Question

Comment on the statement ‘evaporation is a surface phenomenon’.

Answer 1

1. Particles at the Surface Escape:

   • In a liquid, particles at the surface are loosely bound compared to those inside.
   • When surface particles gain enough energy (e.g., from heat), they overcome the forces of attraction and escape into the air as vapor.

2. No Boiling Required:

   • Unlike boiling, evaporation happens at any temperature below the boiling point and does not require heating the entire liquid.
   • Only the particles at the surface participate in evaporation.

3. Examples:

   • Water in a glass slowly evaporates from the surface over time.
   • Sweat on the skin evaporates, cooling the body.