What is the Ideal Gas Law?

A Fundamental Equation in Chemistry and Physics

The Ideal Gas Law describes the relationship between four key variables that define the state of a gas: pressure (\({P}\)), volume (\({V}\)) , temperature (\({T}\)), and the number of moles of gas (\({n}\)).

The law assumes that the gas behaves ideally, meaning the gas particles do not interact with each other except for elastic collisions, and they take up no volume themselves.

The Ideal Gas Law is expressed as: \[{P}{V} = {n}{R}{T}\] Where
  • \({P}\) is the pressure of the gas (in units such as atmospheres, Pa, etc.)
  • \({V}\) is the volume of the gas (in liters or cubic meters)
  • \({n}\) is the number of moles of gas
  • \({T}\) is the temperature of the gas (in Kelvin) \({R}\) is the ideal gas constant, typically 8.314 \({J/ mol • K}\)

Remember

Two key details to keep in mind when it comes to the Ideal Gas Law.

  • Direct and Inverse Relationships: The Ideal Gas Law combines all the major gas laws (Boyle’s, Charles’s, and Gay-Lussac’s) into one equation that relates pressure, volume, temperature, and the number of moles of gas.

  • Temperature in Kelvin: As with all gas laws, temperature must be measured in Kelvin to maintain the correct proportional relationships.er

Why the Ideal Gas Law Is Important

The Ideal Gas Law is critical for anyone studying physics, chemistry, or engineering. It provides a way to calculate the behavior of gases in different conditions, making it useful in everything from chemical reactions to understanding how engines work. Learning the Ideal Gas Law will give you a strong foundation in understanding gas behavior.
People floating in a hot air balloon over Paris

Real-World Applications of the Ideal Gas Law

  • Airbags

    The Ideal Gas Law is used to determine how much gas needs to be generated in an airbag for it to inflate properly during a collision. By controlling the number of moles of gas produced in a chemical reaction, engineers can control the volume and pressure to ensure safety.

  • Breathing

    The Ideal Gas Law helps explain how gases behave in your lungs. As you inhale and exhale, the pressure, volume, and temperature of the gases change, allowing oxygen to move into your blood and carbon dioxide to move out.

  • Weather Balloons

    As weather balloons rise through the atmosphere, the pressure decreases, causing the balloon to expand. The Ideal Gas Law helps predict how much the balloon will expand as the atmospheric pressure drops and temperature changes.

Our Chemistry course

Additional products

Related Topic

Charles's Law

The Relationship Between Temperature and Volume in Gases
#LearnMore
People in a hot air balloon floating over Paris