Section 13.2 Vocab and Questions
Why does the boiling point of a liquid vary depending on the atmospheric pressure?
Atmospheric pressure is usually what we understand for external pressure, and it is the total pressure of all the gases in the air.
Explain how evaporation lowers the temperature of a liquid.
During evaporation, the molecules with the highest kinetic energies are able to escape from the surface of the liquid. This results in a lower average kinetic energy of the remaining molecules, resulting in a lower temperature of the liquid.
What condition must exist for a liquid to boil?
Heat
In terms of kinetic energy, explain how a molecule in a liquid evaporates.
It must have a minimum kinetic energy to escape from the surface of the liquid and vaporize,that is turn from a liquid into a gas.
What factors help determine the physical properties of liquids?
Physical properties of a liquid are modeled using the interplay between the disruptive motions of liquid particles and the intermolecular attractions among the particles.
Determine the boiling point of ethanoic acid at 27 kPa and chloroform at 80 kPa.
The boiling point of ethanoic acid under this condition is approximately 73 Celsius degrees. The boiling point of chloroform at 80 kPa is roughly 53 Celsius degrees.
What is the relationship between the rate of evaporation of the liquid and the rate of condensation of the vapor in the container?
With constant vapor pressure, the rate of evaporation equals the rate of condensation.
Vapor pressure
a measure of the force exerted by a gas above a liquid in a sealed container; a dynamic equilibrium exists between the vapor and the liquid
Normal boiling point
the boiling point of a liquid at a pressure of 101.3 kPa or 1 atm
Vaporization
the conversion of a liquid to a gas or a vapor
Boiling point
the temperature at which the vapor pressure of a liquid is just equal to the external pressure on the liquid
Evaporization
vaporization that occurs at the surface of a liquid that is not boiling
