Ag(NH3)2+ is the chemical symbol for diamminesilver. It is the main chemical component in Tollens’ reagent and is used to determine if carbonyl compounds are an aldehyde or a ketone.
Tollens’ reagent is prepared with liquid silver nitrate (AgNO3) mixed with liquid sodium hydroxide (NaOH). The chemical reaction of these two aqueous compounds will instantly begin to change into brown precipitate or substance. Adding a few drops of liquid ammonia will dissolve the precipitate into a clear liquid. The chemical solution is now Ag(NH3)2+. The plus sign indicates the silver has a positively charged ion attached to it. This ion is complex, with the liquid silver ion bonding with liquid ammonia ion.
Once the solution is ready, the experiment is conducted by combining the diamminesilver in a test tube with a carbonyl compound. The test tube is then placed in a container of warm water. If the carbonyl is an aldehyde, it will be oxidized into a carboxylic acid, and a silver precipitate will form from the reduction of silver ions. The ions will stick to the inner surface of the test tube and have the appearance of shiny mirror. If the carbonyl is a ketone, the liquid will remain clear.
Tollens’ reagent should be used immediately. It has a short shelf life before silver nitrate is formed. This a highly explosive substance and must be handled with the utmost caution. Diamminesilver is safely disposed by diluting it with acid.