Year 12s: what will be the first way you research your future options? >>

This discussion is now closed.

Check out other Related discussions

OCR Chemistry F322~ 4th June 2013~ AS Chemistry

Scroll to see replies

I'm not sure but i put:

IBr --> I + Br

Prop1: CH4 + Br --> Ch3 + HBr
2) CH3 + IBr --> CH3I + Br
Termination --> Br +Br ---> Br2

and the bond fission etc stuff.

Ah yeah, thinking about it, I definitely messed up on Prop2, there was no I₂present! Ah well, 2 marks gone haha

Reply 3381

the A* guy

The uploader on TSR is not working, so i managed to get the first 5 pages on to a PDF on a website domain. Bear with the link, it might take a while to load.

Rest of the pages to follow soon.

http://examwizard.yolasite.com/resources/Scan-12.pdf

Hope it helps!

Reply 3382

samiwami

It was an easy paper but I still fopped lol

Made the daftest mistakes and messed up on the IR question and more D:

I hope y'all do well, but I suggest not stressing about it now because it's over and we have the summer to enjoy!!

Reply 3383

Lysipud

Original post by niceguy95

7064J
So 7.06 Kj

Then divide by 0.005

Enthalpy change of reaction is the molar quanities...there was only one mole in the equation so you would of had to divide 1/0.005 which is 200 then 200 x 7.06 = 1412

Anyone else or just me lol...

Reply 3384

reneetaylor

Original post by yodawg321

Dont you have to say because it was the only product formed?

That's what I put, looking at mark schemes that answer should be alright.

Reply 3385

hayjamro

G was C5H10O as it was a 5 carbon alcohol with a Alkene group

Reply 3386

Gotzz

Original post by yasmin.mahfouz

I put 'use plant grains in plastics' the examiner is going to be judging me so bad

Posted from TSR Mobile

I'm glad I'm not the only one that had no idea :biggrin:

Reply 3387

anonymousecheese

i wrote it was an addition reaction and there is only 1 product formed, no desireable product

Reply 3388

bliam

Original post by joe1545

Im still questioning whether Anaerobic conditions will get the mark, because it said two essential conditions, when surely the reaction can happen in aerobic and anaerobic, the anaerobic bit is just a bonus... I may be wrong

Is saying "no oxygen (sealed container)" OK?

Reply 3389

Gotzz

Original post by hayjamro

G was C5H10O as it was a 5 carbon alcohol with a Alkene group

I got that :biggrin:

Reply 3390

cyiarik

A SORT OF UNNOFFICIAL MARK-SChEME (MAY BE OUT OF ORDER)

First Question
- C10H22
- (drawn) any branched isomer of c10h22 AND named [ i put 2-methylnonane ]
- (cracking question) C15H31 ----> C10H20 + C5H12 (any suitable equation-
- why does cracking hydrocarbons produce many products? C-C bond can break anywhere in the hydrocarbon chain
- (drawn) cyclo-octane i drew both skeletal and displayed formula of this just in case
- cyclo-alkanes are made because they burn more efficiently/ have a higher octane rating

Other question answers :
- homologous series: molecules that have same functional group but each successive member differs by a CH2
- burns with black smoke due to imcomplete combustion/ black smoke and yellow flame indicates there was a lack of oxygen therefore it did not combust completely.
- [question about why does something have 100% atom economy] because there was only 1 product produced in the reaction/ no waste products were produced in the reaction

Question about weird looking molecule thing showing E/z isomerism:
- functional groups present were an ester and an alkene (c-c double bond and a c-o double bond o)
- structure j is different from structure i because in I both the groups are on the same side of the double bond (Z isomerism) whereas in J each group is on the different sides of the c-c double bond (E isomerism)
- colour change of bromine: orange to colourless
Box Drawings for products of Alcohol when
1-oxidised
2-reacted with a carboxylic acid
3-dehydrated/hydrated

•

1st box was and ester or an aldehyde (may have to draw both)

•

2nd box was an ester + H20

•

3rd and 4th boxed were dehydration/hydration

For the question about halogenoalkanes:
- most unreactive: i put the first one (N)
- Most reactive one had 2 halogens in it (I and Br)

- P had a lower b/p than Q because P contained Br and Q contained I. The C-I bond is longer than the C-Br bond, thus it is easier to overcome the C-I bond as it experiences less attraction to the nucleus of the C atom/ takes less energy to overcome C-I bond.

