Question

Write balanced equation for the following reactions : An aqueous solution of sodium hydroxide is added dropwise to a solution of gallium chloride in water. A precipitate is formed initially which dissolves on further addition of NaOH solution.

Answer 1

Sodium hydroxide is used to identify the basic cation.

Sodium hydroxide and gallium chloride are ionic compounds. When aqueous solutions of these two compounds are mixed and if a precipitate is formed it means mutual ion exchange has taken place.

If this insoluble substance dissolves on further addition of sodium hydroxide, it means a soluble complex is formed.

$3NaOH + GaCl_3\rightarrow Ga(OH)_3 + 3NaCl$  insoluble

$Ga(OH)_3 + NaOH \rightarrow Na[Ga(OH)_4]$ soluble

Answer 2

Sodium hydroxide and gallium chloride are ionic compounds. When aqueous solutions of these two compounds are mixed and if a precipitate is formed it means mutual ion exchange has taken place.

If this insoluble substance dissolves on further addition of sodium hydroxide, it means a soluble complex is formed.

3NaOH + GaCl_3\rightarrow Ga(OH)_3 + 3NaCl3NaOH+GaCl3​→Ga(OH)3​+3NaCl insoluble

Ga(OH)_3 + NaOH \rightarrow Na[Ga(OH)_4]Ga(OH)3​+NaOH→Na[Ga(