Question

At a certain temperature 0.1moles of hydrogen gas and 0.1 moles of iodine gas were placed in 1 litre flask. It was found that the concentration of iodine decreased to 0.02moles per litre. Calculate the value of the Kc for the reaction

Answer 1

initial (H2) = 0.1mol/1 L = 0.1M
initial (I2) = 0.lmol/1 L = 0.1M

......H2 + I2 ==> 2HI
I....0.1...0.1.....0
C....-x....-x......2x
E...0.1-x..0.1-x...2x

So you know I2 at equilibrium is 0.02M which means 0.1-x = 0.02. At equilibrium H2 must be the same. Calculate 2x = (HI).
Plug those values into kc expression and solve for Kc.