Question

\[MgS{O_4}\] on reaction with \[N{H_4}OH\] and \[N{a_2}HP{O_4}\] forms a white crystalline precipitate. What is its formula?
(A) \[Mg(N{H_4})P{O_4}\]
(B) \[M{g_3}{(P{O_4})_2}\]
(C) \[Mg{(OH)_2}\]
(D) \[MgS{O_4}\]

Answer 1

Hint: To answer this question we should think in terms of precipitation reaction. Usually an insoluble salt forms in aqueous medium.

Complete step by step answer:
A precipitation reaction usually involves the formation of an insoluble salt when two solutions containing soluble salts are combined. The insoluble salt that accumulates at the bottom of solution is known as the precipitate; hence the reaction is named so.
A precipitation reaction helps to determine the presence of various ions in solution. A solubility table is used to predict precipitation reactions. A precipitation reaction can occur when two solutions containing different salts are mixed, and a cation/anion pair in the resulting combined solution forms an insoluble salt; this salt then precipitates out of solution. In the question given here, a white precipitate of Magnesium ammonium phosphate is formed when Magnesium sulphate reacts with Ammonium hydroxide and Sodium hydrogen phosphate. The reaction proceeds as it is shown here:
\[MgS{O_4} + N{a_2}HP{O_4} + N{H_4}OH \to Mg(N{H_4})P{O_4} \downarrow + N{a_2}S{O_4} + {H_2}O\]
Hence, the correct answer is Option (A) \[Mg(N{H_4})P{O_4}\]

Additional information:
Solubility is the ability of a solid, liquid, or gaseous chemical substance to form a solution. The solubility of a substance generally depends on the type of solvent used, along with the temperature and pressure. The solubility of a substance in a particular solvent is measured by the concentration of the saturated solution.

Note: To predict whether a compound will be soluble in a given solvent, we should remember the saying, “Like dissolves like.” For example highly polar ionic compounds such as salt readily dissolve in polar solvents like water, but do not readily dissolve in nonpolar solutions like benzene or chloroform.