1. Silver nitrate (AgNO₃): This provides the silver ions (Ag⁺) necessary for the reaction.
2. Ammonia (NH₃): This reacts with the silver ions to form a complex ion, diamminesilver(I) ion ([Ag(NH₃)₂]⁺), which is the actual reactive species in the Tollens' test.
The reaction of silver nitrate with ammonia can be represented as:
AgNO₃(aq) + 2 NH₃(aq) → [Ag(NH₃)₂]⁺(aq) + NO₃⁻(aq)
However, the overall composition of Tollens' reagent is not fixed, as it's typically prepared fresh right before use. The exact proportions of silver nitrate and ammonia may vary, but a common approach is:
1. Dissolve silver nitrate in water.
2. Add a dilute ammonia solution dropwise until the initial white precipitate of silver oxide (Ag₂O) dissolves completely, forming a clear solution.
Therefore, there is no single molecular formula for Tollens' reagent. It's a solution containing a mixture of diamminesilver(I) ions ([Ag(NH₃)₂]⁺) and nitrate ions (NO₃⁻), along with excess ammonia.
