Question

When \(\mathrm{Na}_{3} \mathrm{PO}_{4}(a q)\) is added to a solution containing a metal ion and a precipitate forms, the precipitate generally could be one of two possibilities. What are the two possibilities?

Short answer

When \(\mathrm{Na}_3 \mathrm{PO}_4(aq)\) is added to a solution containing a metal ion, the two possible precipitates that can form are calcium phosphate \(\mathrm{Ca_3(PO_4)_2(s)}\) and aluminum phosphate \(\mathrm{AlPO_4(s)}\). This is because phosphate ions have low solubility with many metal ions, particularly calcium ions \(\mathrm{Ca}^{2+}\) and aluminum ions \(\mathrm{Al}^{3+}\).

Step-by-step solution

Identify the ions present in the sodium phosphate solution

In a sodium phosphate solution, we have sodium ions \(\mathrm{Na}^+\) and phosphate ions \(\mathrm{PO}_4^{3-}\). When the solution comes into contact with the solution containing the metal ions, the phosphate ions will most likely bond with the metal ions.

Understanding bonding with phosphate ions

Phosphate ions have a charge of -3, which means they can form ionic bonds with metal ions having positive charges. Metal ions usually have a charge of +1, +2, or +3.

Identifying common metal ions that form precipitates with phosphate ions

Based on solubility rules and common metal ions found in chemistry, the most common metal ions that form precipitates with phosphate ions are calcium ions \(\mathrm{Ca}^{2+}\) and aluminum ions \(\mathrm{Al}^{3+}\). These ions are known to form insoluble salts with phosphate ions.

Writing the chemical formulas for the precipitates

When the metal ions \(\mathrm{Ca}^{2+}\) and \(\mathrm{Al}^{3+}\) form precipitates with phosphate ions, the following precipitates are formed: 1. Calcium phosphate: \(\mathrm{Ca_3(PO_4)_2(s)}\) 2. Aluminum phosphate: \(\mathrm{AlPO_4(s)}\) In conclusion, the two possibilites for the precipitates when \(\mathrm{Na}_{3} \mathrm{PO}_{4}(aq)\) is added to a solution containing a metal ion are calcium phosphate \(\mathrm{Ca_3(PO_4)_2(s)}\) and aluminum phosphate \(\mathrm{AlPO_4(s)}\).