OCR AS - Chemistry Unit F322 - Chains, energy and resource - REVISION!

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thanks

yeh hopefully we'll get the formula!
also are you the one who posted the notes on unit 2 in a world file? they were a life saver! thanx!

hope so

yeah i am, aww good! you're welcome

Reply 1041

thefirstnotlastsamurai

Original post by Music22

I remember something like that, but I can't quite remember it exactly... thanks though, hopefully I'm not going insane aha!

Lol i definitely remember it was question and no worries :wink:

Reply 1042

Music22

Grrrrrr so many stupid mistakes?!?!! Where was all the organic chemistry?!! Sorry, well done to all of you who did well aha!

Reply 1043

gradu

Original post by Abused Tampon

..............................

Same, whatever I tried I couldn't get it :frown:

Reply 1044

St.Jim

Original post by WALMO

pretty sure that is was meant to be a + for the hess's law thing cos it was formation using the combustion things , was quite a trick question, and everyone else got that at my school but yeah, and exothermic is bond making, endothermic is bond breaking :P

I had to think about this one. I saw that it was a formation, so I think it was products - reactants which gives a +ve enthalpy result.

If you think about it there must be energy taken in by the chemical system to make the new bonds - it can't give out energy when making bonds between elements!

Reply 1045

conzag123

Original post by thefirstnotlastsamurai

I thought the paper started off quite confusing but then got better.

My answers roughly - don't get disheartened/pissed off if our answers don't match, there's no guarantee I'm even right.

Respiration formula was standard.
Why is it endothermic Bond breaking is endothermic, bond breaking is exothermic, one outweighs the other, can't remember which one i put, nor do i have the mental capacity to work it out now.
Enthalpy question -2793 or something in that region.
Activation energy minimum energy needed to begin breaking reactant bonds and kick start a reaction.
Why cant you measure formation directly Activation energy is too high.

Dynamic system question - collision theory, more particles in same volume, closer together on average, all that jazz.
Car Exhaust not a closed system
Compare alkanes and alcohols I just waffled on about one has van der waal forces, the other has hydrogen bonds, hydrogen are stronger than vandewaals. And something about boiling points.
Name the monomer But-1-ene?

Ozone mechanism NO + 03 ------> N02 + 02 (1) NO2 + 0 ---------> NO + O2 (2) Overall: O3 + O ------> 2O2

Use for methanol Feedstock (just wrote that, not sure if i'll get a mark for putting just that)
Tertiary Alcohol 2-methylpropan-2-ol
Secondary Butan-2-ol
Why one dissolves in water Polar OH- group forms hydrogen bonds.
Complete combustion of methanol CH3OH + 1.5O2 -------> CO2 + 2H20
Incomplete CH3OH + O2 ------> CO + 2H20

Cracking Process 5 i think i put?
Isomer product Process 1?
One of the answers F
The other one ahah D&E

Drawing it First drawing just took the double bond out, next two, drew the methyl group, but then had the bromine next to the methyl group on one picture, then at the other point for the other.

Shapes Tetrahedral and then trigonal i think?

Mechanism was nucleophilic substitution, heterolytic, bromoalkane hydrolyzed faster because it was longer, weaker bond enthalpy and more reactive.

Ester Ethyl Propanoate and all that analysis ****.

All the green chemistry i just waffled **** loads - CO is poisonous/carcinogenic (i think that's a lie) contributes to acid rain? HCL (acid rain, ground level ozone?) And more stuff - which is probably all lies also.

Atom economy I thought was better - less waste, more sustainable

International treaty I invoked gandi and martin luther king as i began preaching about saving the world by reducing polymers.

That is all i can actually remember - hope any of that helps.
It's my third time doing it (got 118/150 both times) Keep resitting, your chemistry ability will continually get better.

Wish all of you luckk.

:wink:

from the bit i have emboldened, were D and E the aldehyde and ketone (i.e. structural isomers) AND was F cyclobutane (the saturated hydrocarbon) ?? im trying hard to remember here but can't... :biggrin:

Reply 1046

Kir4nK

if i used OH---K in showing my mechanism of the nucleophilic sub will i lose marks or was it meant to be just the OH???

Reply 1047

bites

Original post by Phenylethylamine_

Well, I retook this exam and for the use of methanol (which also came up in my unit 4 mock) it can be used in a transesterification process to make biodiesel. I just remembered that from my unit 4 exam so put that down! :P

Overall the paper was quite easy! :P xD

##

i wrote that it was used for methylated spirits!

Reply 1048

Saliency

I put that methanol can be used in antifreeze.
Is that too specific?

Reply 1049

shuty

Original post by Peanut

i showed both to be on the safe side

did u have to state that it was a nucleophilic substitution reaction?

Reply 1050

786girl

did u have to SHOW the heterolytic fission?
i just wrtoe that it was that, how would i show it?

Reply 1051

*Funky-buddha*

Oh good lord for the ten marker question I only showed nucleophilic substitution of OH- and didn't show anything to do with K?!

Will that be ok for the mechanism or will OCR'S sneakneyness mean I get marked down :O ¬__¬

Reply 1052

Tateco

Original post by *Funky-buddha*

The OH was all that mattered, nothing to do with the K :smile:

Reply 1053

medusa cascade

For the international question, I just wrote about sustainability and mentioned the Kyoto agreement thing...

Reply 1054

04001

for the last question what do you think each of the 10 marks were for

maybe

1 for ester elthy propanoate
1 for propan oic acid, 1 for oh absobtion, 1 for oh absorbtion, 1 for empirical fromula, 1 for molecular formula,
1 for ethanol, 1 for oh absorbtion, 1 for m+ peak
1 mark for written communucation

Reply 1055

Kir4nK

PLEASEEE some1 tell me if i used the K was a bad idea for nucleophilic sub?????? !!!!!!!

Reply 1056

*Funky-buddha*

Original post by tateco

The OH was all that mattered, nothing to do with the K :smile:

Aha thank you! I was having a little panic attack as I didn't even recall seeing K anywhere on the hydrocardon chain.
Note to self: Read question :tongue:

Reply 1057

bites

COULD SOME ONE SERIOUSLY HELP ME OUT PLS?

For the last question, i got ethyl propanote, but instead of writing down the name i just darw the structure of compound X, Y AND Z. Would that matter?
Secondly, u know for the shape questions, i put tetrehedral for the ist bit, and trigonal planar for the second.

Reply 1058

Peanut

Original post by shuty

did u have to state that it was a nucleophilic substitution reaction?

well, i did. i also stated heteroltics fission for both of them and said why one was slower and why the other was faster.

Reply 1059

thefirstnotlastsamurai

Original post by Kir4nK

PLEASEEE some1 tell me if i used the K was a bad idea for nucleophilic sub?????? !!!!!!!

You'll be fine - The K was irrelevant, as long as you showed that the OH was the nucleophile and Br- was formed at the end.

In my opinion all that matters is whatever reactant you used - as long as you done the complete equation with the right by-product NaBr, KBr, HBr or just Br- - I dont see any reason why you'd get it wrong.