Assume that gaseous hydrogen iodide is synthesized from hydrogen gas and iodide vapor at 50 degrees celcius where the equilibrium constant is 1.00 x 10^2. Suppose HI at 5.00 10^-1 M, H2 at 1.00 x 10^-2 M, and I2 at 5.00 x 10^-3 M are mixed in a 5.0 L container. Calculate all concentrations at equilibruim.

Answer 1

I have made an assumption that the numbers listed at the beginning of the experiment, are in fact, molarity and not moles.
H2 + I2 ==> 2HI

Set up ICE chart, substitute into Keq expression, and solve for x, then calculate the concn of each component.
You may want to calculate Qeq first (I obtained 5,000 for that) which tells us that HI is too high, the others are too low; therefore, the reaction must move to the left.
initial concn:
H2 = 0.01 M
I2 = 0.005 M
HI = 0.5 M

change in concn:
H2 = +x
I2 = +x
HI = -2x

equilibrium concn:
H2 = 0.01+x
I2 = 0.005+x
HI = 0.5-2x
By the way, note the correct spelling of celsius.

Answer 2

This problem shifts right by definiition of a Kp that is > 1