Question

phosphoric acid $(h_{3}po_{4})$ is a polyprotic acid. write balanced chemical equations for the sequence of reactions that phosphoric acid can undergo when its dissolved in water.

Explanation:

Step1: First ionization

Phosphoric acid (\(H_3PO_4\)) donates one \(H^+\) ion.

$$H_3PO_4(aq)+H_2O(l) ightleftharpoons H_3O^+(aq)+H_2PO_4^-(aq)$$

Step2: Second ionization

\(H_2PO_4^-\) donates one \(H^+\) ion.

$$H_2PO_4^-(aq)+H_2O(l) ightleftharpoons H_3O^+(aq)+HPO_4^{2 - }(aq)$$

Step3: Third ionization

\(HPO_4^{2 - }\) donates one \(H^+\) ion.

$$HPO_4^{2 - }(aq)+H_2O(l) ightleftharpoons H_3O^+(aq)+PO_4^{3 - }(aq)$$

Answer:

$$H_3PO_4(aq)+H_2O(l) ightleftharpoons H_3O^+(aq)+H_2PO_4^-(aq)$$

$$H_2PO_4^-(aq)+H_2O(l) ightleftharpoons H_3O^+(aq)+HPO_4^{2 - }(aq)$$

$$HPO_4^{2 - }(aq)+H_2O(l) ightleftharpoons H_3O^+(aq)+PO_4^{3 - }(aq)$$