Question

A sample of gas in which [h2s] = 5.25 m is heated to 1400 k in a sealed vessel. after chemical equilibrium has been achieved, what is the value of [h2s]? assume no h2 or s2 was present in the original sample.

Answer 1

When the reaction equation is:

by using the ICE equation:

                   2H2S(g)  ↔ 2 H2(g) +  S2(s)

initial            5.25                 0            0

change         -2X                 +2X         +X

Equ           (5.25-2X)              2X           X

and when Kc = 2.2 x 10^-4 

Kc = [H2]^2/ [H2S]^2

    = (2x)^2 / (5.25-2X)^2 by solving for X 

∴X = 0.038 M

∴[H2S] = 5.25 - 2X 

             = 5.25 - (2*0.038)

            = 5.174 M