Edexcel Chemistry A2 Unit 5 ~ Wednesday 19th June 2013 (Now Closed) Watch

Poll: How pumped up are you for this exam?-(warning)-(bad jokes arene this poll!)
"Titanium-I'm not going to corrode (even at high temperatures)" (A*) (22)
16.67%
"Benzene's my middle name, give me the paper in a week and I'll ace it!" (A) (27)
20.45%
"Yeah, I'm fairly electrophillic (positively charged) about the exam" (B) (27)
20.45%
"I'm in the middle of the salt bridge, but I will pass-eventually" (C) (21)
15.91%
"I'm feeling rather electroNegative about this exam" (D) (18)
13.64%
"Benzene, what's that?" (E) (6)
4.55%
"Chemistry, what's that?" (F) (11)
8.33%
This discussion is closed.
TheNoobyPotato
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Retaking unit 4
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Mollymod
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(Original post by posthumus)
Damn our frickin' teachers ! They're used to students retaking anyway... maybe they're trying to mislead us.

And in general what would you expect ?
How'd you find Unit 4?

And what do you mean, exam content?
(If so, Benzene, Proteins, Transition Metals, big Redox Titration Calculation, the usual really...) Bit of Synoptic thrown in for the fun of it etc.
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posthumus
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(Original post by Mollymod)
How'd you find Unit 4?

And what do you mean, exam content?
(If so, Benzene, Proteins, Transition Metals, big Redox Titration Calculation, the usual really...) Bit of Synoptic thrown in for the fun of it etc.
Oh not so great ! This is why I'm asking lol I got a D which wasn't much of a surprise (U in Chem 2 -__- ). And yourself ?

Oh I also meant like what would you expect like overall difficulty be to obtain a certain grade in June compared to January (including grade boundaries of course).

That being said grade boundaries seem to be so unpredictable recently ! :s
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David Tennant
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(Original post by Warlord)
Doing it again in june or leaving it?
And thats excellent, well done, but you got like nothing wrong haha! I remember you correcting me about the br- order lol, you seemed to have gotten everything correct
That's why I'm puzzled as to what exactly I got wrong! 16 ums is a actually quite a lot of ums so I may consider retaking...or even remarking
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Mollymod
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(Original post by posthumus)
Oh not so great ! This is why I'm asking lol I got a D which wasn't much of a surprise (U in Chem 2 -__- ). And yourself ?

Oh I also meant like what would you expect like overall difficulty be to obtain a certain grade in June compared to January (including grade boundaries of course).

That being said grade boundaries seem to be so unpredictable recently ! :s
Oh but I'm sure your raw mark wasn't that low, as you needed just under 61 to miss out on the C. I don't really think that's fair at all, as you can get well over half the paper right and still get a D, and I had a similar issue. Unit 2 isn't my favourite unit, but I needed to retake it desperately, as it was my U last year. Now, it's Unit 1 dragging everything down. Unit 2 worked with Unit 4 so it wasn't too bad to revise, but Unit 1 isn't my favourite unit at all. I think it branches over too much with physics and Maths for my liking, and as a Y12 who hated maths, it just wasn't the one for me! I got B's in units 2 and 4 this time round.

It's really unpredictable, but I'd assume that hopefully the paper would be a similar difficulty to the one we had (if not, slightly easier) with probably the same, if not similar boundaries to January. This was the case with January 2012 and June 2012 I think. I'd done both papers, finding both okay with January having the higher boundaries.

