OCR B Salters - F335 Exam - 15 June 2011

I thought they were asking convert ethene to ethandioic acid?

That is also correct isnt it ?

Looking at all the answers from ManPowa I've definately lost 21 marks minimum (probably quite a bit more). I was hoping maybe for an a*, that's out of the window. The exam was awful and some mistakes i made were ridiculous, for example, i did the electron configuration of Sulfur using it's Ar. I revised a lot aswell.Hmph.

Nope not ethene, it was from, 1,2dibromo ethane to ethanedioic acid.

It was a lot of synoptic stuff. Like electron shell diagrams & bond angles. Come on?

I think that it was bad on OCR's part that F335 was before F334... I feel that if they were the other way round, I would have done better :'D

Yup, I did the jan 11 paper 2 days before the exam under exam conditions and managed 92 marks, it was a lot easier than this, but yeah, it's strange having it in reverse order, I'm resitting f334 after having done it in january aswell.I didn't expect it to be so synoptic, I revised every single reaction, from the past 2 years and there was a tiny question on it and my teacher said their shouldn't be much synopticity apart from that and mechanisms, which i thought would be true looking at the jan 11 and jun 10 paper, clearly not

83/75/68 I reckon

Hmm, id say a bit higher than that (sadily)

86/78/71. It wasnt a 'solid' paper

But that would mean it being rated the easiest paper of the last 3.. which I really don't think it was.

Question 5 - 27 marks

HPO42- Hydrogen phospahe(V) with phoshorus being +5

Conjugate acid : H3Po4

Ka = products - reactants

Ph = 4.10

Buffer solution and why important in human cells:
Buffer solutions are solutions that main a constant PH on addition of a small amount of acid or alkali. Consists of a weak acid and its base and a weak base and one of its acid. Important in cells, as PH affects enzymes, thus it is vital a buffer soltion is in place, to keeps enzymes constant

Explain what the buffer solution does on addition of acid:
Moves to the left to absorb the acid. (2 marks - what else???)

Ph of a buffer solution: 10... something lol

Mass of solid NaH2Po4: (4 marks)

Why 7.4cm3 of NaOh was required: there was 15.0cm of Nah2po4 - to reach the end point, 2 moles of Naoh of 7.5cm3 was required

Error in the students argument: ??/


Enthalpy diagram:
exothermic reaction -
top lines - gaseous ions
then enthalp of hydration
and then arrow down for exothermic and thus enthalpy of solution as the reaction was negative.

Hi, I'm new to this whole forum thing, I just wanted to say that I re-sat chemistry of natural resources this year and I think it gave me unfair advantage due to all the synopticity in the paper. I was thinking this was rather unfair and wondered if anyone else who re-sat CONR this year found it - OK. Cheers

I was also wondering if anyone knew what the oxidation question was I think I put that sulfur was both oxidised and reduced but this is probably wrong, any help?

You're right!

It was oxidised from 0 to 4 and reduced from 0 to -2

4 marks in the bag

Why was SF6 a gas room temp but hexanedioic acid is a solid (it was a 4 marker)??