Question

Sodium thiosulphate solution turn cloudy when it reacts with nitric acid:

a. Due to the formation NaNO3

b. Due to the evolution of SO2 gas

c. Due to the formation of S.

d. None of the above.

Answer 1

Answer:The solution turn cloudy due to the formation of elemental sulphur as precipitate.

Explanation:

Nitric acid is a very good oxidizing agent and it oxidizes sodium thiosulphate

into sodium sulphate.

The following reaction takes place when nitric acid reacts with sodium thiosulphate.

Na₂S₂O₃+2HNO₃→Na₂SO₄+S+2NO₂+H₂O

On reaction of sodium thiosulphate  with nitric acid the following products are obtained:

1.Sodium sulphate(Na₂SO₄)

2.Precipitate of elemental sulphur(S)

3. Nitrogen dioxide (NO₂)

4.water molecule(H₂O)

The overall solution turns cloudy because of the formation of elemental sulphur as precipitate.