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

j_pratt_2003

It was 33.

Equation was

N2 + 2O2 -> 2N02

Enthalpy Change of Formation of N02

1/2 N2 + 02 -> NO2

66/2 = 33.

http://chemistry.about.com/od/thermodynamics/a/Heats-Of-Formation.htm

About halfway down, on right hand side column. Formation of NO2 = +33.9

Reply 1221

TattyBoJangles

19

Original post by j_pratt_2003

It was 33.

Equation was

N2 + 2O2 -> 2N02

Enthalpy Change of Formation of N02

1/2 N2 + 02 -> NO2

66/2 = 33.

http://chemistry.about.com/od/thermodynamics/a/Heats-Of-Formation.htm

About halfway down, on right hand side column. Formation of NO2 = +33.9

Aha! I knew it!
All my friends called me silly - "You only had to look at it to see it was 66!". I started doubting myself and convinced myself it didn't show 2NO2.
I know it was only a one marker, but that's made me happy :L

Reply 1222

racheatworld

17

Original post by king1234

what did you get for the equilbruim one about pressure

I already posted this answer quite a few pages up, let me find it..

The equilibrium question was asking you why it took shorter time for the reaction to get into a dynamic equilibrium with pressure increase. Basically, this was rate of reaction increasing, more particles per unit volume, more frequent collisions, more successful collisions etc.

Then it also said why does the composition of the mixture not change with an increase in pressure? This is because increase in pressure favours the side with the least gaseous moles, in the equation both sides had an equal number of gaseous moles (both had 2) so position of equilibrium did not change, there was no NET effect on composition.

Reply 1223

king1234

Original post by racheatworld

I already posted this answer quite a few pages up, let me find it..

The equilibrium question was asking you why it took shorter time for the reaction to get into a dynamic equilibrium with pressure increase. Basically, this was rate of reaction increasing, more particles per unit volume, more frequent collisions, more successful collisions etc.

Then it also said why does the composition of the mixture not change with an increase in pressure? This is because increase in pressure favours the side with the least gaseous moles, in the equation both sides had an equal number of gaseous moles (both had 2) so position of equilibrium did not change, there was no NET effect on composition.

kk thanx lol

Reply 1224

Rosi M

11

What did you guys write for the question on how could we deal with the waste of plastics or something? It was before the international co-operation question? :s

Reply 1225

Amylase1234

Hi guys for the reaction of 1-methylcyclohexene with hydrogen, did you draw a straight chain alkene as the formula of 1-methylcyclohexene is C7H12?

Reply 1226

cashmoneyorg

7

Any unofficial mark scheme as of yet???

Reply 1227

Jim Lee

1

Original post by bradshawm05

Hi guys for the reaction of 1-methylcyclohexene with hydrogen, did you draw a straight chain alkene as the formula of 1-methylcyclohexene is C7H12?

I put methylcyclohexane, as the addition of hydrogen would get rid of the double bond in the cyclic molecule.

Reply 1228

Phenylethylamine_

Original post by bradshawm05

Hi guys for the reaction of 1-methylcyclohexene with hydrogen, did you draw a straight chain alkene as the formula of 1-methylcyclohexene is C7H12?

All it was that you had to remove the double bond but keep the methyl group on it, i.e. draw methylcyclohexane :smile:

Reply 1229

king1234

Original post by Jim Lee

I put methylcyclohexane, as the addition of hydrogen would get rid of the double bond in the cyclic molecule.

could you draw it out here lol if you dont mind how it would look and how would the other two look when you add hbr

Reply 1230

akydon619

Original post by king1234

does anyone think the grade boundaries will be lower for this one i found it harder than june2010 and jan 11 anyone agree lol if not im stuffed wont gte my A

onda same boat me friend i think grade boundaries should be down defo it was much harder than june 10 and bit harder than jan 11, i may miss my A aswell

Reply 1231

king1234

Original post by akydon619

onda same boat me friend i think grade boundaries should be down defo it was much harder than june 10 and bit harder than jan 11, i may miss my A aswell

yara i revised for chem a swell inshallah we will get the grade man

Reply 1232

04001

Does anyone know why for the question:
which process is not 100% atomeconomy?
If was the ester and water one and not the cracking one?

Reply 1233

Kir4nK

7

for the 2-methyl-propan-2-ol i put methylpropan-2-ol .... is this not considered as the same thing as the methyl can only actually be on the second carbon therefore would i still get the mark pleaseeeeee say yes :frown:

Reply 1234

king1234

Original post by Kir4nK

for the 2-methyl-propan-2-ol i put methylpropan-2-ol .... is this not considered as the same thing as the methyl can only actually be on the second carbon therefore would i still get the mark pleaseeeeee say yes :frown:

might not i think do you have to put the dashes in i got 2-methyl-propan-2-ol but didnt but the dashes in

Reply 1235

StrawberryKoi

12

Original post by king1234

might not i think do you have to put the dashes in i got 2-methyl-propan-2-ol but didnt but the dashes in

wooooooo i got the same answer as you

.....again :lolwut:

Reply 1236

Nick526

1

Original post by Kir4nK

for the 2-methyl-propan-2-ol i put methylpropan-2-ol .... is this not considered as the same thing as the methyl can only actually be on the second carbon therefore would i still get the mark pleaseeeeee say yes :frown:

I think you are correct, I put that too because the 2-methyl is not needed as there is no other place that it could be. The '2-' is unnecessary
Don't worry :biggrin:

Reply 1237

Kir4nK

7

Original post by king1234

might not i think do you have to put the dashes in i got 2-methyl-propan-2-ol but didnt but the dashes in

i mean i put all the dashes and all that crap lol but did there need to be a 2 infront of he methyl because from my understanding even f there was no 2 infront of the methyl it still would nt matter because the only carbon the methyl can attach to is the 2nd one otherwise it wouldnt be methylpropan-2-ol ???????

(edited 12 years ago)

Reply 1238

king1234

Original post by StrawberryKoi

wooooooo i got the same answer as you

.....again :lolwut:

erm what did you get for that question a bout the atom aconomy ones

Reply 1239

Kir4nK

7

Original post by Nick526

I think you are correct, I put that too because the 2-methyl is not needed as there is no other place that it could be. The '2-' is unnecessary
Don't worry :biggrin:

oh k tht makes me feel awhole lot better lolll :smile:

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

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