Tollen's reagent is primarily used in organic chemistry to distinguish between aldehydes and ketones. When an aldehyde is present, it reacts with Tollen's reagent to produce a silver mirror coating on the inner surface of the reaction vessel, indicating a positive test. This reaction is a key method for identifying aldehydes in various compounds. Additionally, Tollen's reagent is employed in the synthesis of carboxylic acids from aldehydes, as the aldehyde group is oxidized to a carboxyl group. Its application is also found in the field of analytical chemistry for the detection of reducing sugars, which contain aldehyde groups that react similarly. Overall, Tollen's reagent serves as a valuable tool in both qualitative analysis and organic synthesis.