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

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+ REP anyone? :wink:

i've had nothing at all to do tonight haha.

questions, marks, and the answers. (some of them are just my attempt at it, e.g. the decomposition of KOH, and i'm also not 100% about the marks for each question but i've made it =100 so 1 question maybe +/- 1mark than its actually worth)

http://www.mediafire.com/?g779xf52up4b79p

for the 3d polymer Question, if it wants one repeat unit, would it just be one nickel complex ion/ligand thingy and the 4,4 bidy group, not two ligands and a 4,4bidy group thing? Just outta interest?!

(edited 12 years ago)

Reply 2961

bambinooo

Original post by bambinooo

would i get a few marks for putting lactic acid and writing out the equations for salt and conjugate base?

also what did people put for the koh question?

i put

2KOH + 2e- -----> H2 + 2KO

also strength of acid : extend of dissociation of h+ ions and i put down equations!

someone please answer its bugging me :frown:

Reply 2962

wilsea05

Original post by bambinooo

someone please answer its bugging me :frown:

i put that equation for it too, along with 2KOH +2e -> O2 + 2KH cus it asked for the equations at each electrode, and one produced O2 and one produced H2.

and yeah strength of acid - ability to donate or lose H+ is what i put

Reply 2963

Nbear

i ignored K because I thought that it was a spectator ion :s-smilie:

Reply 2964

Dpax2max

all of this is pointless if neither of you lot have sent an email. 3 in my area have .. so come on people !! already know around 40 people that sent it. Imagine being OCR and receiving 40 emails with a subject "CHEM F325... ect

Reply 2965

sportycricketer

Original post by sc0307

for ur k?

cant remember exactly but something like 4 x 10^-5

Reply 2966

JakeChocz

Original post by Bullit

Discuss how hard you found it, fair enough. Write complaints to the exam board complaining how it is poorly made and had questions impossible to answer? No. If you did **** in the exam face the facts and accept that it is you own fault, not the exam boards fault for giving you questions beyond your own ability.
Up my own arse? Grow up. I never said the test was easy, all I said was for people to stop complaining to OCR because it ruins the efforts of people trying to get something done about the Biology paper, which was written unfairly.
I then recieve replies from people like you posting insults because you can't handle it. At the end of the day, people will recieve the grade they deserve in this exam. Cry me a river.

I didn't even find the exam that bad, your comment just made you sound like a ****

Reply 2967

RodrigoB

Original post by sc0307

Yay!!!!!!! I worked out mine differently cos I made my tangent slightly smaller (0.01-0.006/90-0) but at least our answers are the same and hopefully right :-D

your tangent was pretty smaller compared to mine then
but we still got the same answer LOL WEIRD
HIGH FIVE! ON THE 8 MARKER ?

Reply 2968

Bullit

Original post by JakeChocz

I didn't even find the exam that bad, your comment just made you sound like a ****

How about you read the context of my comment and what comment it was in reply to rather than trying to act like the big man.

Reply 2969

apo1324

Original post by wilsea05

+ REP anyone? :wink:

When calculating the enthalpy change of hydration wouldn't it be the -lattice enthalpy add all of the other enthalpy changes?

As clockwise enthalpy changes = anticlockwise enthalpy changes? :L BTW the enthalpy change of hydration is always exothermic isn't it?

(edited 12 years ago)

Reply 2970

PinkFriday

Original post by Vitupero

You do realise that the main bulk of your argument will have no affect. OCR states that the exam is more focused on your understanding and your knowledge of chemistry rather than just recalling information. The only part of your argument that you can legitimately argue upon is the time limit, an extra 15 mins and the paper would have been a lot less rushed.

I'm not the person you quoted but if the grade boundaries set for the exam are usually around the 80% mark for AS, and an average of 20% of people are getting over this, why all of a sudden does the grade boundary for an A become 63% (such as in the january 2011 paper). Surely if only 20% of people are getting over 63% then the paper is too difficult. It's all too subjective to say "The paper was too hard" but when put into figures like this, even someone who didn't sit the paper could say it was too hard, and that the questions need to reflect the ability of pupils sitting the exam.
Ofcourse the questions should be harder than simple recall ones, but even the chemistry teachers in my department at college who had commented the AS exams were reasonable, had mentioned the summer one this month was too difficult. OCR seem more bothered about "competing" with other exam boards to see which out of them all can have the most demanding paper; and hence "the best". :rolleyes:

The paper is probably less likely to get a representative and accurate grade to reflect a pupil's ability when the grade boundaries are so close together (like in the January exam) - which is where I think the grade boundaries for this exam will be close to...

(edited 12 years ago)

Reply 2971

wilsea05

Original post by apo1324

thats what ive done? and im pretty sure you wont get a mark for saying 'enthalpy change of hydration is always negative'

Reply 2972

apo1324

Original post by wilsea05

thats what ive done? and im pretty sure you wont get a mark for saying 'enthalpy change of hydration is always negative'

Oh yeah, I see that now. But the answer should be -1921 KJ mol^-1 as it's a negative enthalpy change? So you wouldn't lose a mark if you say its positive?

Reply 2973

wilsea05

Original post by apo1324

Oh yeah, I see that now. But the answer should be -1921 KJ mol^-1 as it's a negative enthalpy change? So you wouldn't lose a mark if you say its positive?

oh my bad, yeah that should be a negative value. i did put it as negative in the exam though :smile:

Reply 2974

inam_ayaz

Original post by joe3469

Nice one dude. All these answers are the same as mine :smile:

pH 2.11 is a strong acid i got around about 4 which makes more sense so i dont know

Reply 2975

inam_ayaz

Original post by BackDoorEntry

i got 4x10^-3 s^-1 using a tangent at t=0

That paper absolutely killed me! Miles harder than both past papers combined, squared, and cubed.

The last question i got 3.4%, i think i left out a 0 somewhere. This is horrible!