Question

A fuel cell differs from a battery because the current is being generated from a reduction-oxidation (redox) reaction in which the reactant is consumed. A classic example of a fuel cell is the phosphoric acid fuel cell (PAFC), which have been used in stationary power generators, buses, and even submarines. Fuel cells require an electrolyte (similar to batteries) to carry electrically charged species between the electrodes, and a PAFC utilizes phosphoric acid (H3PO4) as its electrolyte. The weak acid phosphoric acid has three acidic protons, highlighted in red here: H3PO4.

As a weak acid, some of the acid will remain in molecular form when dissolved in water.

Write the net ionic equation that depicts the dissociation of the first proton including charges for any ions produced.

Answer 1

H₃PO₄(aq) ⇄ H₂PO₄⁻(aq) + H⁺(aq)

Step-by-step explanation:

The phosphoric acid fuel cell (PAFC) employs phosphoric acid (H₃PO₄), a weak acid that dissociates in 3 steps, each with its acid dissociation constant.

H₃PO₄(aq) ⇄ H₂PO₄⁻(aq) + H⁺(aq) Ka1

H₂PO₄⁻(aq) ⇄ HPO₄²⁻(aq) + H⁺(aq) Ka2

HPO₄²⁻(aq) ⇄ PO₄³⁻(aq) + H⁺(aq) Ka3