24.12 Silver Mirror

Chemical Concept Demonstrated: The reduction of silver ions to silver metal

Demonstration:

A silver solution (made up of 0.1M AgNO3 and 0.3M aqueous ammonia) and activator are poured into the flask and swirled to coat the inside. A reducer and activator are added, the flask is stoppered, and the solution is allowed to come into contact with the entire inside surface of the flask.

Observations:

    The entire inside surface of the flask is coated in silver metal.

Explanation:

    The inside surface is coated with a silver amine [Ag(NH₃)₂⁺] in the first step.  This compound can be reduced to form silver.  Although the reducer (possibly dextrose, but almost certainly a similar hydrocarbon) wouldn't be able to do this normally, the activator (essentially a strong base) makes the environment suitable for such a reduction.  Because the ions of the silver solution and the reducer only touch each other on the inside surface of the flask, the inside surface is the only place where silver metal forms.