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

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Did anyone else notice that on the last the question the melecular ion for Y was at 47, but there are no alcahols that can be formed with 47m/z. :confused:

that's the M+1 ion formed from carbon-13 (1.11% of naturally occuring carbon) whereas most carbon is carbon-12 so the peak you were looking for was 46 :biggrin:

Reply 901

shuty

Original post by amyyy24

Oh my days
For some reason for the last question I wrote 'ethan-propanoate' instead of 'ethyl-propanoate'
:rolleyes:

Other than that, it was much nicer than the 2010 F322 exam!

Thats what i did... :confused:

Reply 902

racheatworld

Original post by kimmey

lool ok jus to clarify there was no double bonds on any of the ones u drew - they were all saturated ??

Yep, no double bonds!

Original post by asif123

Guys whats the general feeling amongst you guys.....what do you think the grade boundaries will be like....I found itdecent apart from the question where it asked you about Methanol use....WHAT THE F*=* was that....I originally put down In spirits but then changed it to feedstock for chemical processes...but yeah grade boundary predictions anyone?

I put feedstock as well, it was the only thing I could think of that wasn't a fuel/solvent.
I think grade boundaries will be medium-to high, maybe 70-75 for an A? A lot of people, and I mean most people came out of it confidently, saying that it was quite a good exam, and they were only unsure on a few 2 markers. Having said that obviously, it doesn't mean that they did well, but the consensus was that it was a pretty good paper.

Reply 903

Joseppea

June 09: A - 75 | B - 65 | C - 55
January 2010: A - 77 | B - 68 | C - 59
January 2011: A - 71 | B - 64 | C - 57

Low 70s I'm thinking :|

Reply 904

conzag123

Original post by Moiiu

Structural Isomers were D & E

Unsaturated Hydrocarbon was F

Last question was ethyl propanoate

Enthalpy question was -1279

were D and E the aldehyde and ketone?

and was F cyclobutane ??

Reply 905

arvin_infinity

Original post by racheatworld

Incomplete combustion only produces CO + H2O, no CO2.

But am sure have seen somewhere in past paper with co2

It was only one mark..

Reply 906

chargedmachine

Hi, I hated this exam, pretty sure I haven't got an A. My main reasoning for this is I got the entire last question wrong, all for one small error!

Right so I identified the peaks in Y: C-O and O-H right? and then I identified the correct molecular ion (cant remember the number but it was right). Then i made the stupidest blunder in thinking a C-O and an O-H were in carboxylic acids. So Y went down as methanoic acid for me arrrrrgggghhhhh :frown:

Then X, i thought well to make an ester, it must be an alcohol. Made another drastic blunder in thinking that it was an aldehyde because it had an OH group and a C double O bond. Named it propanal. But I did work out its exact formula from the molecular ion and the percentage abundance - C3H6O2? I think, i cant remember.

So then I thought Z was methyl propanoate. Can't believe I made such STUPID ERRORS D: will I get any marks for this question whatsoever? the rest of the paper was mainly okay, i know i dropped a few marks here and there...really dont want to have to resit, but im so sure that final failure will result in a nice depressing B or even C.

If anyone could cheer me up, that would be cool :smile:

thanks

Reply 907

Rup

Original post by darkxangel

I put down lighting fluid-which is wrong, that's the only thing i could think of. I did ok, hopefully will get an A grade.

wat if i wrote resins for paints? any idea?

Reply 908

shuty

i forgot to write the n on the left of my monomer does that matter?>

Reply 909

conzag123

Original post by nereik6794

My teacher hated the textbook. I thought it went well with my CGP revision guide and the specification. 1000000x better than the OCR physics textbook!

agreed! OCR phsyics tetxbook is awful in comparison to the chemo one!!! Fun physics exam to look forward to in a week - my last exam but means a week of revision as the book and my teachers suck :frown:

Reply 910

bagelbe

Original post by arvin_infinity

Accidently +rep you

They ignore dots (radical) anyway so no need to worry

Right back at you :smile:

awesome! I'm pretty sure I got the equations right :gthumb:

Reply 911

WALMO

Original post by amyyy24

In terms of bond making and bond breaking, what is meant by exothermic? breaking more than making
What is meant by enthalpy change of combustion? blah blah in oxygen
Work out enthalpy change of formation -1279 (or something)
Why can enthalpy change of formation not be measured directly? high activation, more than one product...

Write equations for complete and incomplete combustion of methanol
What is it used for?

