Question

Chloroform reacts with oxygen in the presence of light to give:
A ) Carbon tetrachloride
B ) Carbonyl chloride
C ) methyl chloride
D ) methylene dichloride
E ) acetaldehyde

Answer 1

Hint: The product will contain oxygen, chlorine and carbon. It is a highly toxic gas.

Complete step by step answer:
The chemical formulae of various compounds are as listed below:

Compound	Chloroform	Oxygen	Carbon tetrachloride	Carbonyl chloride	methyl chloride	methylene dichloride	Acetaldehyde
Chemical formula	$$\mathrm{C}\mathrm{H}\mathrm{C}{\mathrm{l}}_3$$	$${\mathrm{O}}_2$$	$$\mathrm{C}\mathrm{C}{\mathrm{l}}_4$$	$$\mathrm{C}\mathrm{O}\mathrm{C}{\mathrm{l}}_2$$	$$\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{l}$$	$$\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{l}}_2$$	$$\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{H}\mathrm{O}$$

In presence of light, chloroform reacts with oxygen to form carbonyl chloride. Carbonyl chloride is a poisonous (highly toxic) gas and is also known as phosgene. Carbonyl chloride has a smell which is similar to freshly-cut grass. In addition to carbonyl chloride, the other product obtained in this reaction is hydrogen chloride. Write the balanced chemical equation for the reaction.

$$\text{CHC}{\text{L}}_{\text{3}}\text{ + }{\displaystyle \frac{\text{1}}{\text{2}}}\text{O}\text{2}\stackrel{hv}{\to }\text{COC}{\text{L}}_{\text{2}}\text{ + HCL}$$

To prevent the formation of toxic phosgene gas, there are two approaches. First one is to avoid direct contact with light. Second one is to avoid direct contact with oxygen. The above reaction will not occur if either light or oxygen is absent.

To avoid formation of poisonous carbonyl chloride, chloroform is usually stored in dark coloured bottles. Dark (amber) coloured bottles prevent light from coming into contact with chloroform. To avoid contact of chloroform with atmospheric oxygen, chloroform is filled upto brim.

If the reaction of chloroform is carried out in absence of light and at high temperature, the products obtained are carbon monoxide and hydrogen chloride.

Hence, option (B) is the correct option:

Note:
The number of carbon atoms in the product should not be greater than the number of carbon atoms in chloroform.