Question

How do calcium ion and phosphate ion react in water?

Answer 1

`3Ca^(2+) + 2PO_4^(3-) rarr Ca_3(PO_4)_2(s)darr`

Explanation:

Phosphates are usually as soluble as a brick, and all except the alkali metal salts come a crashing out of solution. In fact, the phosphate species in aqueous solution is probably, `HPO_4^(2-)`, `"biphosphate"`, and the precipitate is thus possibly `CaHPO_4(s)`.