Everything Science Grade 11

5.3 CHAPTER 5. THERMAL PROPERTIES AND IDEAL GASES

Volume

0

Temperature (K)

Figure 5.3: The volumeof a gas is directly proportional to its temperature, provided the pressure of the
gas is constant.

However, if this graphis plotted on a Celsius temperature scale (i.e.using◦C), the zero point of
temperature doesn’t correspond to the zero pointof volume. When the volume is zero, the temperature
is actually -273.15◦C (Figure 5.4).

Volume (cm

3 )

-273◦C 0 ◦C

0 K 273 K

Temperature

Figure 5.4: The relationship between volume and temperature, shown on a Celsius temperaturescale.

A new temperature scale, the Kelvin scale must be used instead. Since zero on the Celsius scale
corresponds with a Kelvin temperature of -273.1 5 ◦C, it can be said that:

Kelvin temperature (T) = Celsius temperature (t) + 273. 15

We can write:

T = t + 273

or

t = T− 273

Can you explain Charles’ law in terms of the kinetic theory of gases? When the temperature ofa gas
increases, so does the average speed of its molecules. The moleculescollide with the walls of the
container more often and with greater impact. These collisions will push back the walls, so that the