In this experiment a number of reactions are performed on a variety of organic c

Question

In this experiment a number of reactions are performed on a variety of organic compounds in order to identify their functional groups. This exercise is designed to remind you of some oxidation and reduction theory that will be encountered in the experiment. When ethanol is heated with acidified potassium dichromate it gets oxidised and forms ethanoic acid. The two half-equation skeletons are given below. Balance this reaction using the approach learnt in Unit 24: i. Balance all atoms other than O and H ii. Balance O using H_2O iii. Balance H using H^+ iii. Balance the charge using e^- Multiple each half-equation by an appropriate factor to ensure the number of electrons in each is the same. Add the half-equations together and cancel where necessary. Oxidising agents (or oxidants) are reduced in a redox reaction because they GAIN the electrons produced by the species being oxidised. Similarly reducing agents or reductants are oxidised in a redox reaction because they

Explanation / Answer

The overal reaction is

3 CH3CH2OH + 2 Cr2O72- +16 H+   ------> 3 CH3COOH + 4 Cr3+ +11 H2O

THe oxidation of primary alcohol i.e. ethanol to acetic acid is done by Cr(VI) in the acedic medium,

In this process Cr(VI) loose its electron and becomes Cr(III). The oxidation state of Cr changed from 6 to 3. THiat means it got reduced,

Oxidant: who lose elcectrons/ oxygen to the other substance . IN this case,Cr(VI) or Cr2O72- is oxidizing agent or Oxidant

Reductnat: Who accept electrons/Oxigen from oxidant. In the above example, CH3CH2OH is the reductant. Ethanol accept oxygen from chromium salt and becomes acetic acid.

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