One mole of H2O and one mole of CO are taken in 10 L vessel and heated to 725 K. At equilibrium 40% of water (by mass) reacts with CO according to the equation,
H2O (g) + CO (g) ⇌H2 (g) + CO2 (g)
Calculate the equilibrium constant for the reaction.
Initially there was 1 mole of H2O and CO in a 10 L flask.
At equilibrium, 40% of H2O has reacted thus amount of H2O remaining is 0.6 mole.
The amount of CO reacted is also 0.4 mole.
Amount of H2 and CO2 formed is also 0.4 mole
H2O (g)+ CO (g)⇌H2 (g) + CO2 (g)
H2O (g) + CO (g) ⇌H2 (g) + CO2 (g)
Equilibrium constant for the reaction is,
Kc = 
= 
= 4/9
14