Properties of Liquids Quiz

Properties of Liquids

• Liquids have a definite volume, but an indefinite shape, taking the shape of their containers to the level they fill.
• They are denser than gases, but less dense than solids.
• Liquid particles are in constant motion, but are closer together than those in a gas.
• Attractive forces between particles in a liquid are stronger than between particles of a gas, due to intermolecular forces of attraction.
• Liquids are more ordered than gases due to stronger intermolecular forces and lower mobility of liquid particles.

Vaporization and Evaporation

• Vaporization is the process by which a liquid changes to a gas.
• Evaporation is the process by which molecules on the surface of a liquid break away and go into the gas phase.
• Molecules on the surface of a liquid are held less tightly than those in the interior, allowing the most energetic molecules to break away into the gas.
• Evaporation is explained in terms of the energy that the molecules on the surface of the liquid have.

Evaporation in Open and Closed Containers

• In an open container, evaporation continues until all of the liquid enters the gas phase.
• Most molecules that escape into the vapor phase do not collide with the surface of the liquid and return to the liquid phase, but instead diffuse through the gas phase away from the container.
• In a closed container, the volume of the liquid decreases for some time, and then remains unchanged, as the vapor cannot escape.
• As more molecules leave the liquid, more gaseous molecules collide with the container walls, with each other, and with the liquid surface, and return to the original liquid state.

Condensation and Dynamic Equilibrium

• Condensation is the process of a vapor returning to the liquid state.
• Evaporation and condensation are opposing processes.
• In a closed container, the rate of condensation increases as the number of gaseous molecules increases, eventually reaching dynamic equilibrium.
• At dynamic equilibrium, the rates of condensation and evaporation become equal, and the number of gaseous molecules above the liquid remains constant.
• The vapor pressure of a liquid is the partial pressure of its vapor in dynamic equilibrium with its liquid.