(Original post by David Tennant)
That's why I'm puzzled as to what exactly I got wrong! 16 ums is a actually quite a lot of ums so I may consider retaking...or even remarking
My marks were capped at 2/5 on the Br- question :P Good enough for me, but thanks for all the corrections! 7/7 on the NMR but a low-ish multiple choice. Doesn't your teacher give you the spreadsheet/printout of exactly where you picked up your marks? Then you could analyse your paper properly and see where you lost your couple of marks. For some reason, Edexcel show this to teachers, but students don't have access to it
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-strawberry-
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I find this unit so so so hard. My teacher doesn't teach - she makes us read the book in lessons and then make notes at home. I'm finding it so difficult and I need a B over all I'm currently two marks off a B at AS can anyone help me?
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shumen9523
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(Original post by -strawberry-)
I find this unit so so so hard. My teacher doesn't teach - she makes us read the book in lessons and then make notes at home. I'm finding it so difficult and I need a B over all I'm currently two marks off a B at AS can anyone help me?
Hey, if you have any questions about this unit or if you're struggling with somehing, just post your questions on this thread.
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David Tennant
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(Original post by -strawberry-)
I find this unit so so so hard. My teacher doesn't teach - she makes us read the book in lessons and then make notes at home. I'm finding it so difficult and I need a B over all I'm currently two marks off a B at AS can anyone help me?
(Original post by shumen9523)
Hey, if you have any questions about this unit or if you're struggling with somehing, just post your questions on this thread.
Yeah feel free to ask anything!
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-strawberry-
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(Original post by shumen9523)
Hey, if you have any questions about this unit or if you're struggling with somehing, just post your questions on this thread.

(Original post by David Tennant)
Yeah feel free to ask anything!
Thank you both of you I do have a question but I'm not at home at the moment so I'll probably ask tomorrow
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posthumus
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(Original post by Mollymod)
Oh but I'm sure your raw mark wasn't that low, as you needed just under 61 to miss out on the C. I don't really think that's fair at all, as you can get well over half the paper right and still get a D, and I had a similar issue. Unit 2 isn't my favourite unit, but I needed to retake it desperately, as it was my U last year. Now, it's Unit 1 dragging everything down. Unit 2 worked with Unit 4 so it wasn't too bad to revise, but Unit 1 isn't my favourite unit at all. I think it branches over too much with physics and Maths for my liking, and as a Y12 who hated maths, it just wasn't the one for me! I got B's in units 2 and 4 this time round.

It's really unpredictable, but I'd assume that hopefully the paper would be a similar difficulty to the one we had (if not, slightly easier) with probably the same, if not similar boundaries to January. This was the case with January 2012 and June 2012 I think. I'd done both papers, finding both okay with January having the higher boundaries.
Woww, well done ! I am aiming for a B too... And I put all my time and energy into Chemistry and still I've now ended up entered in for all 4 unit exams to do in the space of a month

Any tips on how to revise for so many exams? In January I wanted to do so well in unit 4 that I decided to basically sleep through by unit 2 retake (hence the U )... yet still got a D So I'm not at all good at prioritising! :/

I would love for me to like somehow join both george facer books (A2 & AS) and revise for all units together seamlessly
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Mollymod
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(Original post by posthumus)
Woww, well done ! I am aiming for a B too... And I put all my time and energy into Chemistry and still I've now ended up entered in for all 4 unit exams to do in the space of a month

Any tips on how to revise for so many exams? In January I wanted to do so well in unit 4 that I decided to basically sleep through by unit 2 retake (hence the U )... yet still got a D So I'm not at all good at prioritising! :/

I would love for me to like somehow join both george facer books (A2 & AS) and revise for all units together seamlessly
I know exactly what you mean. I got a D in Unit 1 and a U in Unit 2 initially. I retook the U as it was the most urgent exam in need of attention. Unit 2 works very well with Unit 4 as some of the topics are very similar, such as kinetics, equilibria, rates of reaction etc. Essentially, I think of Chemistry as a long story really. Each chapter follows on from each other like a big progressive book. I learn things by learning all the organic all at once, as in the reaction schemes, and functional group tests and all precipitates formed. Then, I had a look at the mechanisms which help me understand how the end products from each reaction are formed. I'm going to do Unit 1, as I did unexpectedly well in Units 4 and 2. I didn't really want to touch Unit 1 again because it's one of the most dull units for me, but it has to be done. Try to group the bits of Chemistry that you find difficult and focus most of your attention on those. Then, brush up on your stronger parts to make sure everything's still cool with those, but it's all too easy to practice the things you like thinking you're being productive. I'm 90 UMS off a B overall, and I don't want to leave all of that on Unit 5.

