Answer :

Cleaning silver ornament:
- Over the years silver ornaments gets tarnished to dull gray color.
- This is due to formation of silver sulphide coat on the ornament.
- The silver sulphide is converted back into silver by addition of more addition of more reactive metal like aluminium.

Chemical reaction :

Silver sulphide + aluminium gives rise to silver + aluminium sulphide
3ag2s 2al gives rise to 6ag al2s3

Hope its help you

**Cleaning Silver Ornaments by Goldsmiths**

**Introduction:**
Goldsmiths often deal with precious metals like gold and silver. Over time, silver ornaments tend to lose their shine and develop tarnish due to exposure to air and other environmental factors. To restore the luster and beauty of silver ornaments, goldsmiths employ various cleaning techniques. One common method is using chemical reactions to remove tarnish and restore the shine of silver ornaments.

**Chemical Reaction Involved:**
The chemical reaction used by goldsmiths to clean silver ornaments involves a process called oxidation-reduction, commonly known as redox reaction. The reaction can be represented as follows:

2Ag(s) + H2S(g) + 2H2O(l) → Ag2S(s) + 4H+(aq)

In this reaction, silver (Ag) reacts with hydrogen sulfide gas (H2S) and water (H2O) to form silver sulfide (Ag2S) and hydrogen ions (H+).

**Explanation:**
1. **Tarnish on Silver Ornaments:** Tarnish on silver ornaments is primarily caused by the reaction of sulfur-containing compounds in the air, such as hydrogen sulfide (H2S), with the silver surface. This reaction leads to the formation of a thin layer of silver sulfide (Ag2S) on the ornament, giving it a dull appearance.

2. **Redox Reaction:** To remove the tarnish and restore the shine, goldsmiths utilize a redox reaction. In this reaction, the silver sulfide (Ag2S) is converted back into silver (Ag) by displacing the sulfur atoms with hydrogen ions (H+). Hydrogen sulfide gas (H2S) is used as a source of sulfur.

3. **Reaction Process:** The silver ornament is immersed in a solution containing hydrogen sulfide gas (H2S) and water (H2O). The hydrogen sulfide reacts with the silver sulfide layer on the ornament, converting it into silver sulfide (Ag2S). Simultaneously, water provides the necessary medium for the reaction to occur.

4. **Formation of Silver Sulfide:** The silver sulfide (Ag2S) formed during the reaction is a black compound. As the reaction progresses, the silver sulfide layer gradually gets removed from the surface of the ornament, exposing the underlying silver.

5. **Restoring the Shine:** As the silver sulfide is removed, the silver surface of the ornament is revealed, restoring its original shine and luster. The time required for the reaction depends on the extent of tarnish on the ornament.

**Conclusion:**
Goldsmiths employ a redox reaction to clean silver ornaments by removing the tarnish caused by the reaction of silver with sulfur-containing compounds. The reaction involves the use of hydrogen sulfide gas and water, which convert the silver sulfide into silver and restore the shine of the ornament. By following this chemical process, goldsmiths can effectively clean and restore the beauty of silver ornaments.