A small drop of water assumes an almost spherical form on a Teflon TM surface.
Explain why.
Surface tension of water accounts for the spherical shape unless there are adhesive forces between water and the the surface on which it sits. Teflon has little attraction for almost any other substance.
The small drop of water assumes an almost spherical form on a Teflon surface due to a phenomenon called surface tension. Surface tension is a property of liquids that arises from the cohesive forces between molecules at the surface of the liquid.
When a drop of water is placed on a Teflon surface, the Teflon is hydrophobic, meaning it repels water. This hydrophobic nature of Teflon creates a minimal contact area between the water and the surface, which in turn minimizes the interaction between water molecules and the Teflon molecules.
The cohesive forces between the water molecules are much stronger compared to the weak adhesive forces between the water and Teflon. As a result, the water molecules tend to pull themselves together, creating a spherical shape that minimizes the surface area exposed to the Teflon surface. The surface tension of the water provides this pulling force, which allows the drop to retain its spherical shape.
In summary, the small drop of water assumes a nearly spherical form on a Teflon surface due to the hydrophobic nature of Teflon, which minimizes the contact area and weakens the adhesive forces between water and Teflon. The cohesive forces between water molecules, along with the surface tension, cause the drop to pull itself into a spherical shape.