Reduction of Tollen’s Reagent:
Tollen’s reagent is an ammoniacal solution of silver nitrate and is prepared by adding an aqueous solution of NH4OH to that of AgNO3 till the precipitate of AgOH initially formed just redissolves. Upon heating an aldehyde with Tollen’s reagent the latter is reduced to metallic silver which gets deposited on the inner walls of the test tube and shines like a mirror. This reaction is often called the silver mirror test.