$$Na_3AsO_4(aq) + BaCl_2(aq) \rightarrow Ba_3(AsO_4)_2(s) + 3NaCl(aq)$$

Equazione ionica netta:

$$3Ba^{2+}(aq) + 2AsO_4^{3-}(aq) \rightarrow Ba_3(AsO_4)_2(s)$$