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

Yep. Solid - liquid Entropy increases. Energy is needed to break the bonds in the lattice (ice) so energy needs to be put in so delta H is +

Thanks. Thought so

Reply 2941

Jtking3000

13

Original post by jontylol

Really?! I may have a chance at the A* yet! :biggrin:

jan 2011 had 65/100 for an A with 7/8 mark increments so presumably that meant 73 for an 90% ums. if this paper is so much harder than jan 2011 like everyone says it is then it might even be slightly lower.

Reply 2942

MattyEFC

That paper was truly insane.
Why on earth would they include a question on sweets? The Battery question threw me as well. The rest was relatively okay.
Am I right in assuming that any acid would get you the mark for that Buffer question, along with any valid concentrations as the paper gave you no guidance?

Reply 2943

samzurai

not looking forward to results day....

Reply 2944

123trident

I need a low B to get an A overall, what do you guys think will be the grade boudanry for a B? Does 57-60 for a B sound fair?

Reply 2945

*QueenBeee

please please can someone help me!!
what was the answer to the KOH electrolyte question??
where we were given two pka values and we had to write equations??
what did everyone put?!
xx
major rep for life!

Reply 2946

wilsea05

1

+ 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

Reply 2947

sc0307

8

Was anyone's initial rate 4.44x10-5 and k 4.44x10-3 ??

Reply 2948

CitizensUnited

1

On the bipy one, I'm fairly sure that the N atoms were on opposite sides of the ring to the C-C bond...

I got stuck on Q1 :colondollar:

Reply 2949

sc0307

8

Original post by *QueenBeee

please please can someone help me!!
what was the answer to the KOH electrolyte question??
where we were given two pka values and we had to write equations??
what did everyone put?!
xx
major rep for life!

I think with the 2 pKa values they gave you...you had to write the equation that dissociated both the H+ ions i.e -OOCCOO- next to the lower pKa value and write the equation that dissociated one of the H+ ions i.e HOOCCOO- next to the higher pKa value.

Reply 2950

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!

Reply 2951

RodrigoB

4

Original post by sc0307

Was anyone's initial rate 4.44x10-5 and k 4.44x10-3 ??

mine mate!!!
It did exactly like it is shown on the edexcel book.

Initial rate = 0.01/(+ or - 225)

we are prob right :biggrin:

Reply 2952

sc0307

8

Original post by RodrigoB

mine mate!!!
It did exactly like it is shown on the edexcel book.

Initial rate = 0.01/(+ or - 225)

we are prob right :biggrin:

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

Reply 2953

wilsea05

1

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

there will be a range between what they accept. i had (0.01-0.0065)/100 so my answer for initial rate was 3.5x10^-5

Reply 2954

Masderchef

1

Original post by wilsea05

+ 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

Are you sure the mark allocations are correct for the rate constant question
and the boxer ticker on entropy?

Reply 2955

sportycricketer

Original post by wilsea05

there will be a range between what they accept. i had (0.01-0.0065)/100 so my answer for initial rate was 3.5x10^-5

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