Question

How many milliliters of hydrogen sulphide are needed to precipitate cupric sulphide completely from a solution of 100ml?

Answer 1

The reaction of AgNO3 with H2S is:

2AgNO3 + H2S → Ag2S + 2HNO3

1 mole of H2S reacts with 2 moles of AgNO3

So, the ratio of amount of H2S required precipitating all the metal ions from 100 mL 1 M AgNO3 is,

1 H2S : 2AgNO3

The reaction of CuSO4  with H2S can be represented as follows:

CuSO4 + H2S → CuS + H2SO4

Here, 1 mole of H2S reacts with 1 mole of CuSO4

Hence,

The ratio of amount of H2S required precipitating all the metal ions from 100 mL 1 M CuSO4 is,

1H2S : 1CuSO4