Question

The hydride of group 15 dissolves in water to form a basic solution.Adding this solution to AgCl precipitates dissolves the precipitates.Why does this precipitate dissolve? Write chemical equation.​

Answer 1

NH3 which when added to AgCl precipitates [Ag(NH3)2]Cl due to the formation of complex diammine silver chloride.

2NH3 + AgCl ⇄ [Ag(NH3)2]Cl

White ppt. of AgCl appears on adding aq. HNO3.

• When HNO3 is added, it combines with ammonia to form ammonium nitrate which decreases the concentration of ammonia.

• Therefore the concentration of ammonia decreases.

• The equilibrium for the formation of silver ammonia complex shifts to left which decreases the chloride ion concentration and the increase in the concentration of chloride ions becomes 0.

• This causes the precipitate of silver chloride.