Hi, can you please help me with these questions.
Methane and chlorine react when irradiated with UV light. Explain why the reaction requires only a little flash of UV light rather than prolonged radiation.
Explain each of these observations as fully as you can.
1.
Sure, I can help you with that!
1. The reaction between methane and chlorine requires only a little flash of UV light rather than prolonged radiation because it is a photochemical reaction. In a photochemical reaction, the activation energy required for the reaction to occur is provided by the absorption of light energy. The light energy is absorbed by the reactant molecules, exciting them to a higher energy state. This higher energy state makes the reactant molecules more reactive and allows them to overcome the energy barrier required for the reaction to take place.
In the case of methane and chlorine, the UV light is absorbed by chlorine, causing it to undergo homolytic cleavage, which means that the chlorine molecule splits into two highly reactive chlorine atoms. These chlorine atoms can then react with methane molecules, resulting in the formation of chloromethane and hydrochloric acid.
The reason why only a little flash of UV light is required is that the absorption of light energy occurs very quickly, and the excited chlorine atoms react rapidly with the methane molecules. Therefore, prolonged exposure to UV light is not necessary as the reaction happens very quickly once the reactant molecules are excited.