Question
What are Photo-chemical reactions? Describe the mechanism of reaction between hydrogen gas and chlorine gas when exposed to sunlight?
Solution
A photo-chemical rection may be defined as a process or reaction which is initiated by light absorption.
A reaction between H2 gas and chlorine gas is a photo-chemical reaction. The proposed mechanism for this reaction is given as follows:
Primary Process:
Secondary Process:
(step II)
(step III)
Step II and III are called chain propagation steps. The chain termination takes place on the walls of the reaction vessel by the reaction.
