Formation of a Mirror

1. Formation of a Mirror A solution is added to a flask. Within seconds a brilliant mirrored surface forms on the inner wall of the flask

2. Purpose • To observe a silver plating reaction

3. Demonstration • Sugar was one of the solutions in the flask • A silver ion solution was the other solution • Oxidation of the carbon occurred when silver ion was reduced • The silver metal reduction product adhered to the glass reduction Ag Ag+

4. Concepts 1. Redox Reactions 2. Selective Organic Reactions

5. 1. Redox Reactions • In a redox reaction, one substance loses electrons while another substance gains electrons • “Redox” is a conventional term which is a combination of the words “reduction” AND “oxidation” • The substance that loses electrons is said to be oxidized and/or the reducing agent • The substance that gains electrons is said to be reduced and/or the oxidizing agent

6. 2. Selective Organic Reactions • Organic compounds may be totally oxidized to carbon dioxide and water • gasoline oxidation (combustion) • Organic compounds may be selectively oxidized by adding an oxygen atom to just one carbon • C O C O H O H oxidation

7. Conclusions • The formation of silver metal was due to the reduction of silver ion • The reducing agent for silver ion was the sugar • The sugar was simultaneously oxidized as the silver ion was reduced

8. Comments • Oxidation (the loss of electrons) of one specie is always accompanied by the reduction (the gain of electrons) of another specie • The reaction in this demonstration is the “Tollen’s Reaction” and is a test for the presence of oxidizable sugars