Question

Liquid A has a vapor pressure of 7.37 kPa at 40C. Liquid B has a vapor pressure of 18.04kPa at 40C. Which liquid would evaporate faster at 40C? Explain your answer.

Answer 1

Answer:

Liquid B because of its higher vapor pressure due to the fact that evaporation rate is directly proportional to vapor pressure

Explanation:

The vapor pressure of  liquid at equilibrium is a function to the liquid's rate of evaporation. The evaporation rate and hence the vapor pressure is a measure of the propensity of the particles  of the liquid to leave the surface of the liquid and exist as vapor directly above the liquid. As high evaporation rate leads to high vapor pressure, a liquid with a higher vapor pressure will evaporate faster than one with a lower vapor pressure at the same temperature and pressure.

Therefore, liquid B with a vapor pressure of 18.04 kPa at 40° C will evaporate faster than liquid A with a lower vapor pressure of 7.37 kPa at the same 40°C.