Question

A liquid is placed in an evacuated, sealed flask. When will the close system reach dynamic equilibrium?

A: When all of the liquid has evaporated to form a vapor
B: When liquid and vapor are present but evaporation stops
C: When the rate of evaporation equals the rate of condensation
D: When the volume of liquid equals the volume of vapor

Answer 1

Answer:

Correct option (c) - The ‘rate of evaporation’ equal to the ‘rate of condensation’.

Explanation:

• Evaporation is the ‘process of conversion’ liquid into vapour by applying the heat energy.

• Condensation of is process of conversion of vapours into liquids.

Dynamic equilibrium:

• The equilibrium vapor pressure is the vapor pressure measured when a ‘dynamic equilibrium’ exists in between the condensation and the evaporation.

For example: $\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \leftrightarrow | \mathrm{H}_{2} \mathrm{O}(l)$

• If a liquid is placed in an evacuated, sealed flask the equilibrium achieved while the ‘rate of evaporation’ equal to the ‘rate of condensation’.