I think it's good to pair up what goes with with each topic. For example, learning Unit 2 equilibria at the same time as learning Unit 4 Equilibria will make sure you know all the equilibria you have to know. It helps because they're the same topic but just knowledge is built-on. Then, try to do the same for rates and kinetics. Have a model Unit 2 answer, and a model Unit 4 answer ready. I have a lot of resources on these things that you can just ask for It's all just practice. I have a couple more assessed practicals to do next week. Hopefully will score higher on those How are they for you?
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posthumus
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(Original post by Mollymod)
I know exactly what you mean. I got a D in Unit 1 and a U in Unit 2 initially. I retook the U as it was the most urgent exam in need of attention. Unit 2 works very well with Unit 4 as some of the topics are very similar, such as kinetics, equilibria, rates of reaction etc. Essentially, I think of Chemistry as a long story really. Each chapter follows on from each other like a big progressive book. I learn things by learning all the organic all at once, as in the reaction schemes, and functional group tests and all precipitates formed. Then, I had a look at the mechanisms which help me understand how the end products from each reaction are formed. I'm going to do Unit 1, as I did unexpectedly well in Units 4 and 2. I didn't really want to touch Unit 1 again because it's one of the most dull units for me, but it has to be done. Try to group the bits of Chemistry that you find difficult and focus most of your attention on those. Then, brush up on your stronger parts to make sure everything's still cool with those, but it's all too easy to practice the things you like thinking you're being productive. I'm 90 UMS off a B overall, and I don't want to leave all of that on Unit 5.

I think it's good to pair up what goes with with each topic. For example, learning Unit 2 equilibria at the same time as learning Unit 4 Equilibria will make sure you know all the equilibria you have to know. It helps because they're the same topic but just knowledge is built-on. Then, try to do the same for rates and kinetics. Have a model Unit 2 answer, and a model Unit 4 answer ready. I have a lot of resources on these things that you can just ask for It's all just practice. I have a couple more assessed practicals to do next week. Hopefully will score higher on those How are they for you?
Wow that's surprising since you seem so good at chemistry ! :O (from unit 4 thread). I struggle pathetically... I got B in Unit 1 then after that D in Unit 2 & now D in unit 4 as well I can't seem to get the grades up....

I did an insane amount of unit 4 non-stop for 3 weeks, neglecting my other exams! I went off topic a lot too and learnt some things from outside the syllabus, do you think the George Facer book can be too unnecessary at times ? And I should study through it briefly.. ?

And yh that sounds good to me It was all the group 7, group 2 stuff that I was really clueless about. Redox stuff also, which I think is in unit 5 ?

I didn't do too well in Practical assessment last year (school not allowing us to retake), I got 36/60 in unit 3 which is on boarder line of C/D.
I've done exceptionally well this time round in unit 6. I've got 14/14, 13/14 as my 2 best grades... and we have final one to do which is observation & doing it this Monday
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Weaselmoose
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Hey guys, lots of friendly faces from the unit 4 thread here... How was it?
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Mollymod
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(Original post by posthumus)
Wow that's surprising since you seem so good at chemistry ! :O (from unit 4 thread). I struggle pathetically... I got B in Unit 1 then after that D in Unit 2 & now D in unit 4 as well I can't seem to get the grades up....
I'm only getting better really, through practice and practice, more practice and not being too scared to ask more questions. You're far from pathetic. I really admire anyone trudging through A2 Chemistry, because it is a hard subject. A B is very commendable and it's entirely understandable to get a D and U. Whatever you get, someone has always gotten worse. It sounds like a horrible and silly thing to think, especially as you want to do better for yourself and ultimately nobody else matters in terms of your exams, but the truth is, they do. Boundaries are set on how well everyone else does, and what you're struggling with; chances are, someone else in the country struggles with the same thing too. Difference is, you aren't giving up even though it's easy to, and that's what counts. Unit 1's the foundation, so it's good you've got that solid. Taking units 2 and 4 together will be good for you, and you have a few months yet to get them up It's hard, so don't feel discouraged. I'm basically the same as you but switched over. Got a D in Unit 1 and now a B in unit 2 so you can do it if you made it to A2 So what are you on now in total, a D?

