Question

Tarnish from copper utensils can be removed by using

• A. Methylated spirit
• B. Vinegar and salt
• C. White powder
• D. Acetone

Hint:

Standard domestic cleaning combinations for tarnish are based on mild acids:
- Copper/Brass: Acid + Salt (e.g., Vinegar + Salt, or Tamarind/Lemon + Salt).
- Silver: Reducing agents or specialized polishing agents.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Metallic utensils oxidize over time due to exposure to atmospheric moisture, oxygen, and carbon dioxide, forming a dull surface layer known as tarnish.
Removing this tarnish requires a chemical reaction that can solubilize the metallic oxide or carbonate without damaging the underlying metal.

Step 2: Detailed Explanation:
Copper utensils react with moist air to form a basic green layer of copper carbonate (\(\text{CuCO}_3 \cdot \text{Cu(OH)}_2\)), which acts as tarnish.
To clean this effectively, a mild acid is required to dissolve the basic copper carbonate.
Vinegar contains acetic acid (\(\text{CH}_3\text{COOH}\)), which acts as a mild acid.
When vinegar is mixed with salt (sodium chloride, \(\text{NaCl}\)), it forms a cleaning solution that releases hydrogen and chloride ions.
This chemical mixture reacts with the copper carbonate tarnish, breaking it down into soluble copper salts that can be easily wiped or washed away.
This restores the bright, metallic copper shine.
In contrast:
- Methylated spirit and acetone are organic solvents used to remove grease, lacquers, or organic stains (like nail polish), but they do not dissolve copper tarnish.
- Generic white powder (such as chalk) lacks the necessary acidic properties to break down metallic tarnish chemically.

Step 3: Final Answer:
Tarnish from copper utensils can be removed using Vinegar and salt.