2h2s(g)⇌2h2(g)+s2(g),kc=1.67×10−7 at 800∘c is carried out at the same temperature with the following initial concentrations: [h2s]=0.100m, [h2]=0.100m, and [s2]=0.00 m. find the equilibrium concentration of s2. express the molarity to three significant figures.

Answer : The concentration of at equilibrium will be,

Explanation :  Given,

Equilibrium constant =

Initial concentration of = 0.100 M

Initial concentration of = 0.100 M

Initial concentration of = 0.00 M

The balanced equilibrium reaction is,

Initial conc.    0.1                0.1          0

At eqm.         (0.1-2x)       (0.1+2x)      x

The expression of equilibrium constant for the reaction will be:

Now put all the values in this expression, we get :

By solving the term 'x' by quadratic equation, we get two value of 'x'.

Concentration of at equilibrium =

Therefore, the concentration of at equilibrium will be,