Chemistry (H)...

Richard_Fonzie

A pretty good paper overall I think. It wasn't easy by no means, there were some pretty difficult questions. But there were 1 or two very easy questions. The marks for questions were stupid however. 5 b) was worth 18 marks, and took about 30 seconds to figure out. 5 c) was worth 12 marks, and took about 10 minutes to get it down.
I was expecting to be on a B3 average, but every question rang bells in my head, and I got a good answer down for every question. Time for it was pretty crappy though, I finished with about 4 minutes to go (again probably because of badly placed marks). But it wasn't extremely hard, and I got it done... so overall a good paper for me.

How did everyone else do?

Cotsy

Ye that paper was nice (i hope) the Winkler yoke surprised me a bit cos i wasn expectin it but the Q wasn bad. I answered every Q except Exp3 and the very last Q, so i think i should be allright. Was only lookin 4 a pass. The prep of ethene in Section B was a nice surprise, but i didnt do great in the rest of that Q. so itl prob not count 4 me.

scorpy

I thought it was a pretty good paper, although the way they phrased the odd question was a bit confusing - Q1 g), for example, had me scratching my head for a minute. and Q2 e) was new on me, but I figured it out quick enough. also, Q10 b) i)?? what the hell?

I agree that the marks seemed a bit all over the place. Q5 took up maybe half a page for me, but part a) of Q10 had a page to itself! granted I wasn't sure about it so I spread out a bit on that one. so glad I didn't have to do le chatelier or thermochemistry!

overall, I'd say I got a good B, although depending on the quality of my 'I'm not sure but I'll go with...' answers it might be an A. did all the experiment questions; they were grand.

Cherry_Pie

I didn't like the paper! First paper so far Im not happy with!

Richard_Fonzie

My impression:

Section A:
1. - I was completely convinced that the winkler method wouldn't come up, and neither would any other water experiment (since one came up last year). Guess what? It did.


2. - All the signals screamed Ethanal, and the paper delivered. Questions weren't what I expected (first feature was limited dichromate/excess ethanol, what was the second?). Fehlings was suprisingly the only one of the 3 tests I didn't learn, so yay me. Part e) was a nice handy maths question, probably should've been worth more marks.

3. - I looked at this an hour before the test started, and I'm happy Hydrogen Peroxide came up. Questions again weren't what I expected, but I don't think they were too difficult.

Section B:

4. - Some of these were slightly tricky (in wording), but there was a fairly wide variety.

5. - Very easy, straight out of the book (if you had looked at it). Only part I was unsure about was b) i), trends of atomic radius across the second period. Are there any exceptions, other than it just decreasing?

6. - a) was straightforward, although i) was difficult to remember (I guessed wrong, answer was: heptane & 2,2,4-trimethylpentane). b) was straightforward (I think) and had too many marks for it (18), since all you need to do is draw the formula and write the name. Unless there's some kind of technique for it, I just wrote the general name (and wrote the name with the positions of the methyls for the particular formulas I put down). I got c), but I think alot of people found it very hard. Not enough marks for it (12), since it pretty much took into account several ways of using heats of reaction (formation, combustion, hess's law). Putting in two moles of benzene (when heat of combustion is for one mole), was a subtle trick that probably caught alot of people.

7. - Straightforward, especially if you knew the table in the Chemistry Live! book. c) was lengthy (basically the ethene experiment), but there were no tricky questions in it. Maybe it caught out alot of people who didn't study for it (because it came up recently). d) was tough (evidence for mechanism), I could only think of 1 (no reaction in darkness) and had to make up 2 others which I think were right (addition of tetraethyl lead and formation of butene from free radicals).

8. - Was very easy. Easy definitions, very basic principle of acid/bases for b). c) might've been difficult, but once you know the formulae it's extremely easy. d) I got the number of days wrong (5 & 7), but other than that I probably didn't lose many marks. e) was lengthy, but I remembered it perfectly for some reason.

9. - Didn't do. b) was straightforward if you had done the experiment (le chatelier), but it looked very lengthy and you had to write a balanced equation/write down the different observations. c) looked lengthy, but straightforward.

10. - a) I found this difficult, although I got it in the end (took 15-20 minutes). Straightforward questions using the theory, just hard to get your head wrapped them. b) another easy question, all observations on first ionisation energy. Only problems would have been lots of english/description that you need to write down, and the bad wording of the questions ("would it take more or less energy to remove the most loosely bound electron from an atom if that electron were not in its ground state" - almost a double negative, yet it isn't). c) Didn't do, looked easy if you knew chromatography, just probably took alot of english/description.

11. - didn't have time to do, otherwise I would have. a) seemed easy enough, you just had to be familiar with examples of electrochemistry. b) (my option) looked very very easy too. Considering you need to learn 5 plastics, and 1 and a half other chapters, this was really just based around 1 plastic so very little covered by the question, not to mention that Teflon is the easiest plastic to remember.

