19.3 - Boyle’s and Charles’ gas laws
In this section we take a macroscopic view of ideal gases to discuss their overall
properties. Several laws state the relationship among macroscopic properties such as
pressure, volume, temperature, and the amount of gas (number of molecules). We start
here with Boyle’s and Charles’ laws.
Boyle’s law is named for Irish scientist Robert Boyle, who in 1662 discovered that the
absolute pressure of a fixed amount of gas at a constant temperature is inversely
proportional to its volume. To put it another way, if you decrease the volume of a gas,
its pressure increases proportionally. Boyle’s law is stated in Equation 1: The product of
the initial pressure and volume of a gas equals the product of its final pressure and
volume.
Jacques Charles, a Frenchman who worked a century later than Boyle, also studied
gases. One way to state Charles’ law is that for a fixed amount of gas at a constant
pressure, the ratio of its volume to its absolute temperature remains constant. You see
this in Equation 2 using the initial and final volumes and temperatures of a gas.
These gas laws are empirical; that is, they are determined to be true through
experiment and measurement rather than being derived from other laws.Boyle’s law
PiVi = PfVf
P = absolute pressure
V = volume
Temperature, quantity of gas constant
Charles' law
V = volume
T = Kelvin temperature
Pressure, quantity of gas constant
(^362) Copyright 2000-2007 Kinetic Books Co. Chapter 19