Question

When $CHC{l_3}$ is exposed to light and air. It gives:
(A) $C{l_2}$
(B) $C{H_3}Cl$
(C) Phosgene
(D) Phosphene

Answer 1

Hint: Chloroform is harmful to health and prevented from direct exposure to sunlight. Such types of chemicals on exposure to air under sunlight give free radical reactions and form harmful compounds.

Complete step by step answer:
In exposure to sunlight in the presence of oxygen and moisture chloroform gives highly toxic gas, phosgene ($COC{l_2}$ ) and hydrochloric acid ($HCl$ ).
The final answer is option ‘C’.
Additional information: Air and moisture in the presence of sunlight oxidize chloroform to phosgene. The reactions can be represented as:
$
  2CHC{l_3}(l) + {O_2}(g) \to 2COC{l_2}(g) + 2HCl(g) \\
  2CHC{l_3}(l) + 2{H_2}O(l) \to 2COC{l_2}(g) + 6HCl(g) \\
 $
Phosgene is a highly toxic gas which interacts with the proteins in the alveoli at the site of gas exchange and damages the blood-air barrier causing suffocation. In high doses it can kill a person by asphyxiation. It smells like moldy hay and causes irritation almost six times more dangerous than chlorine. Hence, chloroform is stored in dark bottles filled upto the brim and kept in dark to prevent any oxidation. Phosgene and hydrochloric acid are used in the manufacture of urethanes and polycarbonate plastics. Both phosgene and chlorine were used as chemical weapons during World War I. Chlorine can be identified by its green colour but phosgene is colorless thus soldiers did not at first know that they had received a fatal dose. One or two days after exposure the victim’s lungs would fill with fluid and they would slowly suffocate to death. Germans were the first to use it on the battle-field, it became the primary chemical weapon of the Allies. It alone was responsible for about 85% of chemical-weapons fatalities in World War I.
Note:
Phosgene is a compound of chlorine and oxygen so you should not be confused with phosphorus compounds. Phosgene is the common name of carbon oxychloride.It is also used to make plastics and pesticides.