On another note, similar things came up in the Physics Paper and the 'Physics & Chemistry Paper''s physics section. And ethanal & basic electrochemistry (As longs as alot of smaller questions) appeared on both Chemistry and the Physics & Chemistry Paper. Could be a coincidence, or otherwise a blunder - but it didn't stop me from making sure to know ethanal!

sixdraw

a bit unfair i thought to go looking for the balanced equtions in le chateliers and the way they gave the compounds was confusing as they only show the ions in the books. apart from that i got everything done so icant complain, tricky in places allright, by no means simple

sixdraw

oh and i know i got my bleach prediction wrong but right before the exam in our locker area i was asking everyone why were the reagents in winklers concentrated so i keep my reputation

sci0x

Mmm, well you have to know the balanced equations, so you can tell what stuff to add where and makes more sense when you are writing an answer when you write out the equation. I used the one with cobalt chloride ions but I thought it was unfair to give you the substances and use them so you couldnt use the FeCl3 equilibrium exp as some ppl in my class had only that one learned off.

Yeah i spose was tricky in places but nothing that couldnt be figured out after 10 seconds of thinking about it. Overall thought it was simple, so pretty positive I got an A1.

Doctor D-Man

I really dont know what to think of that paper. There were parts I found easy (experiments in section A - I did 1 and 3). Even though every1 was saying ethanal would come up I didnt have timne to study it in detail and thus a few questions put me off doing it.

Q4 was easy enough - definitely got 8 parts right, attempted 10

Q5 easy again

6 couldnt do part (i) never even seen that in the book before. didnt get the third isomer and my calculations for the last bit didnt work out

7. what were the classifications for the reactions. I dont know if I'm right or not. said compund was chloroethane? Then I hadnt a clue for the last part. I literally wrote nothing. Could even hazard a guess.

8 skipped it because I forgot the last part, other than that It looked easy enough. I just alway mix up sewage treatment and water treatment.

9 looked too hard so I left it

10: did (a) not sure if my calculations are correct but I'd say I had the right methods
and (b) easy enough

11 (a) not sure if my answers are right but I guessed something anyway
(b) easy enough

Overall I hope I got a B. Otherwise I wont be counting chem for points....

sixdraw

all those questions involving ethanol, cant wait till after applied maths when i'll be doing a bit of organic chemistry allright. sixdraw-OH

CoffeeFreak

I loved that paper! It wasn't particularly easy...I think it was the same difficulty as previous years. There were a few tricky bits in it, like in the question where you had to get the atoms of helium in the balloon (haha), I did the whole question with stp volume (22.4L), before seeing that it gave the volume at room temperature as 24L. Luckily I had time to change it . And in the H2O2 experiment question, what did y'all (I'm gone western there ) say for how to record the starting time accurately? I forgot the right answer...

Scarinae

It was a nice paper, but with wankish combinations. I had to leave out the water chapter and the electrochemistry chapter, which was a bad idea cos then a LOVELY acids&bases question came up - but mixed with sewage treatment. And oxidation and reduction came up - but mixed with electrochemistry. Luckily I knew all three experiments though, so I managed it ok. don't think I got my A1 though grrrrrrrr

sarahg_angel69

thought it was alrite ye.... apart from some of the qts were phrased very badly!! very badly!! the atomic radius one?? wtf!! did it anyway!! qt6 was sooooo handy!!! loving the heat of formation qts!! whhhoo!!! but ya no wat...m ffrrreeeeeeeeeeeeeeee wwhhhhhhooooooooooo!!! hope everyone did alrite!! x

Richard_Fonzie

Paper

Question 7, a): A is chloroethane, W is elimination (dehydration), X is addition, Z is substitution (HCl for H2), Y is Addition (HCl added in). Those were the ansers I had anyway

For Question 4. e): I think I ended up with something like .05 CM^3 per second (converted from minutes to seconds).

ashmurph

i thought ya it was a fair enough paper. the experiment questions were lovely, and question 8 was perfect. i agree though that the marking scheme was a bit ridiculous. but overall im happy with it, hope i got d a. and now im finally finished!! yipee!! best of luck to everyone doin applied maths

colin300

well i am finshed!!!!!!!
that paper was easy enough not amazingly easy but easy enough.
Stuff i had studied like the winkler method and sewage treatment came up and a few other things i cant think of.

But I PASSED

7% in the mocks to a pass. I am pretty chuffed with it.

