Answer :

In qualitative analysis, when H2S gas is passed through an aqueous solution of salt acidified with HCl, a black ppt of CuS is formed.

CuSO4 + H2S + dil HCl CuS + H2SO4

(Black ppt)

When ppt of CuS is boiled with dilute HNO3,it forms a blue coloured solution due to the following reactions given below:

3CuS + 8HNO3 3Cu(NO3)2 + 2NO + 3S + 4H2O

S + 2HNO3 H2SO4 + NO

2Cu2+ + SO42- + 2NH3 + 2H2O Cu(OH)2 + CuSO4 + 2NH4OH

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses

<span lang="EN-USChemistry - Board Papers

<span lang="EN-USChemistry - Board Papers

When an oxide of Chemistry - Exemplar

Identify compoundChemistry - Exemplar

A violet compoundChemistry - Exemplar