7.16 What is the equilibrium concentration of each of the substances in the equilibrium when the initial concentration of ICl was 0.78 M ?

2ICl (g) I2 (g) + Cl2 (g); Kc = 0.14

The given reaction is:
                              2ICIg          I2g          Cl2gInitial conc.          0.78 M                0                0At equilibrium       0.78-2xM     xM           xM
Now, we can write,
 I2Cl2ICl2=Kcx×x(0.782x)2=0.14x2(0.782x)2=0.14x0.782x=0.374x=0.2920.748x1.748x=0.292x=0.167
Hence, at equilibrium,
 H2=I2=0.167 MHI=0.78-2×0.167 M       =0.446 M