$$2AgCl \xrightarrow{hv} 2Ag + Cl_2$$

The reaction is an example of a photochemical reaction, where light energy is absorbed by the reactant to initiate the reaction. In the case of silver chloride, the light energy is absorbed by the chloride ions, which causes them to become excited and eject electrons. The electrons are then transferred to the silver ions, which are reduced to silver atoms. This process continues until all of the silver chloride is decomposed into silver and chlorine gas.