Question

What is the formula for the compound composed of calcium and phosphate?

Answer 1

`CaHPO_4` or `Ca_3(PO_4)_2`

Explanation:

Calcium phosphates are a very broad church. I just read that the mineral apatite, which is the phosphate we put on our gardens as fertilizer is `Ca_5(PO_4)_3X` `(X=X^(-), HO^-)`.

Of course the phosphate ion, `PO_4^(3-)` is quite a strong base, and in aqueous solution exists as `HPO_4^(2-)`.