Yeah I know, even Wikipedia says a freshly exposed surface has a reddish-orange color.
Ah well, it's just copper and chromium then can ask us stuff like that for so as long as we learn them both it'll be fine.

Don't know if this is any help but I'm resitting the January exam for a better grade. There was A LOT on electrolysis and why copper was a good conductor. Will this be likely to come up again as the papers aren't online yet?

Hi,
They should be attached
Me :D

Hi

I have the AS practical tomorrow, it is my first attempt.

In preparation I am learning the following:

-Identification of organic liquid
-Qualitative Analysis
-Preparation of halogenoalkane
-Removing water of crystallisation
-Iodoform preparation
-Enthalpy of combustion
-Enthalpy of neutralistation
-Reacting elements with water
-Reacting elements with steam
-Titrations
-Calculations

is this enough/am I missing anything? How are you preparing?

Hi, does anyone have the mark scheme for january 2013 unit 2?

Ahaha, I've kind of learnt my mistakes at the beginning of year 11 when I realized that I knew absolutely nothing about what I was meant to be learning in year 10 so I started to panic (and I do triple science which made me panic even more) and I frantically revised everything I had learnt as well as the material I was covering in class, and lucky I had caught up and attained an A* in the mocks since my school updates you predicted grades according to your mock grades and all :L

It's never to early for anything I guess, ahaha.
I'm hoping to medicine in university :P I'm doing the Challenge a few days after I finish my GCSEs and then I'm going to be doing work experience in West Africa for a month (thank goodness I've got practically two months of freedom) and then when I come back, I have to call the elderly home to arrange the times I can go over to do some volunteering until the end of year 13 once I get my school timetable. I've got a pretty busy agenda when I come back, :P. I'll also be attending my Police Cadet squad on Thursdays, doing Judo on Wednesdays, working in Starbucks on Tuesday afternoons as well as having my tutoring study courses during the weekend and Altar Serving in Church on Sundays (Yes, I'm also religious)I've got to make sure that I also have to time do my school work as well as juggling all of this... God help me, I have no idea how I'll do it D:

I'm going to be so antisocial next year, the only friends I'll have is TSR and my parents ;) hopefully that won't happen, but this year, I spent my birthday revising instead of jamming with my buddies and playing video games together. :| I sound like such a geek ahaha, which I can hopefully assure you I'm not.. :$

I've sort of just realized how much I'm writing and how much you have to read about my GCSE/life dilemma ahaha, I'm sorry. :']

Does anyone have January 2005 CH4 paper? I can provide with some legacy CH5 ones if you do.

so did i ! i was shocked as i thought i had done ok :( i also would like an A but i'll settle for a B

Heard that edexcel papers are getting harder and harder each yearPosted from TSR Mobile

It works for me and the rest of us? :S

May I ask where to get this list of reagents and conditions? What exactly are they for?

Hey :) do you have the answers for the sheet on the advanced notice yet?:)

bit of advice please guys? I've been doing the questions on a-level chemistry, and the very last bit on each chapter is the booklet of past paper questions which I've started (I've done kinetics and equilibria) and I started doing the acids and bases today and it's over 400 marks worth of questions, I can't afford to do all of those :( Also wondering if I should do them at all- I don't want to start doing past papers for another two weeks, and I'd planned to do all the question booklets by then, but will the question booklets cover the past paper questions? Basically will it be the same stuff as the past papers on aqa or are they really old questions and should I do those or just do past papers now?

Thank you :)

Gas chromatography, with a liquid stationary phase,
Can someone explain why greater solubility reduces retention time?

And can someone explain why greater solubility in the liquid stationary phase means a high retention time

can anybody post and unofficial mark scheme pls? :S

If its ok to use pencil for graphs, then why not, as long as it was a suitable pencil, but Its always better to use black pen.

