A beaker half-filled with water is left uncovered on a laboratory bench at
CHEMISTRY · Single correct · CBSE · Chemistry · Matter in Our Surroundings · Matter in Our Surroundings
Problem
A beaker half-filled with water is left uncovered on a laboratory bench at 25∘C. Which statement best explains why the evaporation of the water is effectively irreversible under these conditions?
(a) The entropy of the system must continue to increase, so the reverse process of condensation is thermodynamically impossible.
(b) Condensation would require the temperature to reach the normal boiling point (100∘C); below that temperature, condensation cannot occur.
(c) Water vapour escapes into the surrounding air, so the partial pressure of H2O never reaches its equilibrium value and condensation cannot keep pace with evaporation.
(d) For condensation to occur in an open vessel, the partial pressure of water vapour would have to exceed 1atm, which is impossible under these conditions.