Chemical Concepts Demonstrated: Oxidation/reduction chemistry, variable oxidation states for transition metals
|Three solutions are used in the demo.
The test tube ends up having three or four layers inside of it. Yellow is at the top, blue is below that, green is below the blue, and violet is at the bottom.
Each one of the layers represents a different oxidation state of vanadium:
The oxidation reactions that take place in the demonstration are caused by oxidizing/reducing agents of various strengths. The resulting oxidation products separate from each other in the test tube. The reduction potentials are as follows:
|VO2+ to VO2+ (yellow to blue)||Eo = 1.0 V|
|VO2+ to V3+ (blue to green)||Eo = .33 V|
|V3+ to V2+ (green to violet)||Eo = -.26 V|
|V2+ to V||Eo = -1.18 V|