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Elements, Compounds and Mixtures

What is a Solution?

A solid or a gas dissolved in a liquid is called a solution.
A mixture of two miscible liquids is also called a solution.

The dissolved substance is called the solute.
The liquid used for dissolving is called the solvent.

What happens when a Solid Dissolves?

A solid dissolves when the particles of the solvent
are able to overcome the force of attraction
between the particles of the solid. An example is an
ionic compound dissolving in water. The
force of attraction between the ions is the ionic bond.

When an ionic solid dissolves, water molecules are
able to pull the oppositely charged ions apart and
separate them from each other. Each ion is surrounded
by water molecules and is free to move around in
the solution. The water molecules prevent the oppositely
charged ions from making bonds with each other.

What is a Saturated Solution?

Ionic compounds dissolve in water at a temperature
that is much lower than the melting point of the
compound. The amount of a solid that can dissolve
in a solvent is different for different solids.
The amount of a solid that can dissolve in a solvent
also changes with temperature. A solution that
has the maximum amount of a solid dissolved in it
is called a saturated solution. Crystallisation is
used to separate a solid from a saturated solution.

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