OCR Salters Chemistry of Materials 2849

anyone remember anymore more answers?

i remember a few:-
test for phenols - neutral iron (III) chloride ---> purple
oxidation state of iron - +3
extra info needed to analyse affects of temp - enthalpy change of reaction
name of the molecule - 1,5-diaminopentane
type of reaction - ligand exchange

no particular order! but thats all i remember at the moment

Reply 43

Aranyani

djdan1990

anyone remember anymore more answers?

i remember a few:-
test for phenols - neutral iron (III) chloride ---> purple
oxidation state of iron - +3
extra info needed to analyse affects of temp - enthalpy change of reaction
name of the molecule - 1,5-diaminopentane
type of reaction - ligand exchange

no particular order! but thats all i remember at the moment

you've got exactly the same as me! god thats such a relief!

The one everyone was debating at our school was whether the amino acid was alkaline, neutral or acidic. Some said neutral cos the charges cancelled each other out and some said alkaline as there was an extra amine group..

who knows.

Reply 44

Aranyani

okay ignore me, its already been mentioned :p:

Reply 45

i said neutral because it was a zwitterion but everyone seems to think its alkali....
anyone know the answer for sure?

Reply 46

james s

7

Common sense dictates it is alkali.

I couldn't remember the rust stuff for sure, but I put down that the oxygen and water form 4 x OH- ions. Also got ~54% for the amount of Iron.
What did people put down for the very last question? I just blagged through three points.

Overall I felt it could have been a lot worse, but there were a few questions I wasn't sure on (hopefully I managed to hit enough key phrases in the chromatography one, and my diagrams were informative enough). If I remember anything more then I'll post again.

Reply 47

last question.... about catalysts??
i said it was a homogeneous catalyst and forms an intermediate
it oxidises to form Fe2+

Reply 48

djdan1990

last question.... about catalysts??
i said it was a homogeneous catalyst and forms an intermediate
it oxidises to form Fe2+

I thought it was a general question about Fe as a catalyst? I thought that it could be heterogeneous as well? For the ionic equation one about ligands, did people miss out the 6H20 as a product because its not an ion? Do you reckon it would be ok for that question about what else was needed to say whetehr the reaction is exothermic or enothermic? Or do you think you will have to be specific and say the enthalpy change? I wish I had never come on here my marks are seriously low! Oh and the manganese Q, was the colour change pink? Erm can't think of much else

Reply 49

mentally-guitarded

For the last one i put,
Iron being a transition metal produces ions with variable oxidation states. The Fe ions interconvert in the redox reactions and remain unchanged. The Fe ion also lowers the activation enthalpy for the reaction, allowing an alternative, lower energy reaction pathway for the reaction.
I remember doing a very similar question in one of the past papers, might have been the spec paper. These were the three points on the mark scheme.

Reply 50

O I put that it acts as a heterogeneous catalyst providing a surface for molecules to be adsorbed. Would that get me 1 mark?

Reply 51

j_c_rox

4

Why did peoepl get 54% my mates and I got 5.4% for the iron calculation!
Damn! I put neutral.
Eurgh! that 1st question about the calcium carbonate and the butanoic acid= ???

Which way did ppl draw the arrow for the way electrons move in that rust q- downwards or upwards? I did downwards

PET has perm.dipole, perm dipole right?

Reply 52

Aranyani

i drew the arrow upwards because the electrons move from the anodic area (the centre) which releases elctrons to the cathodic area which accepts electrons.

Reply 53

Biochemical Wizard

9

Hopefully everybody done alright

Reply 54

yeh i had an upwards arrow too.

Reply 55

lucasm

i may be exaggerating because i had a shocking maths paper but this was seriously difficult i think the word day of exams iv had so far this year. I'm so depressed right now its seriously going to be a long agonizing wait for results and the worst thing is i have to galvanize myself back into action to do chem by design general studies and business.

Reply 56

djdan1990

yeh i had an upwards arrow too.

FINALLY A MARK!

Reply 57

For the CaCO3 question I put Butanoic acid + CaCO3 - - - -> CH3(CH2)2COO-Ca+ + HCO3??? I have absolutely no idea if thats right but I remember a question about it but it involved Na not Ca. Oh no I think I might have put Na instead of Ca! My life can't get any worse right now :frown:

Reply 58

Calv

j_c_rox

Why did peoepl get 54% my mates and I got 5.4% for the iron calculation!

cuz the solution was diluted 10 times smaller than the original... so u need to time it by 10 afta uv found the mass.

yay, most of my ans r similar to those in this thread.

how come the zwitterion q is not neutral???

both NH3+ n COO- are present...

Reply 59