The Student Room Group
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>

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

Scroll to see replies

The first part of the bromine number question was 390 if anyone cares - my teacher did it today!

Also, people are talking about the grade boundaries being released? Idk how this is possible but could someone link me them if they are??
Original post by Marli-Ruth
I only got 228 UMS at AS :frown:


For an A this year I needed to be at least 6 marks into the A so hopefully F335 saves me!
Original post by kidlikethat
The first part of the bromine number question was 390 if anyone cares - my teacher did it today!

Also, people are talking about the grade boundaries being released? Idk how this is possible but could someone link me them if they are??


What was your teachers verdict upon the paper as a whole?
Original post by LewisEdwards1234
What was your teachers verdict upon the paper as a whole?


He hadn't seen it when we had our lesson, but he said by the sounds of it they decided to throw a curve ball with the style of questions. Although he didn't seem that surprised considering as when this was written it was going to be the last one, and apparently they tend to do this sort of thing with the last couple of papers of a spec
PM me if you want to join the group on FB for f335 and also aqa biol4. No begs so far everyone on there is helpful and not just leeches for info

Posted from TSR Mobile
Reply 585
Avatar for millss
millss
3
guys, for the question asking about how youd measure the rate of reaction, i said colorimetry because bromine was produced? is that not right? heard people talking about iodide ions but dont remember those being produced
Original post by millss
guys, for the question asking about how youd measure the rate of reaction, i said colorimetry because bromine was produced? is that not right? heard people talking about iodide ions but dont remember those being produced


Yeah that's what I wrote! I don't remember iodine in there at all oopsie
A mixture of 50cm3 of ammonia and 50cm3 of oxygen is allowed to reach equilibrium. The total volume is then 105cm3. All volumes are measured at the same temperature (above 100°C) and pressure.
Calculate the percentage of ammonia that has been converted to NO.
Can someone help me, I have no idea how to aNswer this

Also does anyone have any god revision helps or anyThing?
Original post by kidlikethat
Yeah that's what I wrote! I don't remember iodine in there at all oopsie


I did that reaction for my coursework so I know that bromine is a coloured liquid and all of the reactants are colourless. So I see no reason why colorimetry wouldn't be right. :smile:
Reply 589
Avatar for Kaz_96
Kaz_96
8
has anyone got access to the paper that can upload it here??
Am I the only one who put zero order for (bro3-) and first order for the other two?

I'm sure that was it? You had to be careful because you couldn't just think "as conc doubles, rate doubles" because for some, e.g. if it was first order, the conc remained doubled when we were looking for a change for a different reactant if that makes sense?
Original post by Kira Yagami
Am I the only one who put zero order for (bro3-) and first order for the other two?

I'm sure that was it? You had to be careful because you couldn't just think "as conc doubles, rate doubles" because for some, e.g. if it was first order, the conc remained doubled when we were looking for a change for a different reactant if that makes sense?

I also put the same as you for the rate equation!
Original post by geor_thor
I also put the same as you for the rate equation!


do you think it's right? I checked it 3 times? Please confirm it lol
Original post by Kira Yagami
do you think it's right? I checked it 3 times? Please confirm it lol


Yes I think it is correct. I kept doing the calculations and always came out with the same answer!
Original post by geor_thor
Yes I think it is correct. I kept doing the calculations and always came out with the same answer!


It was first order. The concentration halved and so did the rate.
Original post by geor_thor
I also put the same as you for the rate equation!


It was second order for H+ and first order for the other two
Original post by geor_thor
Yes I think it is correct. I kept doing the calculations and always came out with the same answer!


Sorry to say this but I did the reaction for my coursework and I know the actual rate equation is first order for bromate and bromide and second order wrt H+. I suppose that doesn't necessarily mean that the rate equation in the exam is the same though.
Original post by _MAT_
If they are all equally volatile, they'll all evaporate at the same rate so concentrations will remain constant

If one is more volatile than the others, the concentration will change so rate will change

If source of H+ ions is more volatile, it'll have more of an effect on the rate


I put that the way of measuring rate would be to use colorimetry as bromine is coloured. Then when it said the volatile bit i thought it would be that the bromine vaporises out of the solution as it is produced so the colorimetry would read a lower rate than the reaction actually was. But i didn't think the reactants would be effected as they were aqueous in solution so in the same way as when you boil salt water the salt doesn't vaporise out, the reactants here wouldn't.
Reply 598
Avatar for emfs
emfs
2
what does everyone think will be an a? nearer to 60 marks or 70 marks?
Original post by emfs
what does everyone think will be an a? nearer to 60 marks or 70 marks?


Probably around 63 maybe even 62

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you