Jacques Charles: 1746-1823 Balloonist, noticed relation between temperature and volume At constant P: V=kT or V/T=k More commonly V 1 /T 1 =V 2 /T 2.

Jacques Charles: 1746-1823

Balloonist, noticed relation between temperature and volume

At constant P: V=kT or V/T=k

More commonly V1/T1=V2/T2

Charles noticed that no matter what the starting volume was, if P is constant and he increased T, the V also increased

Graphing the relationship between V and T produces a straight line

This is a direct proportion

Note that if you extend the lines, you can reach a temperature at which volume is ZERO!

1824-1907 Extended work of

Joule, Charles and others to use gas as thermometer

Gas volume changes 1/273 for every degree change

Kelvin scale: based on T at which volume of gas is zero

To use temperature in gas law equations, you MUST convert the temperature to Kelvins› Otherwise, you may end up calculating a

negative volume! 0 K = -273.15 oC To go from oC to K, add 273.15 To go from K to oC, subtract 273.15

A 2.0 L sample of air is collected at 298 K then cooled to 278 K. The pressure is held constant at 1.0 atmo. What is the new volume of the air?

A sample of gas at 15 oC has a volume of 2.58 L. The temperature is then raised to 38 oC. What is the new volume?

A child blows a soap bubble at 28 oC with a volume of 1.0 L. As the bubble rises, it encounters a pocket of cold (18 oC air). What is the new volume of the bubble?

Gas volume has been used as a way to measure temperature (gas thermometer). If a gas has a volume of 0.675 L at 35 oC and 1 atmo P, what is the temperature of a room if the gas has a volume of 0.535 L in the room (at 1 atmo P)?