Effect of temperature on surface tension an viscosity ?
http://physics.bu.edu/~duffy/py105/Viscosity.html
The effect of temperature on surface tension and viscosity can be explained using the principles of intermolecular forces.
Surface tension is the force that acts on the surface of a liquid, causing it to minimize its surface area. It is caused by the cohesive forces between liquid molecules. As temperature increases, the kinetic energy of the molecules also increases. This causes the molecules to move more vigorously and increases the overall molecular motion.
With increased molecular motion, the cohesive forces between the liquid molecules become weaker. As a result, the surface tension of the liquid decreases with increasing temperature. Therefore, at higher temperatures, liquids tend to have lower surface tension.
Viscosity, on the other hand, is a measure of a fluid's resistance to flow. It is caused by the internal friction between adjacent layers of molecules in a fluid. As temperature increases, the kinetic energy of the molecules increases. This leads to an increase in molecular motion and the weakening of intermolecular forces.
With weaker intermolecular forces, molecules are more able to move past one another, reducing the resistance to flow. Consequently, the viscosity of a liquid generally decreases with increasing temperature. This is why many fluids become less viscous and flow more easily at higher temperatures.
In summary, the effect of temperature on surface tension and viscosity can be explained by the increase in molecular motion and the weakening of intermolecular forces that occur with increasing temperature.