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?

Concentration of substance,

[substance] =


Thus, concentrations of given substances are,


[N2] = 1.57/20 mol L-1


[H2] = 1.92/20 mol L-1


[NH3] = 8.13/20 mol L-1


For a chemical change,


aA + bB ⇌ cC + dD


Reaction quotient Qc for the reaction is,


Qc =


Where [substance] is concentration of substance at a particular time.


For given reaction


N2 (g) + 3H2 (g)⇌2NH3 (g)


Reaction quotient is,


Qc = =


Qc >Kc . Therefore, the reaction proceeds in reverse direction in order to attain equilibrium. (Equilibrium constant is reaction coefficient at equilibrium state)


13