Final answer:
The greater the temperature of a liquid, the weaker the surface tension, due to decreased intermolecular forces as molecular kinetic energy increases.
Step-by-step explanation:
The greater the temperature of a liquid, typically the weaker the surface tension becomes. This is because increasing temperature usually leads to an increase in the kinetic energy of the molecules, which weakens the intermolecular forces among them. For instance, at 20.0°C water has a greater surface tension than benzene because water molecules can form strong hydrogen bonds, whereas benzene molecules can only exhibit London dispersion forces. As the temperature rises, the enhanced molecular movement can overcome these bonds more easily, thus decreasing the surface tension.
Surface tension itself is the energy or work needed to increase the surface area of a liquid, a measure of the elastic force in the liquid's surface. Liquids with stronger intermolecular forces, like water, demonstrate higher surface tensions compared to those with weaker forces like benzene. When the temperature of a liquid increases, its molecules have more energy to move around and away from each other, reducing the net attractive forces at the surface and hence the elastic force measured as surface tension.