2.17. Changes of State http://www.ck12.org
again.
Q:Why is energy always involved in changes of state?
A:The energy of particles of matter determines the matter’s state. Particles of a gas have more energy than particles
of a liquid, and particles of a liquid have more energy than particles of a solid. Therefore, in order for matter to
change from a solid to a liquid or from a liquid to a gas, particles of matter must absorb energy. In order for matter
to change from a gas to a liquid or from a liquid to a solid, particles of matter must lose energy.
Summary
- A change of state occurs whenever matter changes from one state to another. Changes of state are physical
changes in matter. They are reversible changes that do not change matter’s chemical makeup or chemical
properties. - Processes involved in changes of state include melting, freezing, sublimation, deposition, condensation, and
evaporation. - Energy is always involved in changes of state. Particles of matter either absorb or lose energy when matter
changes from one state to another.
Explore More
Take the changing states quiz at the following URL. Be sure to check your answers.
http://www.bbc.co.uk/bitesize/ks2/science/materials/changing_states/quiz/q69393075/
Review
- Define change of state, and give an example.
- Identify processes that change matter to a liquid state.
- Why must energy be absorbed to change a liquid to a gas?