(Original post by posthumus)
I did an insane amount of unit 4 non-stop for 3 weeks, neglecting my other exams! I went off topic a lot too and learnt some things from outside the syllabus, do you think the George Facer book can be too unnecessary at times ? And I should study through it briefly.. ?
It's all a balancing act George Facer's book is very unnecessary, but the things it does explain, it explains very well, as well as the examiner tips and hints. Try not to read the introductory pages especially in the AS book as it's irrelevant. Look at the practical tips and try to skim over the things you do know, as to have enough time to browse properly over the things you don't know. I didn't spend too much time on Unit 2 organic because organic is my strength. My weakness is inorganic, so I spent a bit of extra time looking at Redox, Titrations, Decomposition of Nitrates and Carbonates and Green Chemistry. Only work when you have enough time, and energy to. Otherwise it'll just go in one ear, out the other. Try a range of things as well. I made Powerpoint slides and put everything about each topic on each slide. It's a bit congested for some, but for me, it worked a treat because I like to see everything at once and condensed.

(Original post by posthumus)
And yh that sounds good to me It was all the group 7, group 2 stuff that I was really clueless about. Redox stuff also, which I think is in unit 5 ?
Yeah, and that can drop you down a hell of a lot because it will always come up. It's just stuff you've got to learn unfortunately. Really dull, and I had a bad teacher for that initially, hence my weakness in inorganic. We were never told what to actually learn in terms of trends, so that really tripped me up the first sitting. I wouldn't have done much better had I known all of that anyway. Yeah, with Unit 5, you should be a lot more confident on Redox eventually Are you alright on Bond Angles?

(Original post by posthumus)
I didn't do too well in Practical assessment last year (school not allowing us to retake), I got 36/60 in unit 3 which is on boarder line of C/D.
I've done exceptionally well this time round in unit 6. I've got 14/14, 13/14 as my 2 best grades... and we have final one to do which is observation & doing it this Monday
Ooh nice about your Unit 6. I got 41/60 at AS which is a high C I think. School doesn't let me retake AS practicals either which is a bit of a bummer, because I could do a bit better this time round. I'd have to do a hell of a lot of practicals though if I retook, as you need all B, C and D skills from AS to submit together apparently. At the moment, I've got 13/14, 11/14 and 10/12 which totals to 34/40 which would be converted to 43/60 so it's a low B. Seeing if I can improve that next week, as a B would be great overall.

(Original post by Weaselmoose)
Hey guys, lots of friendly faces from the unit 4 thread here... How was it?
Surprisingly well, got a B, and you?
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F1's Finest
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ffs got worse in unit 5 than last time! takes the piss!

80/120 I am so annoyed! :rant: defo getting my paper back.
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jojo1995
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(Original post by James A)
ffs got worse in unit 5 than last time! takes the piss!

80/120 I am so annoyed! :rant: defo getting my paper back.

sorry to hear ... there is always june and apparantly it was a dodgy paper ... dont be angry - breathe
did you just get your results today ?
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F1's Finest
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(Original post by jojo1995)
sorry to hear ... there is always june and apparantly it was a dodgy paper ... dont be angry - breathe
did you just get your results today ?
thanks

yeah, I can't understand, but the paper I'll get back should clear up some issues.
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LeaX
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Really struggling with redox titration calculations using reducing agents (I2 and thiosulphate).

