Question

On exposure to air, silver articles turn blackish after some time.

Hint:

Silver tarnishing occurs due to the reaction with hydrogen sulfide in the air, forming silver sulfide (\(Ag_2S\)), which is black. To prevent tarnishing, store silver in airtight containers and clean it regularly.

Answer 1

Step 1: Understanding the blackening of silver
Silver (\(\text{Ag}\)) is a metal that reacts slowly with sulfur-containing compounds in the air. One such compound is hydrogen sulfide (\(\text{H}_2\text{S}\)), which is present in polluted air or released from decaying organic matter.
Step 2: The chemical reaction involved
When silver comes in contact with hydrogen sulfide, it reacts to form silver sulfide (\(\text{Ag}_2\text{S}\)), a black compound: \[ 2\text{Ag} + \text{H}_2\text{S} \rightarrow \text{Ag}_2\text{S} + \text{H}_2 \] This reaction causes the gradual blackening of silver articles.
Step 3: Preventive measures
- Storing silver articles in airtight containers or wrapping them in anti-tarnish cloths helps prevent tarnishing.
- Regular cleaning with mild acids like vinegar or lemon juice can help remove silver sulfide. Thus, silver articles turn black due to the formation of silver sulfide (\(\text{Ag}_2\text{S}\)) when exposed to air containing hydrogen sulfide (\(\text{H}_2\text{S}\)).