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Why the colour of potassium permanganate disappears if it is added to warm solution of ethanol?

When potassium permanganate reacts with ethanol, it releases nascent oxygen. ie, an atom of oxygen thus converting the ethanol to acetic acid. Initially colour disappears because coloured permanganate ions of potassium permanganate are consumed to oxidise ethanol.

C2H5OH (WITH ALKALINE KMnO4)  CH3COOH+H2O

2)When excess is added colour does not change because there is no more alcohol left and hence there is no reaction

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In case of excess use of potassium permanganate, the all available ethanol is oxidized into acetic acid. the remaining potassium permanganate is there, which gives the colour to the solution. 

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KMnO4 is pink in a solution without oxidizing reagents. Adding ethanol should change it to a brown solution. If adding ethanol can not change the solution to brown, then its environment is already acidic and will not reduce.

When potassium permanganate reacts with ethanol, it releases nascent oxygen. ie, an atom of oxygen thus converting the ethanol to acetic acid. Initially colour disappears because coloured permanganate ions of potassium permanganate are consumed to oxidise ethanol.

C2H5OH  (WITH ALKALINE KMnO4)    CH3COOH+H2O

When excess is added colour does not change because there is no more alcohol left and hence there is no reaction.
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An acid which can decolourise purple coloured potassium permanganate solution is sulfuric acid be citric acid carbonic acid or hydrochloric acid
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A warm solution of ethanol has much more capability to readily absorb more number of pottasium permanganate crystals that is more number of crystals get used up in oxidizing alcohol to acid: C2H5OH( In the presence of oxidizing agent and heat)-> CH3COOH
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