Effect of Temperature on Surface Tension
Surface tension is inversely proportional to the temperature.
i.e. T ∝ 𝛾
We know that kinetic energy of molecules increases with increasing the temperature. Due to this increased kinetic energy, water molecules move quickly and weakening the cohesive forces that hold them together. Consequently, the surface tension of water decreases with increasing the temperature.
On the other hand, decreasing the temperature, slows down molecular movement of molecules, make the cohesive forces stronger and increases the surface tension.
At the critical temperature of a liquid, the surface tension becomes zero because at this point, the liquid and its vapor phase become indistinguishable, and the cohesive forces at the surface are completely overcome by the thermal motion of the molecules.
The relation between temperature and surface tension can be described by the following empirical equations-
𝛾 = 𝛾o − 𝑘 𝑇
where, 𝛾 is the surface tension at temperature 𝑇
𝛾o is the surface tension at a reference temperature (at or near the freezing point of the liquid)
𝑘 is a proportionality constant specific to the liquid.
