Chemical Equilibrium

2H2O(aq) ⇌ 2H2O(l)+ O2(g)

When volume is increased, the equilibrium position will shift to the right.

Explanation 1:
In the equation, there is no gaseous compound on the left hand side, but 1 moleof oxygen gas on the right hand side. Whenthe volume is increased, the total pressure of the system is consequentlydecreased. According to Le Chatelier'sprinciple, the equilibrium position will shift to the right to increase thenumber of gaseous molecules.

Explanation 2:
This is a heterogeneous equilibrium system. The equilibrium law is:
KP = PO2
When the volume is increased, PO2 is decreased and it is not equalto KP any longer. Toestablish a new equilibrium state, the equilibrium position will shift to theleft to increase PO2 until it is equal to KP.