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Elements, Compounds and Mixtures

Changing from a Solid to a Liquid to a Gas by Heating.

Any substance may exist as a solid, liquid or gas.

and Cooling a Solid.

If a solid is heated enough, it will melt to become a liquid.
The temperature at which it melts is called its melting point.
If the liquid is then cooled, it will freeze to become a solid again.
The temperature at which it freezes is called its freezing point.
The melting point and the freezing point
is the same for the same substance.

Sometimes a heated solid will turn into a gas
without first becoming a liquid. This is called sublimation.
Examples of solids that sublime are iodine and carbon dioxide.

and Cooling a Liquid.

If a liquid is heated enough, it will boil to become a gas.
The temperature at which it boils is called its boiling point.
If the gas is then cooled, it will condense to become
a liquid again. A gas will condense at its boiling point.

A liquid can also become a gas by evaporation.
This happens at a temperature below its boiling point.

Interconverting between a Solid, Liquid and Gas.

The figure below shows interconverting
from one state to another by heating or cooling.
Red arrows involve heating, blue arrows involve cooling.

Interconverting Solid to Liquid to Gas by using Heat

The state of a substance (whether it is solid, liquid or gas)
depends on its temperature, the RFM of the particles
and the forces of attraction between the particles.

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