Question

State the observations you would make on adding sodium hydroxide to an aqueous solution of:

1. ​ferrous sulphate
2. aluminium chloride

Answer 1

1. When Sodium hydroxide is added to light green solution of Ferrous Sulphate, the colour changes to dark green precipitates of Ferrous Hydroxide. The reaction is :

FeSO_​4 + 2 NaOH $\to$ Na₂SO₄ + Fe(OH)₂

2. When a colourless solution of Aluminium Sulphate is treated with Sodium Hydroxide, the white flaky precipitates of Aluminium Hydroxide are formed. The reaction is :

Al₂(SO₄)₃ + NaOH $\to$ Al(OH)₃ + Na₂SO₄