Page 77 - NCERT Science Class 10 English Medium

4.4.1 Properties of Ethanol

Ethanol is a liquid at room temperature (refer to Table 4.1 for the melting
and boiling points of ethanol). Ethanol is commonly called alcohol and
is the active ingredient of all alcoholic drinks. In addition, because it is a
good solvent, it is also used in medicines such as tincture iodine, cough
syrups, and many tonics. Ethanol is also soluble in water in all
proportions. Consumption of small quantities of dilute ethanol causes
drunkenness. Even though this practice is condemned, it is a socially
widespread practice. However, intake of even a small quantity of pure
ethanol (called absolute alcohol) can be lethal. Also, long-term
consumption of alcohol leads to many health problems.
Reactions of Ethanol
Reactions of Ethanol
Reactions of Ethanol
Reactions of Ethanol
Reactions of Ethanol
(i) Reaction with sodium –
Activity 4.6
Activity
Activity 4.64.6
Activity
Activity 4.6
4.6
–
2Na + 2CH CH OH → 2CH CH O Na + H
+
3 2 3 2 2
Teacher’s demonstration – (Sodium ethoxide)
n Drop a small piece of sodium, Alcohols react with sodium leading to the
about the size of a couple of evolution of hydrogen. With ethanol, the other
grains of rice, into ethanol
(absolute alcohol). product is sodium ethoxide. Can you recall which
n What do you observe? other substances produce hydrogen on reacting with
n How will you test the gas evolved? metals?
(ii) Reaction to give unsaturated hydrocarbon: Heating ethanol at
443 K with excess concentrated sulphuric acid results in the
dehydration of ethanol to give ethene –
Hot Conc.
CH − CH OH  → CH = CH + H O
3 2 H SO 2 2 2
2 4
The concentrated sulphuric acid can be regarded as a dehydrating
agent which removes water from ethanol.

How do alcohols affect living beings?
When large quantities of ethanol are consumed, it tends to slow metabolic processes
Do You Know? The individual may feel relaxed without realising that his sense of judgement, sense
and to depress the central nervous system. This results in lack of coordination,
mental confusion, drowsiness, lowering of the normal inhibitions, and finally stupor.

of timing, and muscular coordination have been seriously impaired.
Unlike ethanol, intake of methanol in very small quantities can cause death. Methanol
is oxidised to methanal in the liver. Methanal reacts rapidly with the components of
cells. It coagulates the protoplasm, in much the same way an egg is coagulated by
cooking. Methanol also affects the optic nerve, causing blindness.
Ethanol is an important industrial solvent. To prevent the misuse of ethanol produced
for industrial use, it is made unfit for drinking by adding poisonous substances
like methanol to it. Dyes are also added to colour the alcohol blue so that it can be
identified easily. This is called denatured alcohol.

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