Potassium iodide forms a scarlet precipitate of mercuric iodide when added to mercuric chloride solution. The precipitate of mercuric iodide dissolves in excess of potassium iodide forming a complex

Options

A. `K_(2)HgI_(4)`
B. `K_(4)HgI_(6)`
C. `K_(3)HgI_(3)`
D. `KHgI_(2)`

Answer

A

Explanation

Mercuric iodide is obtained as a scarlet prcipitate on addition of postassium iodide to a solution of mercuric chloride. It can also be obtaned by grinding mercury with appropriate amount of iodine. Mercuric iodide, although sparingly soluble in water, dissolves readily in a solution of potassium iodide due to th eformation of iodo complex:
`HgCI_(2) + 2KI rarr 2KCI + Hf I_(2)`
`HgI_(2) + 2KI rarr K_(2)[Hg I_(4)]`
potassium tetraiodo-mercurate (II)
The teraiodo complex forms light yellow crystals, `K_(2)[Hg I_(4)]`. `2H_(2)O`, freely soluble in water and alcohol.