Question

Water in an earthenware gets cooled, but not when kept in a metal container. Explain.

Answer 1

Earthenware are porous. Water kept inside seeps out and wets the outer surface. Dry air outside helps in evaporation of this water. The latent heat of evaporation is taken from the pot and the water inside. During this process, the latent heat is absorbed by the water on surface to evaporate causing the cooling effect to the earthenware and the water inside.

While in metal container, there are no pours for this process to take place. Metals are good conductor, so they conduct to make temperature of water inside it equal to the temperature of surrounding.