I really struggled with this question too, but after looking it up in my revision guide I've cracked it!
I think it forms a buffer solution because it's a weak acid mixed with a strong base of a lowish concentration. The acid is in excess because of it's concentration- meaning some of the acid is neutralised to make its salt but some is left un-neutralised. Therefore the reacting mixture would have a weak acid and it's salt- a buffer solution.
For calculating the pH:
CH3CH2CH2COOH+NaOH(in eqm)-->CH3CH2CH2COONa+H2O
Number of moles of CH3CH2CH2COOH= c x v/1000= 0.25 x (50/1000)= 0.0125 mol
Number of moles of NaOH= 0.05 x (50/1000)= 0.0025 mol
As there is so much more acid than alkali, the acid is in excess- meaning at equilibrium, all of the alkali will have reacted, so your molar quantities at equilibrium are:

	CH3CH2CH2COOH	NaOH	CH3CH2CH2COONa	H2O
Initial amount	0.0125	0.0025	0	0
Equilibrium amount	0.01	0	0.0025	0.0025

The total volume of your solution is 50cm^3+50cm^3= 100cm^3
Concentration of CH3CH2CH2COOH at eqm= (1000xn)/v=(1000x0.1)/100=0.1 mol dm^-3
Concentration of CH3CH2CH2COONa at eqm= (1000x0.0025)/100= 0.025

Ka=[H+][CH3CH2CH2COO-]
[CH3CH2CH2COOH]

So [H+]= Ka x [CH3CH2CH2COOH]
[CH3CH2CH2COO-]
=(1.51 x 10^-5)
0.025
=0.0000604, and pH= -log[H+] so pH= 4.218963061= 4.22

Hope this helps!

---

Unit 4 is out of 75

Hi guys, I have such issues with chemistry, I understand it but when it comes to revision the content refuses to stay in my head :(
Do you have any advice please, I'm dreading my unit 1 retake and my unit 2 exam.

Done most of the unit, bar a few minor things like polymerisation (seems okay) and the stuff about mass spectra/infra red etc. Done the alcohols and extraction of metal on my own during these holidays. Good to do that so I can see if there are any differences in my notes and the teachers'.

Thanks, do you know if they change much from year to year?
Our cohort seems to be really smart, so I hope they don't go up too much :P


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The new specification is the new set of A-Levels that were introduced in the summer of 2008. This means people were able to take the "New" AS Level exams in 2009 and in 2010 they were the first people to be awarded A-Levels in the new system. There is not much difference between the new and the old specification, the main difference is that some of the theory has been changed around between modules and it is now possible to be awarded an A* in the A-Level as before it was not.

• Firsty if you are going to buy a chemistry mark scheme from the WJEC buy the New Specification ones
• Secondly, do not buy any PM me and I will give you all the ones you want.

You can always tell the difference between a new specification paper and an old one. On the top of the papers there is a code. The new ones start with 1097 and the old ones start with 338.[/QUOTE
dont worry if not , but is it possinble to have some marking schemes please

I looked at it again yesterday, and I'm not entirely sure myself! I think it's because there were two moles of I- in the equation, so it would be used up at double the rate... Or something...

Yeah I agree, well, it was probably alright if you understood it, but I never really learnt that topic properly in the first place :p Exam pressure's a bitch haha.

Ooh that's a lotta chemistry, fun times It's not too bad I guess, just loads of reaction mechanisms and equations etc. to remember! And the fact that the paper is mainly synoptic is pretty scary!

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Hi all,
I was wondering if anyone could advise me on the maths type questions often worth about 5-7 marks in the F325 papers. I have only done the jan 2013 paper so far and lost the majority of marks on the 7 marker at the end and other maths-style questions. I just don't know how to approach what the question is trying to ask, end up working out moles and not knowing what on earth to do with them! Has anyone got any hard questions related to the ones I refer to n the jan 2013 paper, or any advice on how to approach them? Really need an A on this exam, s any advice would be much appreciated.

Sick of schools cheating on isas, its really not fair on the people who try hard revising for the exam only for the grade boundaries to be stupidly high because of cheating, good luck cheating in the june exams :P.

Yes, like I said before, the Round 2 paper is set with relative difficulty of what the International paper will be like.

Well done on your gold. I think my extra reading for Oxford helped a lot; reading Why Chemical Reactions Happen and Chemistry3 certainly helped in the few more difficult topics on both Round 1 and Round 2. As you'll know, there's a general chemistry knowledge round too so having a broad range of knowledge on chemistry from whatever sources is always going to be handy! :)

Never help someone on an empa! Why would u go through hard work revising n then help cheaters,making the boundaries go up? It's insane

I think it might be about nanoparticles or an evalutating question

Anyone? I've got it tomorrow!!

