a)  $H_{3}P{O}_4$  

równanie z jonem OH^-:   $\underset{\text{kwas 1}}{H_{3}P{O}_4}+\underset{\text{zasada 2}}{O{H}^{-}}\rightleftarrows \underset{\text{zasada 1}}{H_{2}P{O}_4^{-}}+\underset{\text{kwas 2}}{H_{2}O}$  

b)   $P{O}_4^{3-}$  

równanie z jonem H₃O⁺:  $\underset{\text{zasada 1}}{P{O}_4^{3-}}+\underset{\text{kwas 2}}{H_3{O}^{+}}\rightleftarrows \underset{\text{kwas 1}}{HP{O}_4^{2-}}+\underset{\text{zasada 2}}{H_{2}O}$