04. A Giant Silver Mirror   Previous PageNext Page
       Method - The Demonstration

The demonstration

Place 150 cm of the silver nitrate solution in a 250 cm beaker and, working in a fume cupboard if possible, ass 880 ammonia using a dropping pipette. A brown precipitate will form. Continue to add the ammonia until the precipitate re-dissolves to give a clear, colourless solution. Less than 5 cm of ammonia will be needed. The solution then contains Ag() (aq).

Add 75 cm of the potassium hydroxide solution. A dark brown precipitate will form. Add more ammonia dropwise until this precipitate redissolves to give a clear, colourless solution. About 5 cm of ammonia will be needed.

Pour this solution into the 1 dm flask and add 12 cm of the glucose solution. Stopper the flask and swirl the solution so that the whole of the inner surface of the flask is wetted. The solution will turn brown. Continue swirling until a mirror forms. This will take about 2 minutes.


When a satisfactory mirror has formed, pour the solution down the sink with plenty of water. Rinse out the flask well with water and discard the washings down the sink. The flask can now be passed around the class.


An alternative to plating the inside of the flask is to silver plate the outside of a small glass objects which can be suspended in teh plating solution by hanging them on threads. These objects must be cleaned beforehand.

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