## Chemistry and Chemical Reactivity (9th Edition)

Any reaction involving the ions $Ba^{2+}$ and $PO_4^{3-}$ would be satisfactory, for example the following acid base reaction: $3\ Ba(OH)_2(aq)+2\ H_3PO_4(aq)\rightarrow Ba_3(PO_4)_2(s)+6\ H_2O(l)$ (Mixing barium hydroxide and phosphoric acid).