Could anyone please help me with this question:
A sample of Admiralty Brass of mass 3.00 g was treated with nitric acid and made up to a neutral solution of volume 250 cm3. Excess potassium iodide was added to 25.0 cm3 portions of this solution, and the liberated iodine was titrated with sodium thiosulfate solution, concentration 0.100 mol dm–3. The mean titre was 33.10 cm3.

The equation for the reaction between copper(II) ions and iodide ions is shown
below.
2Cu2+ + 4I–→ 2CuI + I2
Hence calculate the percentage by mass of copper in Admiralty Brass. Give your answer to three significant figures.


Mark scheme:
Spoiler:
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Amount thiosulphate
= 0.0331 dm3
x 0.1 mol dm —3
= 0.00331 mol (1)
= amount of copper(II) ions in 25 cm3
portion
(1)
∴ amount Cu = 10 x 0.00331= 0.0331 mol in
total (1)
∴ mass Cu = 0.0331 mol x 63.5 g mol-1 (1)
= 2.102 g
∴ % copper = (2.102 x 100)÷ 3.00 (1)
= 70.1% (1) to 3 s.f. only


I don't understand how to do this. I understand you get the ratios which give you 2 moles S203: 1 mole I2
But then I thought the ratios of I- and Cu2+ were 2:1
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shumen9523
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(Original post by LeaX)
Really struggling with redox titration calculations using reducing agents (I2 and thiosulphate).

Could anyone please help me with this question:
A sample of Admiralty Brass of mass 3.00 g was treated with nitric acid and made up to a neutral solution of volume 250 cm3. Excess potassium iodide was added to 25.0 cm3 portions of this solution, and the liberated iodine was titrated with sodium thiosulfate solution, concentration 0.100 mol dm–3. The mean titre was 33.10 cm3.

The equation for the reaction between copper(II) ions and iodide ions is shown
below.
2Cu2+ + 4I–→ 2CuI + I2
Hence calculate the percentage by mass of copper in Admiralty Brass. Give your answer to three significant figures.


Mark scheme:
Spoiler:
Show
Amount thiosulphate
= 0.0331 dm3
x 0.1 mol dm —3
= 0.00331 mol (1)
= amount of copper(II) ions in 25 cm3
portion
(1)
∴ amount Cu = 10 x 0.00331= 0.0331 mol in
total (1)
∴ mass Cu = 0.0331 mol x 63.5 g mol-1 (1)
= 2.102 g
∴ % copper = (2.102 x 100)÷ 3.00 (1)
= 70.1% (1) to 3 s.f. only


I don't understand how to do this. I understand you get the ratios which give you 2 moles S203: 1 mole I2
But then I thought the ratios of I- and Cu2+ were 2:1
Hey there,
I2 + 2S2O3^2- --------> S4O6^2- + 2I-
2Cu2+ + 4I- ---------> 2CuI + I2
it's true that 2 moles of S2O3 give 1 mole of I2. However, remember that according to the second equation, 1 mole of I2 is produced from 2 moles of Cu2+. In other words:
2 S2O3 --------------> 1 I2
and 2 Cu2+ -------------> 1 I2
we are not really concerned with the I- ions as it is the I2 that links the two equations together not the I-.
Hence, you can find the numbers of I2 by dividing 0.00331 mol by 2 to get 0.00155 mol. You would then have to multiply this by 2 to get the number of moles of Cu2+ ions in the 25cm^3 . So 0.00155 * 2 = 0.00331. this means the number of moles of S2O3 is the same as the number of moles Cu2+. In the mark scheme, this step isn't mentioned which is why the answer might seem to be confusing at first. Hope this helped.
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David Tennant
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(Original post by Weaselmoose)
Hey guys, lots of friendly faces from the unit 4 thread here... How was it?
Hey Weasel, it wasn't too bad I managed to improve my unit 2 result and I got a reasonable score on my unit 4. How did it go for you though?
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