Unofficial Mark Scheme CHEM2 June 2013 COMPLETED

Original post by 4lpha

Can I ask why it's hydration and not hydrolysis?? xx

Hydration is something gaining water. Hydrolysis is a substance dissolving in water and seeing which part will join with the H and OH. I got that question wrong as well. Oh well, it is just one mark. :frown:

Reply 82

Secret.

14

Original post by Wick3d

Which means I didn't lose another 3 marks. :biggrin:

I stupidly wrote "Silver" instead of "Silver Nitrate" because for some reason the HNO3 confused my brain! So 9 out of 12 marks for that particular question. :smile:

ah damn! It's annoying making silly mistakes it doesn't actually prove that you didn't know the theory :frown:

Reply 83

rugbymad123

Original post by Wick3d

Hydration is something gaining water. Hydrolysis is a substance dissolving in water and seeing which part will join with the H and OH. I got that question wrong as well. Oh well, it is just one mark. :frown:

Precisely so it was hydrolysis. WATER WAS NOT GAINED.

Reply 84

Original post by harrydry

pretty sure both will get you the mark geezer

Ahaha cheers but I'm just hearing different things and I want to make things clear xx

Reply 85

Original post by Secret.

ah damn! It's annoying making silly mistakes it doesn't actually prove that you didn't know the theory :frown:

Oh well, I probably dropped about 15 marks. I just love having brain farts. Especially after having the ****s all morning, due to eating some dodgy pizza hut! Word of caution, never eat pizza hut before an exam! :biggrin:

Reply 86

darkred

20

Original post by rugbymad123

Precisely so it was hydrolysis. WATER WAS NOT GAINED.

Maybe it was adding water (hydration) to the reaction which caused the hydrolysis? Works...in both ways. :colonhash:

idk what im saying

I put dehydration because I forgot.

Reply 87

Original post by rugbymad123

Precisely so it was hydrolysis. WATER WAS NOT GAINED.

I am now confused, did I lose or retain a mark...

Reply 88

Original post by Wick3d

Hydration is something gaining water. Hydrolysis is a substance dissolving in water and seeing which part will join with the H and OH. I got that question wrong as well. Oh well, it is just one mark. :frown:

Uggh I thought the molecule was splitting! But it was an alkyl hygrogensulphate going to an alcohol and sulfuric acid right?? Just read this and I'm so damn confused!! But yeah it is only one mark I guess xx

An alkyl hydrogen sulfate can be broken down to an alcohol and sulfuric acid by heating it with water (hydrolysis);

Read more: sulfate | Infoplease.com http://www.infoplease.com/encyclopedia/science/sulfate.html#ixzz2VHMzb3N0

Reply 89

Original post by failingatm

Maybe it was adding water (hydration) to the reaction which caused the hydrolysis? Works...in both ways. :colonhash:

idk what im saying

I put dehydration because I forgot.

Don't worry, brain farts are very common during exam period!

Reply 90

chernid

2

This is going to be stupid, but for the bit where it asked to mark on the Maxwell-Boltzmann distribution curve the Emp, for some reason I thought that you had to put the line just right to the peak rather than to the peak.

Reply 91

Secret.

14

Original post by Wick3d

Oh well, I probably dropped about 15 marks. I just love having brain farts. Especially after having the ****s all morning, due to eating some dodgy pizza hut! Word of caution, never eat pizza hut before an exam! :biggrin:

Hahaha I definitely will keep that in mind for next time :biggrin:

And good thing is you can lose up to 20-25 marks and still come out with an A/112+ UMS so all is still good :smile:

I just hope the mark scheme isn't so specific in some areas, it's easy to lose marks that way

Reply 92

Original post by Wick3d

I am now confused, did I lose or retain a mark...

This is so me right now ahahahha

Reply 93

Secret.

14

Original post by chernid

This is going to be stupid, but for the bit where it asked to mark on the Maxwell-Boltzmann distribution curve the Emp, for some reason I thought that you had to put the line just right to the peak rather than to the peak.

That would be the average energy :redface:

Reply 94

Jesss9

2

Original post by rugbymad123

Precisely so it was hydrolysis. WATER WAS NOT GAINED.

Yeah I think hydrolysis is right, that's what it is at A2 (for that exact reaction). I put hydration though because I had my chem 2 head on but I think it was hydrolyis! I'm pretty sure that doesn't come up in chem 2 though so maybe they'd allow both :smile:

Only one mark though!

(edited 10 years ago)

Reply 95

Original post by chernid

This is going to be stupid, but for the bit where it asked to mark on the Maxwell-Boltzmann distribution curve the Emp, for some reason I thought that you had to put the line just right to the peak rather than to the peak.

I am sure that will be fine, as long as you clearly labelled where you wanted the Emp to placed. Right at the peak right? :wink:

Reply 96