Question

Silver articles become black on prolonged exposure to air. This is due to the formation of

• A. silver sulphide
• B. carbon
• C. silver sulphite
• D. black silver

Answer 1

The correct option is A

silver sulphide

Silver tarnish is the discoloration that occurs on silver. Silver is not appreciably affected by dry or moist air that is free from ozone, halogens, ammonia, and sulphur compounds. The presence of hydrogen sulphide in any material that silver comes into contact with is one of the prime reasons for silver tarnish. The hydrogen sulphide reacts with the silver to form silver sulphide.

$2Ag+H_{2}S\to A{g}_{2}S+H_2$

Silver sulphide is black. When a thin coating of silver sulphide forms on the surface of silver, it darkens the silver.