14.2 Gas Laws
14.2 Gas Laws
Lesson Objectives
- Use Boyle’s law to calculate pressure-volume changes at constant temperature.
- Use Charles’s law to calculate volume-temperature changes at constant pressure.
- Use Gay-Lussac’s law to calculate pressure-temperature changes at constant volume.
- Use the combined gas law to solve problems in which pressure, volume, and temperature all change.
- Use Avogadro’s law to calculate volume-number of moles changes at constant temperature and pressure.
Lesson Vocabulary
- Avogadro’s law
- Boyle’s law
- Charles’s law
- Combined gas law
- Gay-Lussac’s law
Check Your Understanding
Recalling Prior Knowledge
- How does the pressure of a confined gas respond when its volume is decreased?
- How does the pressure of a confined gas respond when its temperature is increased?
- How does the pressure of a confined gas respond when more gas is added to the container?
According to the kinetic-molecular theory of gases, the volume of gas particles is negligible and any attractive forces
between particles can be ignored. When these simplifying assumptions hold true, a series of simple empirical rela-
tionships called the gas laws, which relate pressure, volume, amount, and temperature, can also be mathematically
derived.
Boyle’s Law
Robert Boyle (1627-1691), an English chemist (Figure14.7), discovered that doubling the pressure of an enclosed
sample of gas while keeping its temperature constant caused the volume of the gas to be reduced by half.Boyle’s
Lawstates that the volume of a given mass of gas varies inversely with the pressure when the temperature is kept
constant. An inverse relationship means that as one variable increases in value, the other variable decreases.
Mathematically, Boyle’s Law can be expressed by the following equation: