Question

Name the chloride of a metal which is soluble in excess of a ammonium hydroxide. Write the equation.

Answer 1

Zinc chloride is soluble in excess of ammonium hydroxide.

This reaction takes place in two stages.

1. If a little aqueous ammonia solution is added to zinc chloride a white precipitate of zinc hydroxide forms.

ZnCl2 + 2NH4OH -----> Zn(OH)2(s) + 2NH4Cl

Zinc hydroxide(White ppt.)

2. If more ammonia is added, then the precipitated zinc hydroxide redissolves to a colourless solution of a soluble zinc ammine, a complex ion.

Zn(OH)2(s) + 2NH4OH + 2NH4Cl --------> [Zn(NH3)4] Cl2 + 4H2O

Tetrammine Zinc chloride