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Let us now see the physical and chemical properties of ethanol and its uses:
a) Physical properties of ethanol ($$C_2H_5OH$$):
• It is a colourless liquid, has a pleasant smell and a burning taste.
• It is a volatile liquid with the boiling point at $$780°C$$ ($$351K$$), which is far above that of its corresponding alkane, i.e. ethane (Boiling Point = $$184 K$$).
• It is completely miscible in water irrespective of its proportions.

b) Chemical properties of ethanol ($$C_2H_5OH$$):

1. Dehydration (Loss of water):

There is a loss of water molecules when ethanol reacts with concentrated sulphuric acid ($$H_2SO_4$$) at $$443K$$, i.e. dehydrated to form ethene.

Therefore, the chemical reaction is represented as
$$CH_3CH_2OH \xrightarrow [443K]{Conc H_2SO_4} CH_2=CH_2 + H_2O$$
Ethanol                                         Ethene               Water

2. Reaction with sodium:

The reaction of sodium metal with ethanol produces sodium ethoxide and hydrogen gas.

Therefore, the chemical reaction is represented as
$$2CH_3CH_2OH + 2Na \rightarrow 2C_2H_5ONa + H_2$$
Ethanol                 Sodium             Sodium          Hydrogen
ethoxide           gas

3. Oxidation:

Ethanoic acid is formed when ethanol is oxidised with alkaline potassium permanganate ($$KMnO_4$$) or acidified potassium dichromate ($$K_2Cr_2O_7$$).

The colour change occurs during this reaction where the orange colour of  $$K_2Cr_2O_7$$ turns green. This reaction can be used for the identification or confirmation of the alcohol group.

4. Esterification:

Alcohol in reaction with a carboxylic acid produces a compound having a fruity odour. This compound is referred to as an ester, and the reaction is known as esterification.

Ethanol on reaction with ethanoic acid in the presence of concentrated sulphuric acid ($$H_2SO_4$$) forms ethyl ethanoate (an ester compound).

$$CH_3CH_2OH + CH_3COOH \xrightarrow {Conc H_2SO_4} CH_3COOC_2H_5 + H_2O$$
Ethanol                  Ethanoic acid                              Ethyl ethanoate

5. Dehydrogenation:

The process of dehydrogenation occurs when vapours of ethanol pass over hot copper ($$Cu$$) at $$573K$$. In this reaction, copper is used as a catalyst. Dehydrogenation of ethanol forms acetaldehyde ($$CH_3CHO$$).

$$CH_3CH_2OH \xrightarrow [573K]{Cu} CH_3CHO + H_2$$
Ethanol                                Acetaldehyde   Hydrogen
gas

6. Combustion:

Ethanol is a volatile and highly inflammable liquid. Carbon dioxide ($$CO_2$$) and water are formed when ethanol reacts with oxygen (O_2\).

$$CH_3CH_2OH + 3O_2 \rightarrow 2CO_2 + 3H_2O$$
Ethanol                    Oxygen    Carbon    Water
dioxide

c) Uses of ethanol:
• It is used in medical wipes as an antiseptic.
• It is used as an anti-freeze in automobile radiators.
• It effectively kills microorganisms like bacteria, fungi, etc., as it is used in hand sanitisers.
• It is used as an antiseptic to sterilise wounds in hospitals.
• It is used as a solvent for drugs, oils, fats, perfumes, dyes, etc.
• It is used in the preparation of methylated spirit (mixture of $$95%$$ of ethanol and $$5%$$ of methanol), rectified spirit (mixture of $$95.5%$$ of ethanol and $$4.5%$$ of water), power alcohol (mixture of petrol and ethanol) and denatured spirit (ethanol mixed with pyridine).
• It is used to enhance the flavour of food extracts, for example, vanilla extract.
• It is a common food flavour made by processing vanilla beans in a solution of ethanol and water.