Final answer:
The Tollens' test is used to distinguish aldehydes from ketones, where Ag2O in the form of the Tollens' reagent oxidizes aldehydes into carboxylic acids while reducing silver ions to metallic silver.
Step-by-step explanation:
The Tollens' test is a classical chemical test used to differentiate aldehydes from ketones based on the easy oxidation of aldehydes. Ag2O, or silver oxide, is used to prepare Tollens' reagent, which has the silver ion complex Ag(NH3)2+ in aqueous solution. When Tollens' reagent is added to an aldehyde, it gets oxidized and the silver ion is reduced, forming a metallic silver mirror on the walls of the test container.
During the reaction, the aldehyde is oxidized to a carboxylic acid. The overall chemical reaction can be represented as:
RCHO(aq) + 2Ag(NH3)2+(aq) + 3OH-(aq) → RCOO-(aq) + 4NH3(aq) + 2Ag(s) + H2O(l)
Here, RCHO represents the aldehyde group. This reaction is commonly used to deposit a thin layer of silver in processes like silvering of mirrors, where glucose or another reducing sugar with an aldehyde group is used as the reducing agent.