The Student Room Group
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>

Equilibria, Energetics and Elements (F325) - June 2011 Exam.

Scroll to see replies

with the buffer question do you reckon they'll give the marks for any acid done correctly as it wasnt specified
Original post by Rickesh
Are OCR trying to kill us ?!!? :frown:


Naa. There just suckin up to the old hags that were too thick in thier days which are constantly saying exams are getting too easy and everyone is getting A*s and bla bla bla.
Original post by sheep_go_baa
If the cathode is the positive terminal and the anaode the negative, then yes.


In a galvanic cell (like this) the cathode is positive and the anode negative, I'm sure there's some good reason for it :smile:
that was pretty hard, im a 3rd year resit and last year i found it hard too, they just throw things that we really havent been taught in there. It specifically says in the spec we only need to know about the first line of the transition metals, and there was an Ru complex in there!

Nasty paper overall. If you got 80 raw i reckon you'll do very well, boundaries in earlier papers have been as low as 65 raw for A.
Reply 2264
Avatar for 786girl
786girl
seriously wth is wrong with OCR ? why is this happening THIS year? don't they realise people's FUTURES are at risk! errghh..this paper cant have differentiated between the best and the worst because I think EVERYONE did ****! :frown:
(edited 12 years ago)
****, i forgot to multiply by 10 in the last question :frown:
Reply 2266
Avatar for ziigmund
ziigmund
Got 66.7% or 67.6% cant remeber exactly for last q, think the latter, not entirely sure my ionic equations were correct though

What did people get for Kc? I got 22.5 mol^-1 dm^3
(edited 12 years ago)
When will someone have the paper up?
Original post by SaturnineDragonfly
It was quite strange, usually there's some obvious thread to pick up to deduce they tell you to, but I also found that in that question there seemed to be no evident reason to choose any of the acids. I chose lactic acid as well, since the sweet has to be edible at least, so it seemed to me that the only two possibilities were lactic and ethanoic, as I doubt it's healthy to eat the acid with benzene in it (can't remember it's actual name) and pyruvic. And out of lactic acid and ethanoic acid, lactic had the lower pKa value, so was a stronger acid (and the pH had to be low, 3.55). That's the only line of reasoning I could think of. Any one else have any other reasoning or figure it out differently for some subtle reason? :confused:

Although, thinking about it, pyruvic is possibly edible? I really don't know.


I also picked Lactic acid but my reasoning was because it's pKa value, of 3.86 I think, was the closest to the desired pH of the buffer (which was 3.55 I think).

I basically remember reading somewhere that the best buffer solutions are produced when the concentrations of the weak acid and it's conjugate base are almost equal and so you wanna have a pKa that's a close as possible, to 3.55 in this case, to achieve this.

Which makes sense because If you think about the henderson-hasselbalch relationship and mess around with it you get the following:

[A-]/[HA]=10^(pH-pka)

so yeah, that's what I got.
Reply 2269
Avatar for susan23
susan23
3
Email: [email protected]

Dear Sir/Madam

I have recently sat the F325 Chemistry A2 exam on the 15th of June 2011. I would like to raise a few concerns on how I personally found the paper.

After having worked so hard for the course of the year and even detrimenting my social life and dedicating the majority of my time to my A2 exams, I am tthoroughly dissappointed at the Chemistry A2 paper that you set us today.

First of all the content of the paper was an overload coincided to the amount of time we had. 105 minutes was not enough time to complete the paper, as well as it consisting of 3-4 essay based questions. Due to lack of time I could not complete 2 of these essay questions. These essay questions definitly required some extra thought as they were not straight forward and I believe if more time was available perhaps the understanding was a little clearer of the so called "Tangy magic sweets," or the massive titration question you were refering to.

In general I find that there is very little material we can practice on as students for these new sylabus exams, and we tend to rely on past papers from the old sylabus of OCR and as much as these are helpful, I find in no way do they contribute to these exams at all.

I understand the whole point of the new sylabus is to introduce a whole new style an logical thinking towards chemistry based questions, but i find this incredibly unfair, due to the lack of relevant material we have to practise on

As well as this, I personally feel that some questions are unrelated to the sylabus at all, which I find unnecessary. In my opnion I find the OCR Chemistry A2 Heinemann textbook to not fully cover all aspects and often be unrelated to some of the questions that are set in the exams. The resources that we have to revise for the new sylabus exams are in no way up to the standard that you expect us to know, considering this also has the new "stretch and challenge" section that was not previously available.

I cannot speak for all students but I find this incredibly upsetting as well as annoying, having put an enourmous amount of effort revising and practising and to realise this was not enough to attempt some of the questions (many of which can be ambiguous) is unfair. I hope you understand that A2 exams are a serious matter to any year 13 student, and that as students we have a life to potentially fulfill and meet the demands of university. As a student who generally achieves top marks, I feel deceived and cheated on after sitting this paper and it was certainly not a valid representation of how much I have learnt through the course of the year. I hope you take whatever I have mentioned into consideration whilst marking this exam, as well as preparation for furture exams, for the future generation.

