Question

0,5 mol of CO2 and 0,2 mol of H2 are put into a 5L vessel at a certain temperature. When the reaction CO2 (g) + H2 <-----> CO(g) + H2O(g), is reached equilibrium, the vessels contains 0,1 mol of CO. Calculate the equilibrium constant, Kc, for the reaction at given temperature.

Answer 1

..........................................CO2 (g).........H2.........CO.............H2O

The starting amounts..........0.5mol..........0.2mol....0................0

As you can see from equation CO2 (g) + H2 ---&gt; CO(g) + H2O(g), one mol of CO could be formed from one mol of CO2 and one mol of H2,also one mol of H2O is formed in this reaction,so using this:

The equilibrium amounts.....0.5-0.1........0.2-0.1......0.1............0.1

But it is in 5 L,and we need concentration:

The equilibrium conc...........(0.5-0.1)/5...(0.2-0.1)/5...0.1/5......0.1/5


Kc=[H2O][CO]/[CO2][H2]

Kc=(0.1/5)*(0.1/5) / (((0.5-0.1)/5)*((0.2-0.1)/5))=0.25