Had to choose one of the halogenoalkanes to demonstrate electrophilic addition (1) + diagram

For the Le chatelier question:
increasing temp: favours reverse reaction/position shifts to reduce temp, backward reaction endothermic
removing catalyst: does not affect position of equilibrium
[not too sure about these^]

Define stereo isomers: have the same structural and molecular formula but different 3D arrangements of atoms in space

graph with percentages : 195.2 (approx) of something to 1 dp

i got 96.9% as the yield of something to do with propene (i cant remember)

got something like 4956 (approx) for the hess cycle question

4.96 X10-3 moles (of something cant remember again lol)

820 kjmol-1 as the enthalpy change when 230dm^3 is produces from N2 and O2

82 kJ as the next answer

NO question
no + o3 --> no2 + 02
no2+ 0---> no +o2
overall = o3 + o ---> 202

For yeast question:
C6h12o6 ---> c2h50h + c02 (i forgot to balance do i lose a mark?)

conditions of fermentation reaction: 37 degrees Celsius (not sure if this counts), fermentation is anaerobic therefore NO OXYGEN, yeast as catalyst

CFCs - biodegradable alternatives:
i wrote HCFCs because i had NO idea, anybody know the answer?

Mass spec of Sulphur
M+ was the value of the furthest line to the right
S8
the m/z was the base (tallest) peak
S4+

free radical question:
Initiation: IBr ---> I* + Br* (in presence of UV)
Propagation 1 : Ch4 + Br* ---> Ch3* + HBr
Propagation 2: ch3* + IBr ----> CH3I + Br*

for propaation 2 i wrote Ch3* + I* -----> CH3I (but its wrong because its a termination step ! silly me!!!)

Termination step (any two radicals added)

The bond fission was homolytic (because 1 e- from the covalent bond goes to each atom)

Working out the X and Y substances from the IR spec:
empirical formula gave c4h8O
i got that it could be an aldehyde or a ketone (due to absorbtions stated)
i drew the aldehyde and ketone structure but didnt name them, will i lose a mark?

For the bolztman distribution:
temp: 2 curves, one lower than the other
increasing temp1 increases the mean energy of the particles therefore particles collide more and have more successful collisions

catalyst: 1 curve, 2 activation energy lines shown
adding a catalyst reduces the activation energy meaning more particles have the sufficient energy required to overcome the energy barrier to react. thus a greater rate of reaction.

(edited 10 years ago)

Reply 3391

TheFootyKing19

- C10H22(1)

- 2-methylnonane (any branched isomer) (2)

branched isomers have: (2)
- fewer points of contact
- so less/weaker VDW forces
Cracking (1) any cracking equation:
C15H32 ---> C2H4 + C13H28

Why are they so many products: (1)
- in the hydrocarbon chain the C-C BOND can break from anywhere

Reforming of octane (2) (accept writing/skeletal formula
- Octane ----> 1,2dimethlycyclohexane + H2

Branched isomers: (1)
promote more efficient combustion/increases octane number/reduces knocking/combusts easily

Question 1 out of 9 marks

Reply 3392

bluedate

In my working out I got 820, but I think i put a wrong number on the answer line, will i lose the marks??

Anyone!! - stressing here!!

Reply 3393

Lysipud

Original post by amin666

Ketone and Ester

It was an ester and an alkene...the part you think was a ketone was part of the ester so couldn't of been .

Reply 3394

344302

Why was a yellow flame and black smoke ..

Was it incomplete combustion??

Posted from TSR Mobile

Reply 3395

Saurus95

Original post by joe1545

With the question where it was why does the reaction have 100% atom economy, even though it didnt as Hydrogen was being produced what did people say? I said because hydrogen is also a desired product as it can be sold on or used in process such as the hydrogenation of an Alkene, an example is the manufacture of margarine... Anyone?

I did not see an equation for that reaction (I had the enlarged paper). Aside from the atom economy section, what other parts were in that question? I know about the equilibrium section and the drawing the polymer but there wasn't anything else.

Reply 3396

reneetaylor

Original post by Lysipud

Enthalpy change of reaction is the molar quanities...there was only one mole in the equation so you would of had to divide 1/0.005 which is 200 then 200 x 7.06 = 1412

Anyone else or just me lol...

Don't think it makes a difference, got the same answer! :smile:

Reply 3397

bliam

Original post by estudiante_numero1

Was the absence of a catalyst for the Boltzmann distribution question and the equilibrium question earlier on? How many marks was the absence of a catalyst worth? I can't remember those questions particularly well, but I've just realised due to rushing I started writing about the addition of a catalyst, whoops. :tongue:

Overall I thought it was quite an average paper, so will hopefully will fairly average grade boundaries! :smile:

Posted from TSR Mobile

Hmmm, think that it was just below average; meaning just above average boundaries :s-smilie:

Reply 3398

such

Original post by Lysipud

Enthalpy change of reaction is the molar quanities...there was only one mole in the equation so you would of had to divide 1/0.005 which is 200 then 200 x 7.06 = 1412

Anyone else or just me lol...