Phase Changes

What is a phase change?

A phase change is the reversible physical change that takes place when a substance changes from one state of matter to another.

A substance absorbs energy from its surroundings during a(n) _________ change.

A substance absorbs energy from its surroundings during an ENDOTHERMIC change.

As water freezes, it releases heat to its surroundings. Freezing is an example of a(n) _________ change.

As water freezes, it releases heat to its surroundings. Freezing is an example of an EXOTHERMIC change.

What is deposition?

Deposition is the phase change in which a substance changes directly from a gas to a solid without changing to a liquid first.

Dry ice can change directly from a solid to a gas without forming a liquid first. This process is an example of _____________.

Dry ice can change directly from a solid to a gas without forming a liquid first. This process is an example of SUBLIMATION.

The energy absorbed by one gram of ice as it melts is known as the _____________ for water.

The energy absorbed by one gram of ice as it melts is known as the HEAT OF FUSION for water.

The energy absorbed by one gram of water as it changes from its liquid phase into water vapor is known as the _____________________ for water.

The energy absorbed by one gram of water as it changes from its liquid phase into water vapor is known as the HEAT OF VAPORIZATION for water.

The phase change in which a substance changes from a gas into a liquid is called _____________.

The phase change in which a substance changes from a gas into a liquid is called CONDENSATION.

What happens to the temperature of a substance during a phase change?

The temperature of a substance remains constant during a phase change.

Vaporization is the phase change in which a substance changes from a(n) _______ into a(n) ________.

Vaporization is the phase in which a substance changes from a LIQUID into a GAS.

When liquid water freezes, the average kinetic energy of its molecules ___________, and the arrangement of molecules becomes more orderly.

When liquid water freezes, the average kinetic energy of its molecules DECREASES, and the arrangement of molecules becomes more orderly.

Sublimation

a. solid to gas

Vaporization

b. liquid to gas

Deposition

c. gas to solid

Circle the letter that describes the behavior of a substance during a phase change.

d. either absorbs or releases energy.

Freezing

d. liquid to solid

Condensation

e. gas to liquid

Melting

f. solid to liquid

Is the following sentence true or false? A gas absorbs energy as it changes into a liquid.

false

Is the following sentence true or false? The temperature at which a substance freezes is lower than the temperature at which it melts.

false

Is the following sentence true or false? Water molecules have a more orderly arrangement in ice than in liquid water.

true

Is the following sentence true or false? When water vapor collects above the liquid in a closed container, the pressure caused by the collisions of this vapor and the walls of the container is called vapor pressure.

true