7.12 A mixture of 1.57 mol of N2, 1.92 mol of H2 and 8.13 mol of NH3 is introduced into a 20 L reaction vessel at 500 K. At this temperature, the equilibrium constant, Kc for the reaction N2 (g) + 3H2 (g) 2NH3 (g) is 1.7 × 102. Is the reaction mixture at equilibrium? If not, what is the direction of the net reaction?

 The given reaction is: 

N2g+3H2g2NH3g

The given concentration of various species is

 

N2=1.5720mol L-1 H2=1.9220mol L-1NH3=8.1320mol L-1

Now, the reaction quotient Qc is:

                 Qc=NH32N2H23                      =8.132021.57201.92203                  =2.4×103

Since, QcKc, the reaction mixture is not at equilibrium.

Again, Qc>Kc, Hence, the reaction will proceed in the reverse direction.