All substances are composed of molecules and atoms that are actually moving at all times. Phase is caused by the force of the attraction between a substance's particles.
Substances can change their phase when heat energy or pressure is added or removed. Vaporization (or evaporation) is the change from liquid to gas. This happens when a liquid is heated to its boiling point. The less pressure there is on a liquid, the lower the boiling point. Water boils at 212°F (100°C) at sea level, but on top of a mile-high mountain, it boils at 203°F (95°C).
The condensation point is the temperature at which a gas can become a liquid again. It's the same temperature as the boiling point. Freezing is the change of state from a liquid to a solid by removing enough energy. Melting is the change back to liquid. Some substances can change directly from a solid to a gaseous state. This is called sublimation.
The change from a solid to a gas is called
A
boiling.
B
sublimation.
C
melting.
D
freezing.
1 answer