Chapter 19, Problem 93A

Interpretation Introduction

Interpretation:

The process of cleaning tarnished silverware by a redox chemical process needs to be explained.

Concept introduction:

Silver gets black in air due to tarnishing. It reacts with hydrogen sulphide gas forming silver sulphide which is black in color. That’s why silver become black due to coating of silver sulphide on it.

Answer to Problem 93A

The redox reaction to clean tarnishing is:

$3A{g}_{2}S+2Al\to A{l}_2{S}_3+6Ag$

Explanation of Solution

In the given reaction, aluminium metal reacts with silver sulphide and replaces silver from its salt. This reaction is a redox reaction.

$2Al+6A{g}^{+}\to 2A{l}^{3+}+6Ag$

Aluminium metal acts as reducing agent and reduces silver ions to silver thereby removing the black coating on silverware.

Conclusion

Aluminium metal helps to remove tarnishing on silver metal.