The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

OCR A Chemistry F322 Chains, Energy and Resources Thu 19 Jan 2012

Scroll to see replies

Original post by niaghez
I don't think it was cyclopentene because it had a methyl group attached to one of the carbons too


maybe we're talking about different questions. But there was a question which required you to draw two repeat units of the polymer formed from cyclopentene specifically.
Original post by faz_341
is the defination for standard enthalpy of formation:
the enthalpy change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions 100kPa and 298k
(3marks)


Yes, but I would always state a temperature of 298K and pressure of 100kPa, rather than just the units alone.
Reply 782
Avatar for niaghez
niaghez
Original post by citylights
maybe we're talking about different questions. But there was a question which required you to draw two repeat units of the polymer formed from cyclopentene specifically.


I only remember one question to draw two units so if you're sure it was cyclopentene.. Then FML :frown:
Reply 783
Avatar for niaghez
niaghez

Ohh and also, you know where we had to write a readction between A and B (I don't remember what they were) to form one molecule of C and two molecules of D.. Did you put 2D or D +D? Would both be right because I wrote D+D
Original post by niaghez
Ohh and also, you know where we had to write a readction between A and B (I don't remember what they were) to form one molecule of C and two molecules of D.. Did you put 2D or D +D? Would both be right because I wrote D+D


I remember the question, it was about the cracking of C16H34 to produce an alkane and two molecules of butene, I wrote:

C16H34 --> C8H18 + 2 C4H8

I'm not 100% you'll get both marks or the single mark (can't remember if it was a one or two marker), I can't see a reason why you shouldn't though!
Reply 785
Avatar for Messi3
Messi3
1
is there an unofficial mark scheme?
Original post by Dan12
it's done under reflux


Aaaaahhh I'm an idiot. :frown:

Oh well hopefully I still got 3/4 on that one.
Original post by Eternal Rest
Aaaaahhh I'm an idiot. :frown:

Oh well hopefully I still got 3/4 on that one.


4 marks:
-propan-1-ol
-H2SO4
-reflux
-equation
Yeah I put all of them except the reflux bit.
3/4 is good enough for me I suppose. xD
Reply 789
Avatar for faz_341
faz_341
Original post by citylights
4 marks:
-propan-1-ol
-H2SO4
-reflux
-equation


did u have to put h2so4 i just put acid catalyst :s-smilie:
Reply 790
Avatar for holahola
holahola
Original post by faz_341
it was
* 50 x 4.18 x 12.8
*0.486/24.3
* -2.68/0.02 = -143 i think :smile:


I multiplied part c by 2 cos there was two moles! Is that wrong
Reply 791
Avatar for holahola
holahola
How many marks are lost if the Boltzmann thingy touches the axes? Xxx
Original post by citylights
draw two repeat units of the polymer formed from cyclopentene specifically.


That was hard, think I lost that mark :frown:
Original post by Lambo_93
That was hard, think I lost that mark :frown:


i just drew a line between them ?
Original post by Dizzie31
Not really to me :biggrin: i found the last 2 questions the easiest!


Hehe- same! :biggrin:
Reply 795
Avatar for kingam
kingam
what did everyone get for the last tow questions cant even remember what i did for mechanisms
I got nucleophilic substition and heterolytic fission.
Original post by Eternal Rest
I got nucleophilic substition and heterolytic fission.


yep, that's what I did :smile:
Original post by Debbie_xx
yep, that's what I did :smile:


for the two repeat units i drew a line between the cyclo one is that correc?T
Original post by NabilKhan
no change as the number of moles on both sides would have been equal


There were 3 moles on the left and 2 on the right

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you