Question

Alcohol is more volatile than water, because :
A. Its boiling point is lower than water
B. It is an organic liquid
C. Its freezing point is lower than water
D. Its vapour pressure is ${\mathbf{2}}.{\mathbf{5}}$ times greater than water

Answer 1

- A liquid vaporizes when its vapour pressure becomes equal to atmospheric pressure.
- Water has $0.03$ atm vapour pressure at \;{25^0}$$$$C where alcohol has around $0.075 - 0.08$ atm vapour pressure at $$$$$$;{25^0}$$$$C$$.

Complete step by step solution:
Vapour pressure is defined as the pressure exerted by a vapour in thermodynamic equilibrium with its solid or liquid phase at a given temperature in a closed system.

The vapour pressure is an indication of a liquid’s evaporation rate. It relates to the tendency of particles to escape from the liquid(or solid). A substance with a high vapour pressure at normal temperature is often referred to as volatile.

- Water has $0.03$ atm vapour pressure at \;{25^0}$$$$C where alcohol has around $0.075 - 0.08$ atm vapour pressure at $$$$$$;{25^0}$$$$C$$.

So, alcohol is more volatile than water.

The correct option is (D).

Note: - If we increase the temperature, vapour pressure also increases.
- If any liquid has more vapour pressure it means it has lesser boiling points.