Equation for atom economy

N2 + O2 -> 2NO
(Endothermic reaction)
In terms of rate of reverse reaction and rate of forward reaction, explain how the mixture reaches dynamic equilibrium forward = reverse
Carried out at same temperature but a higher pressure, why does it take less time to reach dynamic equilibrium and why is composition the same? more molecules, collision theory, same moles on each side
Why cannot it reach equilibrium in a car engine?
What is enthalpy change of formation (+66 to +33)
What is meant by endothermic?
NO has is a radical, what does it tell you about the molecule?
How does it break down ozone?

Draw a tertiary alcohol of C4H10O
Name it
Draw the alcohol that can be oxidized to make butanone
List of processes
Which one is cracking
Which does not have 100% atom economy
Which forms structural isomers

Fermentation & atom economy & percentage yield

(10 mark)
1-bromopropane 1-chloropropane
Fission, reaction mechanism, equation, reaction rate differences

Which is saturated?
Which are E/Z isomers, which are structural isomers, shapes, explain bonding in E/Z

Adding H2 across methyl-cyclohexene double bond
2 isomers of adding HBr across methyl-cyclohexene double bond.

Name alkene used to make polymer (but-1-ene)
What do CO and HCl do to environment, what are chemists doing to minimize damage?
Importance of international protocol agreements?

Last question
Carboxylic acid – M/Z = 74
Alcohol = 46
Ester was ethyl-proanoate

thats what I can remember from the questions if anyone wants to make the unofficial mark scheme now (LOL cannot remember order at all)
:wink:

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

Reply 912

Flint_09

another use of methanol....

I SAID it can be used in alcoholic drinks!

DO U THINK IT IS RIGHT?

"Methanol (one carbon), the propanols (three carbons giving two isomers), and the butanols (four carbons, four isomers) are all commonly found alcohols — these three toxic alcohols should never be consumed in any form." wikipedia

Reply 913

|Alex

How do you draw it when 1-methylcyclohexan-1-ene or whatever it was reacts with HBr.

(edited 12 years ago)

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Reply 914

NRT

Messed up the last question, but overall was not too bad. Was surprised at the lack of maths required but hey.
From what i can remember this is what i got : just a little note i doubt that these will be correct.
Enthalpy change of combustion is the enthalpy change when 1 mole of a substance is completely burnt in oxygen (No need to mention standard conditions here as it didn't ask for standard enthalpy change.
Got -1279 for the enthalpy change.
+33 for the enthalpy change of formation.
Messed up the Ozone one.
Atom economy is important as in industry we require more sustainable systems where little waste is produced, both for the environment and so that the most is made from expensive reactants.
International cooperation is important to raise awareness for governments and people to recycle/ dispose of plastics carefully.
Burning of chloroethene creates TOXIC HCL gas and TOXIC CO which attaches to haemoglobin better than O2. CO2 contributes to greenhouse effects etc.
The first 4 alcohols are liquids as their molecules hydrogen bond with each other hence these are much stronger than the van der waals that act upon alkanes. The hydrogen bonding occurs from the difference in electronegativity between O and H in the OH group.
A Functional group is a group attached to and organic compound and determines its chemical properties.
The reason why poly methanol dissolves in water is because it hydrogen bonds with it.
The 10 marker in the middle was heterolytic fission, nucleophilic substitution, C-Cl bonds are the strongest and shortest. Drawing the diagram with curly arrows etc is probably 4 marks and you had to do an equation too.
The last one was ethyl propanoate which was the modal answer in my college
The shape one i put tetrahedral and linear, the latter appearing incorrect.
Incomplete combustion CH3OH + O2 -> CO + 2H2O
Complete combustion CH3OH + 1.5O2 -> CO2 + 2H2O
Hope this helps with making an initial markscheme, ill add more when my memory is a little less vague :smile:

Reply 915

nereik6794

Original post by conzag123

Not only does it talk loads of random stuff you don't need, the questions never make sense either! How did you find G481? I thought it went well, self taught myself as my teachers are terrible too. Well, one teacher is okay. I just didn't listen in mechanics very much, he was good at teaching waves though :smile:

Reply 916

|Alex

Original post by Flint_09

another use of methanol....

I SAID alcoholic drinks!

DO U THINK IT IS RIGHT?

No. If you drink methanol you will kill yourself.

Reply 917

SmithytheDrummer

Original post by chargedmachine

thanks

It seems like you got at least like 4 marks there. Even if you dropped a good twenty marks you'd still get an A, so don't worry about it, just enjoy the rest of your exams <3