Question

Complete the following chemical reaction equation:
\[P{{H}_{3}}+HgC{{l}_{2}}\to \]

Answer 1

Hint: The given reactants are Phosphine ( $P{{H}_{3}}$) and mercuric chloride ( $HgC{{l}_{2}}$). When the Phosphine gas is absorbed in the mercuric chloride solution, corresponding phosphide along with an acid will be obtained.

Complete answer:
- Let’s start with the compound Phosphine. It’s a chemical compound with the chemical formula $P{{H}_{3}}$ and is a toxic, colourless, flammable gas. It’s classified as a pnictogen hydride. The pure phosphine is odourless whereas the technical grade samples has a high unpleasant odour due to the presence of di-phosphane (${{P}_{2}}{{H}_{4}}$) and substituted phosphine.
- The Mercury dichloride or mercuric chloride ($HgC{{l}_{2}}$) is an odourless crystalline solid which is white in colour and is a triatomic molecule where a mercury atom is bonded with two chlorines.
- $HgC{{l}_{2}}$ is corrosive to mucous membranes and is highly a toxic compound. $HgC{{l}_{2}}$ is widely used as an antiseptic, disinfectant, wood preservative, fungicide Etc.
- When phosphine is treated with mercuric chloride, the product formed will be mercuric phosphide ($H{{g}_{3}}{{P}_{2}}$ ) along with the formation of hydrochloric acid and the corresponding reaction can be written as follows
\[2P{{H}_{3}}+3HgC{{l}_{2}}\to \underset{{}}{\mathop{H{{g}_{3}}{{P}_{2}}}}\,+6HCl\]

Therefore when the Phosphine gas is absorbed in the mercuric chloride solution, mercuric phosphide along with hydrochloric acid will be obtained.

Note: There is a possibility of confusion between the compounds phosphine and phosgene. The major difference between phosphine and phosgene is that phosgene ($COC{{l}_{2}}$) is an organic compound whereas phosphine ($P{{H}_{3}}$) is an inorganic compound. Additionally, phosgene occurs as a colorless gas with the odor of freshly cut grass while phosphine occurs as a colorless, flammable and toxic gas with a slightly unpleasant odor.