|Demonstration Experiment on Video|
Objective: Mechanism of an Oscillating Reaction
Ferroin solution: 0.35 g of ferrum sulfate heptahydrate and 0.88 g of 1.10-phenanthroline hydrochloride are dissolved in 35 ml dist water. The solution is made up to 50 mL with dist. water.
Hazards and safety precautions:
Safety goggles and protective gloves must be worn. Effective ventilation!
Four solutions are prepared:
Solution A: 6.75 g of KBrO3 in 80 mL of dist. water
Solution B: 15.6 g of malonic acid in 100 mL of dist. water
Solution C: 1.3 g of KBr in 70 mL of dist. water
Solution D: 14 mL of conc. H2SO4 in of 65 mL dist. water. The mixture is allowed to cool to room temperature.
The four solutions are poured into a crystallizing dish containing 400 mL of dist. water while stirring on a magnetic stirrer. After the yellow-brown color (bromine) has disappeared, 2 mL of ferroin solution are added to the mixture.
Ferroin-indicator added creates a red color. After approximately 75 seconds the color of the solution turns to a blue, that will disappear after a short time and a red color will appear again. Thus the color oscillates between red and blue.
Video clip (Download RealPlayer .rm Datei)
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Index of Lecture Experiments