Yours faithfully,

Susan

Seriously guys, even if you found it good or ok or satisfactory, I think we should all complain because I just find it so unfair how this year getting into university is so important due to the increase in fee rise. Also for Medical and Dental Students its often imposible to apply after retaking in a 3rd year, so if you don't get your grades now, you may never be that doctor or that dentist you have wanted to become for so many years. This also applies to all the other university courses that have increased their grade boundaries such as Biomedical Sciences, Pharmacy, Engineering etc. Often Universitys requite A grades for Chemistry and Engineering as well as Pharmacy and other science based courses. I found this exam just REALLY unfair, and even more unfair that I have no ability to fix it or do anything about it alone. If we do this together as students then we can make a difference. NON of us are ganrateed a university offer yet, and even those who found this exam ok are still susceptiable to low grades, so please make an effort, this could change your furture and fate.

http://www.thestudentroom.co.uk/showthread.php?p=32203386#post32203386
(edited 12 years ago)
Original post by Rickesh
I got 33.8% but I think that's wrong


noooo! dont say that! its right its definitely probably right!
Original post by Unkempt_One
When you start decreasing the difficulty of the papers and increasing the grade boundaries you can get situations where a few silly, generally unavoidable mistakes can cost you a grade. I'm of the opinion that exams should challenge on content rather than grade boundaries. That being said, the current curriculum isn't very good at preparing people for this sort of challenging stuff.

That being said, all the rubbish about the 'magic tang' as well as the hydrogen economy and other things like that, they all need to go.


I don't mind it being challenging, in a January '11 sort of way, where there's a lot of knowledge application but the questions are entirely do-able provided you've worked hard enough. The problem with this paper was that a LOT of questions were very challenging which will push the grade boundaries down, and close together - so a few scribblings could make the difference between grades, equally bad as if they're too high - and there were also a couple of really rubbish questions, especially the industrial large-scale uses of hydrogen, which I have no clue about. I thought the synopticity with the nitrogen dioxide equilibrium question was good, though, as was the long rate one with the conc./time graph and actually I quite liked the ligand/transition element section, even if when you had to draw the polymer section it took far longer than the marks justified in my opinion.
Reply 2272
Avatar for Oink123
Oink123
7
Original post by blush.ox
:facepalm2:

I think i completely ignored the ka/pKa part, and took the conc. to mean a strong acid and that it fully dissociates and then worked out the pH, if that makes sense :banghead:.


That's what I did too, but I wrote a load of other workings out that I thought could possibly be relevant, so I'm hoping I've picked up some marks there.
I have never found an exam this hard. It's the first time I have actually come out of an exam on the verge of crying/feeling sick. There was too much application required in this paper. I think there was an disproportionate amount of longer 5-10 mark harder questions compared to the straight forward 2-3 mark questions, it's no wonder people (including me) ran out of time. Yes, exams should have the element of application of knowledge, but surely only to an extent. With this new syllabus, how the hell could you do any sort of revision for improving your "logical reasoning" skills? Past exam questions did not help at all.

Long story short: my life is over and I have to face yet more OCR tomorrow (Core 4, hurrah).
(edited 12 years ago)
This paper was hard - but not impossible. Its going to define between the people who really know their chemistry and worked very hard to deserve an A star. The buffer question was hard - but then again if they were to give us any other buffer question it would have been far too easy. There was a question like this on one of the old OCR past papers.
Maybe theres point in complaining.. but probably not. I think it should be around 75% for an A, 85% for an A*.
I got some things wrong, I know I definitely lost about 10 marks - the erest will have just been minor errors.
And on the plus side - it was much easier than Biology F215 on Monday!
Did anybody get a KC value of 45?? I deem this one of the easier questions but still, they managed to make ever the simplest of topics within the unit tricky. I can understand you make some things hard and some easier, but literally everything in the paper required more than the average time to think about it. If you have to read so much b****x about 'sweets' and fictitious material then the time allocated should increase. It seems the time taken to read each question has significantly increased, meaning less time to solve them... Does that make sense or am I the only one who believes so??
Reply 2276
Avatar for Oink123
Oink123
7
It wasn't about the paper being difficult, it was the lack of time to do it all in! I don't know about anyone else, but when I feel like I haven't got much time, there's added pressure, more mistakes, lots of rushing and feeling like ****. I mean for the tangy sweets one and the buffer one, I'm usually quite good at those types of questions but the panic of it all sent my brain into **** mode so I couldn't think.
Original post by Unkempt_One
When you start decreasing the difficulty of the papers and increasing the grade boundaries you can get situations where a few silly, generally unavoidable mistakes can cost you a grade. I'm of the opinion that exams should challenge on content rather than grade boundaries. That being said, the current curriculum isn't very good at preparing people for this sort of challenging stuff.

That being said, all the rubbish about the 'magic tang' as well as the hydrogen economy and other things like that, they all need to go.


I agree that the exams should be challenging, OCR is very good at testing our ability to apply our knowledge to new situations - it just seems that the situations they provide are unfairly complex. If they don't change the exam then they certainly need to change the textbook, which is currently full of little errors, and challenge us more while we're learning the course, rather than luring us into a false sense of security before roundhorse kicking us in the face with the exam.
Original post by chemchemchem123
This paper was hard - but not impossible. Its going to define between the people who really know their chemistry and worked very hard to deserve an A star. The buffer question was hard - but then again if they were to give us any other buffer question it would have been far too easy. There was a question like this on one of the old OCR past papers.
Maybe theres point in complaining.. but probably not. I think it should be around 75% for an A, 85% for an A*.
I got some things wrong, I know I definitely lost about 10 marks - the erest will have just been minor errors.
And on the plus side - it was much easier than Biology F215 on Monday!


I's sorry but i worked EXTREMELY hard. Is going through the spec 4 times not enough? Reading every page of the unit at least 5 times not enough? I really sat my ass down this year to get into uni and thanks to OCR im not going to anymore.
when will the paper be up?

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you