Describe the observations when aqueous ammonia is added first a few drops and then in excess to copper(II) sulphate solution. (b) State the formula of the precipitate formed. 13. (a) State why glass i

When a few drops of aqueous ammonia are added to copper (II) sulphate solution, a pale blue precipitate of copper (II) hydroxide is formed.
When excess aqueous ammonia is added, the pale blue precipitate dissolves to form a deep blue solution of tetraamminecopper(II) complex.

The substance formed when a few drops of aqueous ammonia are added is copper (II) hydroxide.
Its formula is $\text{Cu}(\text{OH})_2$.

Nitric (V) acid is a highly corrosive and reactive acid. Glass is used for the apparatus because it is unreactive to most chemicals, including strong acids like nitric acid, preventing corrosion and contamination.

a) When a few drops of aqueous ammonia are added, a pale blue precipitate forms. When excess aqueous ammonia is added, the pale blue precipitate dissolves to form a deep blue solution.

b) The formula of the substance formed when few drops are added is $\boxed{\text{Cu}(\text{OH})_2}$.

a) All apparatus used during the preparation of nitric(V) acid are made of glass because glass is unreactive to most chemicals, including concentrated nitric acid, preventing corrosion.