MISTAKE IN 2010 CHEM TSFX PAPER

[matt123]

hey guys
i spotted a few mistakes
id appreciate it if someone double checked these for me.

multiple choice 16 is C .. they said B

the first equilibrium question .. thy say the units are M^3 . but its M^2

also Q5B ... part ii...

they said that N(e) = n(mol fe3+) .. but .. it should be

n(mol fe3+) = 1/3(n(e)).

make sense?

can someone please double check the last one.

[Mao]

post question?

[matt123]

post question?

Its in like 5 diff parts .. hard to put up all the info
hold on .. ill try

[jasoN-]

yeah sounds right, pretty stupid on the solutions behalf (assuming these are correct)

on that note, does anyone have a soft copy of the solutions? thanks in adv.

[jasoN-]

oops, for 5bii they are right;
Fe3+ + e -> Fe2+
1 to 1 ratio between Fe3+ and e

[crayolé]

Heres the solutions Jason

And for question 2 - its actually M³ because you cant have concentrations of solids (no M) it's just counted as 1
I thought I had tsfx beat too until my teacher explained it ;P

[matt123]

Heres the solutions Jason

And for question 2 - its actually M³ because you cant have concentrations of solids (no M) it's just counted as 1
I thought I had tsfx beat too until my teacher explained it ;P

True.
but if its just counted as 1.
then the ratio is
1 : 3.
.. hence there is 2 mol MORE on the right side
and so it should be M2

im confused?
unless ur saying .. because its a solid . its counted as 0.

[crayolé]

Well for the concentration fraction to be defined, it technically can't be zero. And you can't have a concentration of a solid so we just assign it a quantity of 1 (not 1M). [i.e The ratio is M³:1]

[matt123]

Well for the concentration fraction to be defined, it technically can't be zero. And you can't have a concentration of a solid so we just assign it a quantity of 1 (not 1M). [i.e The ratio is M³:1]

Ohh kk
sounds good
cheers