When you have finished this page,
try the Liquids Quiz.
A liquid is a state of matter that
has a definite size or volume but not a definite shape. A liquid takes the shape
of the container in which it is held and presses on the container in the same
amount in all directions. The molecules in a liquid are closer together than
those in a gas but not as close together as those in a solid. The molecules
in solids are in a fixed position but those in liquids move around more.
Although molecules in a liquid hang
together through forces called cohesion, The molecules at the surface of a liquid
can also jump off from the liquid into the surrounding air in a process called
evaporation. The rate of evaporation depends on the humidity of the air, how
much of the surface of a liquid is exposed to the air, and the temperature.
Most liquids expand or spread out
when heated and contract when cooled. When a liquid is heated to its boiling
point, it changes to a gas. When a liquid is cooled to its freezing point, it
becomes a solid. The melting point and boiling point are two ways to tell what
a liquid is as liquids can differ in these measures. Heating a mixture can be
used to separate out the parts of a mixture.
One property of liquids is diffusion.
Diffusion is when the movement of a concentration in one part of a liquid that
is higher to a part of the substance where the concentration is lower.
Liquids are also difficult if not
impossible to compress.
Liquids also exert buoyancy on other
objects placed within the liquid. The amount of buoyancy is equal to the amount
of the liquid that is pushed out of place when the object is placed in the liquid.
