To demonstrate an oxidation-reduction reaction that effectively illustrates the reduction of silver ions to silver metal.
Materials:
250mL Erlenmeyer flask
3 150mL beakers
500mL Florence/boiling/round bottom flask
50mL beaker
heating plate/mantle
100mL graduated cylinder
Reagents:
0.1M Ammonium nitrate (NH4NO3)
0.1M Silver nitrate (AgNO3)
Dextrose
Ethanol (EtOH)
Fructose
Tartaric acid
Sodium hydroxide (NaOH)
Hazards and PPE:
Silver nitrate is toxic and contact with skin should be avoided.
Wear approved safety goggles and gloves.
Protocol:
Preparation
Solution A
Dissolve 2.5g of dextrose and 2.5g of fructose to 50mL DI H2O.
Add 0.6g tartaric acid.
Bring solution to a boil, cool, and pour into 100mL graduated cylinder.
Add 10mL EtOH.
Dilute to 100mL with DI H2O.
Solution B
Dissolve 4.0g AgNO3 in 50mL DI H2O.
Solution C
Dissolve 6.0g NH4NO3 in 50mL DI H2O.
Solution D
Dissolve 10g NaOH in 100mL DI H2O.
Thoroughly clean a 500mL Florence/boiling/round-bottom flask.
1 hour or less before demonstration, mix 15mL Solution B with 15mL Solution C in a clean 50mL beaker. This mixture is explosive and should not be prepared/stored ahead of time.
Demonstration
Add 30mL Solution A to flask.
Add the Solution B/C solution to flask.
Quickly add 30mL Solution D to flask and stopper it.
Mix flask with quick but gentle stirring motion. Be sure to cover the entire inner surface.
When finished swirling, immediately pour remaining solution down the drain and rinse with water.
Clean flask with dilute HNO3.
Additional Notes:
If no mirror forms, it is likely the flask was not clean.
Disposal:
Excess solution should be vacuum filtered via a Buchner funnel to allow silver to be saved for future AgNO3 solution.
Reactions:
Metallic silver (Ag) is formed when silver ions (from AgNO3) oxidize the aldehyde group of the glucose molecule.
Citations:
Summerlin, L. and Ealy, J. Chemical Demonstrations: A Sourcebook for Teachers, 1985.
