The oxidizing agent used is a solution of potassium
dichromate(VI), one test tube will be acidified with
hydrochloric acid, in other one the pH will be kept at about 7.
At both test tubes will be added potassium dichromate and
they will be heated to increse the reaction rate.
If oxidation occurs, then the orange solution containing the
dichromate(VI) ions will reduced to a green solution containing chromium(III) ions. In this reaction the ethanol is oxidised to acetaldehyde and finally to acetic acid.

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