The table given below shows the change in length (expansion or contraction) when a

unit length (1 m or 1 ft, etc) of a material is warmed or cooled one Celsius degree.

This fractional change in length for a temperature rise of 1° is called the COEFFICIENT

OF LINEAR EXPANSION. For example, 1.00 m of steel increases 2.00 E – 5 m when it is

warmed 1° C. Consider a bridge 1.00 E 3 m long. For every increase in temperature

of 1° C every meter of the bridge increases by 2.00 E‑5 m. This results in a total

of 2.00 E – 2 m increase in length. When the temperature increases by 10.0 degrees

the increase in length will be 10 times as much. And between winter and summer,

a change of temperature of as much as 40.0° may take place, increasing the length

of this bridge by 0.800 m (1.00 E 3 m x 40.0° C x 2.00 E – 5 /° C ). If the engineer did not

allow for expansion, the force exerted by this expansion (or contraction in winter)

would result in buckling of steel girders.

The behavior of substances as the temperature changes gives us another

means of identifying them. Solids melt and liquids boil; if they are pure substances,

they melt or boil at definite temperatures. But whether or not these changes occur,

matter in all states expands or contracts with a change in temperature, and the extent

of this change can be measured. Melting points, boiling points, and the amount of

expansion or contraction are three properties useful in distinguishing among substances,

but some substances neither melt nor boil. Still other properties are needed to distinguish

between them.