[steelbird524]

Hi, I'm confused on this problem and was wondering if someone can help me out.

H2 + I2 <------> 2HI

Keq = 55.64

the following reaction has been determined at 698K. .1 moles of H2 and I2 and .5 moles of HI are placed in a 5 L flash at 698K.  Find the initial pressure of each gas.  Find the equilibrium pressure of each gas.

I was wondering if I need to use the Ideal gas law to solve this problem.  and if someone can help me set this problem up that would be great.  thanks

[Albert]

I was wondering if I need to use the Ideal gas law to solve this problem.

Yes, go on: you'll find the initial partial pressure of each gas.

[SoFTiCE]

K=[HJ]2/[H2]*[J2]
[H2]=0.02-X=[J2]
[HJ]=0.1+X
We have
55.64=(0.1+x)^2/(0.02-x)^2
0.1+x/(0.02-x)=7.46
0.1+x=7.46*.02-7.46x
0.49=8.46x
x=0.0058
[HJ]=0.1058M
[H2]=[J2]=0.1942