How to discuss reaction of carboxylic acids with oxidizing agents?

[jane297jeng]

Test Compounds--------Observation/ Color
Acetic Acid----------------Violet Color
Lactic Acid-----------------Black Substance Settled Below
Tartaric Acid---------------Dark Violet, Blue, tiny particles are formed
Citric Acid------------------Dark Violet Color
Benzoic Acid--------------Violet Color
Oxalic Acid-----------------Violet Color, White particles floats above the solution

and i think the oxidizing agent is permanganate from potassium permanganate (KMnO4)..

we used 0.1% KMnO4

How do i dicuss these results(their color formation)?

Thanks!