Edexcel paper 2 chem unofficial mark scheme

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For the activation energy question I got around -7000 as my gradient and therefore got +53.97kj for my activation energy. I also got 10.11g for the mass of nitrogen using the pv=nRT. A lot of my friends got similar answers!

The general consensus here seems to be near 84 for Ea and 21.97 for nitrogen gas

Reply 61

Florent venhari

Original post by Yusuf121

I got +84.5 (something like that)

Reply 62

mohsam

Original post by glad-he-ate-her

Organic synthesis- conc no3, conc h2so4 goes to nitrobenzene then add tin and conc hcl to phenylamine then add ethanoyl chloride ( with no halogen carrier) to desired product
Ea was 84000 nearabouts joules, and divide for kj
mass of nitrogen was 21.97
Orders were x-1 y-2 z-0 k was 241.11
Diff proton nmr, one had 5 one had 4 intensity was like 3 to 2 to 2 to 1 and 1 to 2 to 2 to 2 to 1
find chemical shifts from data booklet and state splitting patterns
24 DNPH derivates, orange crystalline forms, recrystallise ppt, find mp using capillary tube method- compare with database of known bradys reagent derivatives
catalyst was adsrorbption, bond weakening then desrorption- explain those terms
graphie and graphene was single layer of hexagons, bond angle 120 and poor electrical conductivity was answer
reforming equation was just make cyclic and balance with hydrogen
2NO+2CO---2co2 +N2 was an answer
conc of bromine was 0.255
paracetomal percent was 93.6

Haha unlike last time, I'm in full agreement with all of these mate! Although the graphite/graphene ones took a bit of thinking outside the box

Reply 63

mohsam

Original post by Florent venhari

I got +84.5 (something like that)

Same. They usually give a range for finding the activation energy questions, you will 100% get the marks if your value was between about +82 to +87 kJ per mole

Reply 64

mohsam

I think if you get a ton of nitrogen as your answer to a question asking how much are in car tyres, you may need to think about it that's realistic lol

Reply 65

Gerry-Atricks

Original post by mohsam

Haha unlike last time, I'm in full agreement with all of these mate! Although the graphite/graphene ones took a bit of thinking outside the box

Yeah that was a little cheeky, wording threw me off initially

Reply 66

Gerry-Atricks

Original post by mohsam

I think if you get a ton of nitrogen as your answer to a question asking how much are in car tyres, you may need to think about it that's realistic lol

Nah havent you heard about the billions of tonnes of extra nitrogen we pump into our car tyres every year, lucrative business that

(edited 6 years ago)

Reply 67

AhnafR

Original post by Florent venhari

Went over the paper with my teacher! This mark scheme is looking good too! Ngl, but think I got FULL marks! Hope paper 3 is as easy. 🙌

Do hydrogens in benzene have just one chemical environment in proton nmr? How many chemical environments were there for phenylethanone and phenylethanal?

Reply 68

Dank chemist

Original post by glad-he-ate-her

Organic synthesis- conc no3, conc h2so4 goes to nitrobenzene then add tin and conc hcl

You see I have a slight problem with that, when you reduce nitrobenzene you actually get a protonated phenylamine instead of a normal phenylamine therefore you have to reflux it with naoh. The problem was they didnt give naoh as a reagent...did anyone else get stumped by this?

Or i may be overthinking this...its been a long day

(edited 6 years ago)

Reply 69

AmyBalint

Original post by glad-he-ate-her

Oh yeah i dont even think i put it thinking back.
Pretty certain on 84000, few of my friends got the same

It said write it in kJ/mol therefore it would be 84 surely

Reply 70

mohsam

Original post by AmyBalint

It said write it in kJ/mol therefore it would be 84 surely

Yeah your answer should be between +82 and +87, make sure you had the sign. It wanted the gradient value, which if I remember correctly was like -10,000?

Reply 71

AMA7777

Original post by AmyBalint

It said write it in kJ/mol therefore it would be 84 surely

think he meant in j per mol which then needed to become kj per mol

Reply 72

dub345

Original post by AMA7777

think he meant in j per mol which then needed to become kj per mol

Average of 75% on track for an A???

Reply 73

xxVENUSx

Think I did pretty well, I left the synthesis route question because I didn't even know how to do that.

Reply 74

richardhello

Original post by xxVENUSx

Think I did pretty well, I left the synthesis route question because I didn't even know how to do that.

Form in to nitrobenzene, then reduce to phenylamine, then react with ethanoyl chloride. Simples!

Reply 75

AhnafR

What did you all write for the proton NMR of phenylethanone and phenylethanal?

Reply 76

mailboxhotbox

for the organic symthesis, for my last step i used ethanoic acid instead of ethanoyl chloride to get a leaving group of water. dyou think thats ok?

Original post by glad-he-ate-her

Reply 77

Gerry-Atricks

Original post by mailboxhotbox

for the organic symthesis, for my last step i used ethanoic acid instead of ethanoyl chloride to get a leaving group of water. dyou think thats ok?

Its fine chemistry wise
practically- lower yield and less efficient
but you will get full marks provided rest was ok

Reply 78

JVardy

For the question asking about the conversion of the ketone into the alcohol...i thought it was a primary alcohol for some reason and so instead of just using LiAlH4 in dry ether as a reducing agent, I said to add I2 and NaOH to the ketone product which would form a carboxylic acid and then reduce that using LiAlH4. Would that still get me the marks?