Table of Contents
Factors affecting surface tension of a liquid
(i) Effect of contamination:
If water surface has dust, grease or oil, the surface tension of water reduces. A small piece of camphor put in clear water dances vigorously due to decrease of surface tension of water.
(ii) Effect of solute:
(a) A highly soluble substance like sodium chloride increases the surface tension of water.
(b) A sparingly soluble substance like phenol or soap reduces the surface tension of water.
(iii) Effect of temperature:
The surface tension of liquids decreases with increase of temperature. The surface tension of a liquid becomes zero at a particular temperature, called critical temperature of that liquid.
For small temperature differences, surface tension decreases almost linearly as
σt = σ0 (1 – αt)
where σt and σ0 are the surface tensions at t°C and 0°C respectively, and α is the temperature coefficient of surface tension.