people did? Surely a certain number of people have to get certain grades and that's how they usually work out grade boundaries? I'm so confused wtf they can't do this to me

Posted from TSR Mobile
You're correct. They aren't out yet

Posted from TSR Mobile
14. (Original post by lyricalvibe)
You're correct. They aren't out yet

Posted from TSR Mobile
Ah thank you

Posted from TSR Mobile
15. any tips for calculation questions in chemistry please? I'm okay at them, but not amazing - if they throw something new I might not be able to get all marks... so any tip?

I really think we should help each other, just ask random questions because it's so easy to obtain simple method marks in exams.

THANKS
16. (Original post by WittyGonStein)
For the standard electrode potential question, it was +1.8 V, not -0.26 as it said the sign was the same as for the half-cell with iron. Hence they both had to be positive meaning that as for iron it was +0.77, to get +1.03, it had to be +1.8 for the other one
That's exactly what I did, but then I had a hunch I saw the same value somewhere before and it was the same value (-0.26V) on last year's F334 paper too with the same half reaction
17. Anyone has the unofficial mark scheme? Was it one mark for the standard electrode potential question?
18. (Original post by WittyGonStein)
For the standard electrode potential question, it was +1.8 V, not -0.26 as it said the sign was the same as for the half-cell with iron. Hence they both had to be positive meaning that as for iron it was +0.77, to get +1.03, it had to be +1.8 for the other one
that was my reasoning too... hope were right!
19. (Original post by mikejordan97)
That's exactly what I did, but then I had a hunch I saw the same value somewhere before and it was the same value (-0.26V) on last year's F334 paper too with the same half reaction
So it was -0.26V right?
20. (Original post by Elle_w)
That's what I got too!

Posted from TSR Mobile
H+ was second order the other two were first order

Posted from TSR Mobile

## 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: September 16, 2016
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

### University open days

Is it worth going? Find out here

Poll
Useful resources