Question

The value of K_c for the reaction of dinitrogen tetroxide to make nitrogen dioxide is 2.3776. The concentration of nitrogen dioxide 1.4331 M with no dinitrogen tetroxide. What is the equilibrium concentration (in M) of nitrogen dioxide?

Answer 1

The equilibrium constant for the formation of nitrogen dioxide from dinitrogen tetraoxide is 2.3776.

i.e N₂O₄   <----------> 2NO₂   Kc = 2.3776

For the backward reaction, we have ,

2NO₂ <----------> N₂O₄   Kc = 0.4206

1 0

1.4331(1 - 2a) 1.4331a

0.4206 = (1.4331a) /[1.4331(1-2a)]²

1 + 4a² - 4a = 1.659a

1+ 4a² - 5.659a = 0

by solving we get :-

a = 0.2069 and a= 1.2077

by neglecting a = 1.2077 we get

a = 0.2069

equilibrium concentration of nitrogendioxide = 1.4331( 1- 0.4138) = 0.8400 M

equilibrium concentration of dinitrogen tetraoxide = 0.2965