Question

A 1.500 Liter vessel is filled with 1.500 moles of hydrogen gas, and 2.500 mol of iodine gas to form hydrogen iodide gas at 448 oC. The reaction has an equilibrium constant of 53.5. What is the equilibrium molar concentration of all species?

Answer 1

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

t=0         1.5                2.5

t=eq       1.5-x              2.5-x                    2x

K = 53.5   = [HI]²/[H₂][I₂] = (2x)² /(1.5-x)(2.5-x) =

on solving the quadratic equation :

    x   =   1.37  

[HI] = 2x/1.5 = (2x1.37)/1.5 = 1.826 M

[H₂] =   (1.5-x)/1.5 = (1.5-1.37)/1.5 =0.086 M

[I₂] =   (2.5-x)/1.5 = (2.5-1.37)/1.5 = 0.753 M