Question

A 10 ml of (NH₄)₂ SO₄ was treated with an excess of NaOH. The evolved NH₃ gas absorbed in 50 ml of 0.1 N HCl. 20 ml of 0.1 N NaOH was required to neutralise the remaining HCl. The strength of (NH₄)₂ SO₄ in the solution is ______ g/L.

Options

• 10.03

• 07.52

• 19.8

• 5.25

Answer 1

A 10 ml of (NH₄)₂ SO₄ was treated with an excess of NaOH. The evolved NH₃ gas absorbed in 50 ml of 0.1 N HCl. 20 ml of 0.1 N NaOH was required to neutralise the remaining HCl. The strength of (NH₄)₂ SO₄ in the solution is 19.8 g/L.

Explanation:

m. eq. of remaining HCl = m. eq. of used NaOH to neutralize the remaining HCl

= 20 × 0.1 = 2

m. eq. of HCl taken initially = 50 × 0.1 = 5

∴ m. eq. of HCl in the absorption of NH₃ = 5 – 2 = 3

∴ m. eq. of NH₃ Produced = 3

Now m. eq. of NH₃ = m. eq. of (NH₄)₂ SO₄]

∴ m. eq. of (NH₄)₂ SO₄ = 3

It N be the normality of the given (NH₄)₂ SO₄,

Then N × 10 = 3

⇒ N = 0.3

Now strength of (NH₄)₂ SO₄ = N × eq. wt

`= 0.3 xx 132/2`

= 19.8 g/L