Aldehydes reduce silver ions in Tollen’s reagent to metallic silver, forming a reflective silver mirror on the inside of a glass container. This classic test is used to identify aldehydes and reducing sugars.

1. Add 5 mL of 10% silver nitrate solution to a clean flask.
2. Add 1 mL of 10% sodium hydroxide solution.
3. Add concentrated ammonia drop by drop until the brown silver oxide just dissolves, leaving a clear or slightly dark solution.
4. Introduce 7 mL of 1% glucose solution and swirl gently.
5. Within minutes, a silver mirror will form on the inner walls of the flask.

Demonstration of Tollens' Reagent - Rugby School Chemistry:

Tollens Test - Silver mirror Reaction - MrGrodskiChemistry:

📄 Identification of Aldehydes – Tollen's Test - University of Colorado Boulder: https://www.colorado.edu/lab/lecture-demo-manual/o630-identification-aldehydes-tollens-test

📄 Tollens' Test for Aldehydes - University of Washington: https://chem.washington.edu/lecture-demos/tollens-test-aldehydes

• Use different aldehydes instead of glucose to compare reactivity.
• Perform the test in a test tube instead of a flask for quicker observation.
• Demonstrate with reducing sugars (such as fructose or lactose) to show biological relevance.

• Wear gloves to prevent skin staining from silver nitrate.
• Avoid contact of silver nitrate with skin or clothing, as it leaves permanent stains.
• Work in a well-ventilated area to minimize inhalation of ammonia vapors.
• Use concentrated nitric acid carefully to remove the silver mirror after the experiment.
• Dispose of silver waste according to local hazardous waste protocols.

• Why does Tollen’s reagent react with aldehydes but not most ketones? (Aldehydes are more easily oxidized than ketones.)
• What role does ammonia play in preparing Tollen’s reagent? (It dissolves the silver oxide, forming the reactive diamminesilver(I) complex.)
• Could this test distinguish between glucose and sucrose? (Yes, glucose is a reducing sugar and gives a positive test, while sucrose does not.)