Scarinae

Hey, good job Colin! it's cool that you stuck with the higher paper, most people probably would have dropped to ordinary

scorpy

Richard_Fonzie wrote:

Paper

Question 7, a): A is chloroethane, W is elimination (dehydration), X is addition, Z is substitution (HCl for H2), Y is Addition (HCl added in). Those were the ansers I had anyway

I kicked Q7's ass and I'm so happy about that. mechanisms always used to kill me.

somebody mentioned Q6 i). I had a moment of 'wtf??' in the exam when I saw it referring to two reference hydrocarbons. I skipped 6 in the end because it looked like too much work compared to, say, the cakewalk that was Q5. looked it up in my book afterwards and they were looking for 2,2,4-trimethylpentane(or iso-octane) and heptane. 'twas only mentioned in passing in my book.

still wondering about Q10 b) i). anyone?

For Question 4. e): I think I ended up with something like .05 CM^3 per second (converted from minutes to seconds).

I'm guessing you meant Q3 e)?
I got 7cm^3/minute for mine(I wrote down all my numbery answers on my paper when I was done). of course the method we used in my class for getting instantaneous rate isn't as complicated as the one in the book, so I may have gone horribly wrong somewhere.

sci0x

The atomic radius one just came to me in the exam. Of course if two atoms are beside each other the atomic radius is half the distance between two adjacent nuclei.

I had never seen the reference hydrocarbons so I just wrote down the most effective and worst effective in influencing the octane number and wrote down heptane and 2,2,2 -trimethylpentane which is right according to some ppl here.

Coffeefreak to record the time accurately place hydrogen peroxide into test tube in conical flask. Attach string to it. Pull string to spill H202 over onto manganese dioxide and start clock at the same time.

colin300

well it was funny a guy got the honours paper and we were sitting there 5 mins before with the paper cause the examiner was reading out the correction.
Section A Question 1 Part C Line 1 8th word solution to solutions i believe.
So he is there sitting and we are waiting for him to say ok begin when a guy puts up his and goes actually could i do pass???

It was funny. But obviously he didn't let him drop down because he had seen the paper. Last minute gitters I suppose! Didn't get to ask him what he thought though after.

CoffeeFreak

Coffeefreak to record the time accurately place hydrogen peroxide into test tube in conical flask. Attach string to it. Pull string to spill H202 over onto manganese dioxide and start clock at the same time.

Oh, that's complicated, way better than what I wrote . We actually had discussed it in class and were told that putting the H2O2 in a separating funnel and starting the clock when you open it is the easiest way! It's a pity I forgot that in the exam .

phantom_lord

Good paper i thought, i agree though that the way some of the marks given was a bit odd, that a) part of 10 took ages compared to other sections.

I got 9 qs done in 2hours

Checked over for a while and put in a tenth question, that equilibrium q was a bit scary looking so i stayed away, made a couple of mistakes but i'm still hoping for the a1

scorpy

ehh, for the H2O2 question I just put down what we did in class - one person adds the MnO2, somebody else starts the stopwatch at the same time.

Breezer

I've heard of the string thing before; a simpler way is to have the MnO2 in a small test tube inside the flask, then tilt the flask slightly so that the MnO2 comes into contact with the H2O2 and immediately start the clock - basically the same thing, they'll take either I'm sure and probably a few other methods. With the diagram, labels, and how to collect it all featuring in the same question it'll be a maximum of 6 marks I'd say (and that's if the Q was worth 18, I can't remember) so I wouldn't worry too much - remember you can get an entire question wrong and still get an A2

I'm guessing you meant Q3 e)?
I got 7cm^3/minute for mine(I wrote down all my numbery answers on my paper when I was done). of course the method we used in my class for getting instantaneous rate isn't as complicated as the one in the book, so I may have gone horribly wrong somewhere.

7.1 I think I got - 7 point something anyway and the entire class seemed to get that

I knew iso-octane and was going to guess heptane for Q6, I'm really annoyed I didn't now cause Q6 looked so easy apart from that! My friend got it and said it to me afterwards and I was kicking myself cause I messed up the colours and which side of the equation the equilibrium was on at first in Q9 :mad:

Reckon I still got the A1 though - fingers crossed

6 down, 2 to go...

sixdraw

I suppose in all fairness to the exams comission the paper was almost as predicted, just jumbled up a bit

Brendygg

ya the paper was grand hopefully A1 say got A2.looked at the pass paper on examinations.ie twas very tricky talking to my brothers mate whos a chem teacher and he said u cud give it as a mock honours paper, the organic was nearly the same as honours q1 ethanal Q3 H2O2 Q7 was on organic rxns and was just as hard as the honours.check it out

D-Generate

I'm hoping I get an A1.
Alas I think I would just cut it if I did so its my worry that I didn't lose 40 marks.

jacksie

where the **** was bleach, water of crystillisation, and clove oil ffs!?

sixdraw

yeah i was a bit surprised allright that there wasn't one of them but ethanal and winkler were widely tipped to come up