Question

why is chloroform stored in dark coloured bottle containing ethanol?

Answer 1

Chloroform undergoes oxidation in presence of light and air.

Therefore, it is stored in dark coloured bottles, which are filled upto the brim.1% ethanol retards the oxidation and converts the phosgene formed into harmless ethyl carbonate.

COCI2 + 2C2H5 OH ——→ ( C2H5O)2 CO + 2HCI

 Ethylcarbonate 

Answer 2

Chloroform is stored in a dark-coloured bottle containing ethanol to prevent the formation of Phosgene.

Explanation:

• Chloroform undergoes oxidation in the presence of sunlight and air.
• The air contains oxygen that oxidises chloroform to Phosgene ($\[COC{l_2}\]$)  or Carbonyl chloride.

        $\[2CHC{l_3} + {O_2}\xrightarrow{{Sunlight}}2COC{l_2} + 2HCl\]$

• This gas is poisonous so its formation should be avoided.
• If oxidation of chloroform does not occur, phosgene will not be formed.
• Therefore, Chloroform is kept in dark bottles so that sunlight and air cannot enter and oxidation of chloroform cannot take place.

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