Writing a balanced net ionic equation 2

Question

• Write a balanced net ionic equation (no spectator ions) for the reaction that occurs when NaH₂PO₄ reacts with :
• a strong base =
• a strong acid =

Answer 1

First notice that H2PO4- is the conjugate base of phosphoric acid but that H2PO4- can also function as a weak acid undergoing another dissociation reaction. 

 

reaction with a strong base => use OH-

 

H2PO4- (aq) + OH- (aq) => HPO42- (aq)  + H2O (l)

 

reaction with a strong acid => use HCl

 

H2PO4- (aq)  + H+ (aq) => H3PO4 (aq)