Reverse the reactions. Label the acids and bases on the left-hand side of each of the reversed equations?

1. HCl + NH3 => NH4+ + Cl-
2.NH3 + H2O => NH4+ +OH-
3. HCl +H2O => H3O+ +Cl-
4. H3PO4 +H20 => HPO4^-2 +H3O+
5.H2PO4- +H2O => HPO4^-2 +H3O+

1 answer

NH4^+ + Cl^- ==> NH3 + HCl
The acid is the one with more H. The base is the one with fewer H.
NH4^+ is the acid on the left; NH3 is the conjugate base on the right.
Cl^- is the base on the left; HCl is the conjugate acid on the right.