The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

OCR Chemistry A Exam Thread (Breadth - May 27 2016 and Depth - June 10 2016)

Scroll to see replies

Original post by jasonrose98
I'm sure I did. Was there another way? I ended up with 4.(something) mol anyways



I don't know, some people didi it using the one which involves molar mass... I think I got that too but i can't remember
Original post by asinghj
Mass of gas / Mr of gas


I never even thought of that:frown:
Original post by chloelaura27
I don't know, some people didi it using the one which involves molar mass... I think I got that too but i can't remember


I did the whole question like 3 times without looking at what I'd done the previous time and kept getting the same answer (which I now can't remember) so hopefully its fine:smile:
Original post by asinghj
Mass of gas / Mr of gas


I was going to do that but it was a gas????
Original post by SGHD26716
When thinking about grade boundaries we are to think about how people found it in general. I don't think every other person is getting 95% in them.
Would you say the TSR population is representative of all the people who did the exam?

I think 105 for an A. It would be as high as 115. A person who drops 10 marks in both papers (gets 86%) will only be 5 marks of a B. That is why O think 114-115 boundary is too high.


I agree with you. TSR population might not provide an actual representation so an A might be between 108-112 in my opinion.
Original post by jasonrose98
I never even thought of that:frown:


I thought that n= v/24000 wouldn't work as the question wasn't at RTP but you got the answer 4.something moles so 🙃🤑
Original post by chloelaura27
I was going to do that but it was a gas????


Still works because you had the mass and could calculate the Mr
Someone may have mentioned this before, but for the electrontic config was it an Mg atom or ion? I was like 99% sure it was atom but loads of people from my college said they changed it to ion at the last minute:s-smilie:
Original post by jasonrose98
Someone may have mentioned this before, but for the electrontic config was it an Mg atom or ion? I was like 99% sure it was atom but loads of people from my college said they changed it to ion at the last minute:s-smilie:


It said atom, I'm sure of it
unofficial mark scheme ?
Original post by jasonrose98
Someone may have mentioned this before, but for the electrontic config was it an Mg atom or ion? I was like 99% sure it was atom but loads of people from my college said they changed it to ion at the last minute:s-smilie:


it was an atom, I looked over it a couple of times to make sure 😅
Original post by amysed
it was an atom, I looked over it a couple of times to make sure 😅

I felt crushed when everyone said they'd done different 😅I came out thinking I'd done well:biggrin:
Reply 1112
Avatar for 11...
11...
9
where is the unofficial mark scheme???. please tell me the link for it. thanks :smile:
Reply 1113
Avatar for 11...
11...
9
Original post by iamDev
On the last question i messed up the formula and got propanoic acid. However i stated that the m/z is 88 and stated that there is an o-h bond and c = o bond. I stated that its a carboxyllic and and what the peaks 73 and 43 on the mass spec referred to. How many marks do you reckon ill get? Im thinking 2 max and possibly 0


if you got the empirical formula right and the fact that it is a carboxylic acid from the absorptions/peaks, then I guess you would get 3 out of 6
If you labelled Ea on that endothermic diagram, will you lose a mark
Original post by usmanahmed321
it was butanoic aCid
you had TO times the EF C2H4O by two to get C4H802 OF WHICH THE MR WAS 88
THERE WAS ALSO AN M/Z PEAK AT 88 SUGGESTING IT WAS BUTANOIC ACID
IT COULDNT HAVE BEEN C2H40 SIMPLY BECUASE THAT ISNT A CARBOXYLIC ACID
THE IR SPEC CLEARLY INDICATED IT WAS A C ACID
THE MAS SPEC ALSO SAID THE MOST INTENSE PEAK WAS CAUSED BY A CARBOCATION WHICH WAS AT 43 OR 44
SO THE MR WAS 88
anyone agree?


Agreed. That can be the only way.
Reply 1116
Avatar for 11...
11...
9
Original post by nwmyname
Agreed. That can be the only way.


it is methylpropanoic acid actually guys. it said that it was a secondary carbocation
Original post by Jitesh
Don't think peaks like 73 worked for butanoic acid.


Nope I Checked it did work
Reply 1118
Avatar for jn998
jn998
6
What would I get for the last question if I didn't talk about the other peaks on the mass spec?
I started off by saying it had to be a carboxylic acid because of the IR spectrum, then I used the ratios of elements to make the empirical formula, and then the second to last peak on the mass spec (88) to work out the molecular formula and then ran out of time. I was going to look at the other peaks but didn't get a chance so just wrote down butanoic acid. Would I lose more than 2 for this?
For the enthalpy question, did you have to label the axes and label Delta H?

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you