Question

Why is chloroform stored in dark coloured bottles?

Hint:

Chloroform stored in dark bottles to prevent formation of toxic phosgene.

Answer 1

Why is chloroform stored in dark coloured bottles?

Solution:
Step 1: Understanding the nature of chloroform.
Chloroform (trichloromethane, \( CHCl_3 \)) is a volatile, colourless liquid that is sensitive to light. It can decompose when exposed to sunlight or prolonged exposure to artificial light. This decomposition leads to the formation of toxic by-products, including phosgene (a highly toxic and poisonous gas).

Step 2: The role of light exposure.
When chloroform is exposed to light, it undergoes a photochemical reaction that can produce harmful substances, such as phosgene, which is dangerous to human health. Therefore, to prevent this unwanted decomposition and the formation of these hazardous by-products, chloroform must be shielded from light.

Step 3: Why dark-coloured bottles?
Dark-coloured bottles, typically amber or brown, are designed to absorb and block the harmful light rays that can trigger the decomposition of chloroform. This ensures that the chloroform remains stable and free from degradation, making it safer for storage and use.

Final Answer: Chloroform is stored in dark coloured bottles to protect it from light, preventing its decomposition and the formation of harmful by-products like phosgene.