The ideal gas law is a combined set of gas laws that is a thermodynamic equation that allows us to relate the temperature, volume, and number of molecules (or moles) present in a sample of a gas. The ideal gas law was discovered by physicist and engineer Benoît Paul Émile Clapeyron (seen on the right) in 1834. You may have seen the equation PV = nRT in your classes before. This is the ideal gas law equation, and it is the use of this equation that helps us understand and control the behavior of gases we use in everyday objects such as soda cans, scuba tanks, weather balloons, and car airbags.

Source: Benoit Clapeyron, Ahellwig, Wikimedia Commons

Source: Green soda can, Vectorscape

Source: Curtainairbags, Brandweer Dodewaard, NL

Source: Yonaguni Ruins Scuba, Gorgo, Wikimedia Commons

Source: 2006 Ojiya balloon festival, Kropsoq, Wikimedia Commons

Exploring the Ideal Gas Law

Source: Gas Properties, The University of Colorado - Boulder

• In the top right corner of the simulation, set the constant parameter to "None."
• Move the pump handle up and down once.
• Wait 10–15 seconds for the gas particles to evenly distribute through the chamber.
• Look at the value on the pressure gauge.
• Move the pump handle up and down again.

What happens to the value of the pressure when the number of particles increases? Interactive popup. Assistance may be required.

Check Your Answer

The pressure increases when the number of particles increases.

• Use the "Heat Control" slider to increase the temperature of the gas to 400K.
• Observe the temperature and the pressure gauge.

What happens to the value of the pressure as the temperature of the gas rises? Interactive popup. Assistance may be required.

Check Your Answer

The pressure rises as the temperature rises.

• Use the "Heat Control" slider to decrease the temperature of the gas to 200K.
• Observe the temperature and the pressure gauge

What happens to the value of the pressure as the temperature decreases? Interactive popup. Assistance may be required.

Check Your Answer

The pressure decreases as the temperature decreases.

• Use the "Heat Control" slider to return the gas to 300K.
• Click and drag the handle on the left side of the chamber slowly to the left.

What happens to the values of the temperature and pressure as you increase the volume? Interactive popup. Assistance may be required.

Check Your Answer

Temperature and pressure decrease as the volume increases.

• Click and drag the handle on the left side of the chamber to the right.

What happens to the values of the temperature and pressure as you decrease the volume? Interactive popup. Assistance may be required.

Check Your Answer

Temperature and pressure increase until the lid is blown off the chamber. (If the lid didn't pop off, move the slider to the right again.)

• Click "reset."
• Move the pump handle up and down two times.
• Wait 10–15 seconds for the gas particles to evenly distribute through the chamber.
• In the top right corner of the simulation, set the constant parameter to "Pressure."
• Pump the handle again.

What happens to the volume when the number of particles increased?

Check Your Answer

The volume increased when the number of particles increased.

• Slide the lid open to allow about 100 of the particles to escape. (You can see how many particles there are on the right side of the window in the box called "Gas in Chamber.")

What happens to the volume when the number of particles decreased?

Check Your Answer

The volume decreased when the number of particles decreased.

• Use the "heat control" slider to increase the temperature of the gas.

What happens to the volume as the temperature rises?

Check Your Answer

The volume increases as the temperature rises.

• Use the "heat control" slider to decrease the temperature of the gas.

What happens to the volume as the temperature falls?

Check Your Answer

The volume decreases as the temperature falls.