What are the factors affecting the surface tension of a liquid?

Explanation

(i) The presence of any contamination or impurities considerably affects the force or surface tension depending upon the degree of contamination.
(ii) The presence of dissolved substances can also affect the value of surface tension. For example, a highly soluble substance like sodium chloride (NaCl) when dissolved in water (`H_(2)O`) increases the surface tension of water. But the sparingly soluble substance like phenol or soap solution when mixed in water decreases the surface tension of water.
(iii) Electritication affects the surface tension. When a liquid is electrified, surface tension decreases. Since external force acts on the liquid surface due to electrification, area of the liquid surface increases which acts against the contraction phenomenon of the surface tension. Hence, it decreases.