Substace change state

What happens when substances change state?

by Jurgen Von Schoettller

Ice, liquid water and water vapor are different states of the same substance.As liquid turns into ice or water vapor, the water molecules themselves do not change. What changes are the motion of the molecules and the amount of space between them.

The particles of a substance, even a solid, are always in motion.As a solid is heated, its particles gain energy and vibrate faster. The process in which a solid becomes a liquid is known as melting.

Eventually, the particles move slowly enough for the atraction between them to cause the liquid to become a solid. This process is called freezing.

When substance lose or gain energy, one of two things can happen to the substance: its temperature can change or its state can change. But both don´t happen at the same time. If you measure the temperature of boiling water, you will find that the temperature stays at 100C until all of the liquid has become a gas.

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