Final answer:
To find the concentration of H3O+ for a triprotic acid at each equilibrium stage, conduct stoichiometric calculations followed by calculations using the dissociation constants step by step, treating each ionization separately.
Step-by-step explanation:
For a triprotic acid (H3A), the calculation of the concentration of H3O+ after each equilibrium stage involves stoichiometric and equilibrium calculations. Initially, you would calculate the changes in concentration after adding a base in a stoichiometric manner, then use the equilibrium constant to find the equilibrium concentrations of the acid, its conjugate base, and H3O+.
The first dissociation is H3A <=> H+ + H2A-. By setting up an ICE table (Initial, Change, Equilibrium), you can find the equilibrium concentrations. The first dissociation provides the initial concentration of H3O+. For the second dissociation, H2A- <=> H+ + HA2-, you use the first ionization's equilibrium concentration to calculate consequent dissociation. Each step should be treated separately. This process involves the use of the acid dissociation constants (Ka) and assumes the first ionization constant to be significantly larger than the second, simplifying calculations.