Chemical Equilibrium?

MaggieNF

can anyone explain how to do the 2008 higher level equilibrium question


just the piece about calculating the kc

"

A chemical equilibrium is established when eleven moles of hydrogen and eleven moles of iodine are mixed at a temperature of 764 K. Initially the colour of the mixture is deep purple due to the high concentration of iodine vapour. The purple colour fades and when equilibrium is established the colour of the mixture is pale pink and there are seventeen moles of hydrogen iodide present.
The equilibrium is represented by the equation

H2 (g) + I2 (g) -> 2HI (g) ΔH = 51.8 kJ
colourless purple colourless

(b) Write an expression for the equilibrium constant (Kc) for the reaction.

Calculate the value of the equilibrium constant (Kc) at 764 K."


Cheers

zam

H2 + I2 = 2HI
(11) + (11) = (0)
(x) + (x) = (17)
17 moles added to HI but becuase it's 2HI, 8.5 per one
(11-8.5) + (11-8.5) = (17)
(2.5) + (2.5) = (17)

(17^2)/(2.5*2.5) = 46.24

leg

kc = U]HI[/U²
[H2][I2]

H2 + I2 = 2HI

11M 11M 0M

2.5 2.5 17

[17]²
[2.5][2.5] = 51.8

Then finish as normal

MaggieNF

zam wrote: »

H2 + I2 = 2HI
(11) + (11) = (0)
(x) + (x) = (17)
17 moles added to HI but becuase it's 2HI, 8.5 per one
(11-8.5) + (11-8.5) = (17)
(2.5) + (2.5) = (17)

(17^2)/(2.5*2.5) = 46.24

this may sound silly but how do you know that the 2HI is 17, i know its 2 x 8.5, but why 8.5?

zam

MaggieNF wrote: »

this may sound silly but how do you know that the 2HI is 17, i know its 2 x 8.5, but why 8.5?

It says its 17m at equilibrium in the question! So seeing as it's 2HI, you divide 17 by 2 to get your 8.5

MaggieNF

i just saw that, god I'm silly...


gonna do fair good tuesday NOT!!!

zam

MaggieNF wrote: »

i just saw that, god I'm silly...


gonna do fair good tuesday NOT!!!

Haha well at least you're studying!! More than I can say for me...

MaggieNF

LOL, i do try but not doing very well...... **** chemistry your last?

zam

MaggieNF wrote: »

LOL, i do try but not doing very well...... **** chemistry your last?

Yes! You? Thank god!

MaggieNF

zam wrote: »

Yes! You? Thank god!

same, do ya feel like you just don't care about this exam?!?!?!

Captain-America

MaggieNF wrote: »

same, do ya feel like you just don't care about this exam?!?!?!

I feel like that. I really need it for points too. Gonna study like a motherfúcker tomorrow.

zam

MaggieNF wrote: »

same, do ya feel like you just don't care about this exam?!?!?!

Yes! It feels like it's summer already. Only a matter of a day and a half!

MaggieNF

Captain-America wrote: »

I feel like that. I really need it for points too. Gonna study like a motherfúcker tomorrow.

ahhhh bless...

zam wrote: »

Yes! It feels like it's summer already. Only a matter of a day and a half!

i thought that too! i said i would study in the sun..pffft yeah right!!!

none of us will study

FordieMUFC

zam wrote: »

H2 + I2 = 2HI
(11) + (11) = (0)
(x) + (x) = (17)
17 moles added to HI but becuase it's 2HI, 8.5 per one
(11-8.5) + (11-8.5) = (17)
(2.5) + (2.5) = (17)

(17^2)/(2.5*2.5) = 46.24

This.
I would have recommended a book to you all but forgot, sorry
unless you're minted and will still buy it tomorrow, it's called Exam Edge by folens, has all questions by topic and solutions. It's handy out.