Can anybody tell me why you had to leave the cruicible to cool in the 1st task? there must be a reason as to why........

Everyone wish you all luck. Every one will be fine.
GOOD LUCK!!! :):):)

hi guys, can someone post a thread of the specimen paper for c3 and c2 that is linked to my exam in may. please reply! im quite stressed out at the moment!
much appreciated!

Unit 1 and 2 :)

I'm not quite sure about your method but this is how i work out empirical formula:

first divide evrything by Ar

Carbon = 66.63/12 = 5.5525

Hydrogen= 11.18/1 = 11.18

Oxygen= 22.19/16 = 1.3868

Now divide each of these values by the smallest one to get a ratio (ie 1.386)

Carbon= 5.5525/1.3868 = 4

Hydrogen= 11.18/1.3868=10

Oxygen= 1.3868/1.3868= 1

So the empirical formula must be C4H10O

Edit: also the reason why it does not add up to 72 and to 74 is most likely an error, in writting the question, or may be due to the experimental nature of the results???

Hahaa thankyou :p nearly gone crazy revising it ALL THE TIME.

Going through the book, loads and loads of past papers!

Hey guys I'm new to student forum but you guys all seem super helpful!
Just wondered if anyone has a copy (official or unofficial) of the jan 2013 chemistry unit 2 exam? I'd be more than grateful for any assistance!
Thanks a lot in advance!

Yes do u have any tips

Remember as well, the issues discussed in Unit 2 about fuels, concern everyday members of the public, therefore moles would be confusing to them, but mass given off, or volume given off, gives a clear cut about which fuel has more of a greenhouse effect on the environment. It's sounds silly me saying this because after all, it is a chemistry paper we're doing, but these topics concern everyone, not just people who study/take an interest in chemistry.

:)

i'm currently doing this controlled assessment, and for the factors that could be investigated i've put concentration of acid/alkali, volume of acid/alkali, strength of acid (talk about how it gives away protons) - i've chosen volume, as i think it'll be easier to speak about how the more particles means more bonds etc. apparatus list is like sodium hydroxide and hydrochloric acid (they're the acids/alkali's i'm using), a beaker, thermometer,measuring cylinder and stopwatch. hope that's helped a bit:)

Hello, Do you please remember the questions?
I have mine tomorrow.

Thank you.

They have these PowerPoints which I think they got from a website basically every as to a2 topic in the aqa syllabus, I will try this week inshaAllah to upload them or maybe via email or something

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I have an A2 chemistry practical about chromium. I have been advised to revise transition metals and about oxidation of ketones and aldehydes. Has anyone doing the OCR A2 syllabus completes this task and if yea could you please give me a few hints on what else to revise. My practical grade at the moment is a D I really need to boost my grade.

Thank you

How did you find it? I have this tomorrow- any tips?

Just don't mess up your real one. This is only a practise, so I doubt you're going to get the same volumes in the real thing. The best thing to do is ask for tips on doing the titration instead of this.

Hello,
I am not asking someone for the answers, I just need some help in all the moles questions. Please pm me if you're free it would mean alot to me I am horrible in moles and I do not want to fail this.
Ive done every single isa from both in biology and physics and this is my last in chem. Please pm, I just dont want to mess this one up thankyou :)

If the maximum UMS is 320 (which is strange number), you'd need 288 or above to get an A*. Also be careful that you don't mix up UMS and raw mark. The mark you get on your paper isn't the same as the UMS.

Hello, do you do A2 chemistry?

That's what I'm on at the moment in my coursework, though there's one more evaluative available to do, with the possibility of getting another 5 marks. You've inspired me, thanks.

I've got my final quantitative tomorrow and its on hydrogen peroxide with a catalyst? Any tips from anyone :)


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I have my AS Qual (qualitative) 3 coursework tomorrow for chemistry OCR, and the information i've been giver is:
1. You will attempt to identify unknown solutions;
2. You will investigate reactions of a Group 2 compound.
I need to maximise my marks in this so any help or tips would be really appreciated.
Thanks!!

Has anyone done this? Help much appreciated. I've done the quantitative and evaluative so let's help each other out :D

jan 2013 question papers from :- http://www.freeexampapers.com/
Dunno about mark schemes...