Question

Write a net ionic equation for the overall reaction that occurs when aqueous solutions of potassium hydroxide and phosphoric acid are combined. assume excess base.

Answer 1

The complete reaction for potassium hydroxide (KOH) and phosphoric acid (H3PO4) would yield products of water (H2O) and potassium phosphate (K3PO4).

3 KOH + H3PO4 ---> K3PO4 + 3 H2O

The net ionic equation would be obtained when you express the compounds in their ionic forms and eliminating the spectator ions. Spectator ions are the ions that appear in the reactant and product side. They do not actively participate the in the reaction.

3 K+ + 3 OH- + H3PO4  --->  3K+ + PO4^3- + 3 H2O

H3PO4 is a weak acid so it does not dissociate. H2O is not an ionic compound so it also does not dissociate. Therefore, the spectator ion is the potassium ion K+. The net ionic reaction is

3 OH- + 3 H3PO4  ---> PO4^3- + 3 H2O