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 Ag + Ag reduction

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 HHO 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