In the following reaction, H3PO4 (aq) + H2O (l) ⇄ H2PO4 - (aq) + H3O + (aq) what happens when more H2PO4 - (aq) is added to the solution?

The concentration of H₃PO₄ will increase.

Explanation:

H₃PO₄ (aq) + H₂O (l) ⇄ H₂PO₄⁻ (aq) + H₃O⁺ (aq)

According to Le Châtelier's Principle, when we apply a stress to a system at equilibrium, the system will respond in a way that tends to relieve the stress.

If we add more H₂PO₄⁻, the position of equilibrium will move to the left to get rid of the added H₂PO₄⁻.

The concentration of H₃PO₄ will increase.