Gay-Lussac's Law: Gas Pressure and Temperature Relationship

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: The Ideal Gas Law and the Gas Constant

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:05 Temperature and…
  • 1:57 Gay-Lussac's Law
  • 3:04 Practice Question 1
  • 4:05 Practice Question 2
  • 5:49 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Kristin Born

Kristin has an M.S. in Chemistry and has taught many at many levels, including introductory and AP Chemistry.

You may know that you aren't supposed to put an aerosol can in a fire because it could explode, but do you know why? In this lesson, we will explain Gay-Lussac's law, which shows the relationship between the temperature and pressure of a gas.

Temperature and Pressure Relationship

Johnny Dalton is enjoying his day at the beach on Ideal Island, the place where all gases behave ideally. What makes them behave so ideally? Ideal gas particles move rapidly and randomly, they don't lose energy when they collide, and they do not have any intermolecular forces. This means that when two ideal gas particles get near each other, they are not attracted to each other like real gas particles may be.

As he lays his towel out and gets his sunblock out, he notices a warning on the back of the aerosol can: Contents under pressure; do not heat. Why would heating this aerosol can be a cause for warning? Johnny thinks for a minute and then recalls some of the ideas of kinetic molecular theory. He remembers that as the temperature of a gas increases, the gas particles move faster and faster. After all, temperature is really just a measure of the average kinetic energy of the particles. Also, when gas particles are moving quickly, they hit the insides of their container more frequently. Finally, because pressure is just a measure of the force of the particles hitting the inside of the container, the more times it hits the inside of the container, the higher the pressure will be!

As heat rises, particles in a gas move faster, increasing pressure.
Temperature Increases Particles Move Faster

Now, the container that is holding these particles may not be able to withstand those high amounts of pressure. If the pressure inside of the container exceeds the limits of the container, an explosion could occur.

If you live in cold climates, you may notice that the pressure in your car's tires decreases as it gets colder. This is because the air particles inside the tires are colder and moving slower. They don't hit the inside walls of the tires as frequently, and the pressure in your car's tires decreases.

Gay-Lussac's Law

This relationship between temperature and pressure is known as Gay-Lussac's law. It states that if the volume of a container is held constant as the temperature of a gas increases, the pressure inside the container will also increase. As with the other gas laws, this one can be represented in the form of an equation:

P1/T1 = P2/T2

Recall that we use 1s and 2s to indicate the quantities before (1s) and after (2s) a change has taken place. Also, note that the units for pressure do not matter, as long as they are the same throughout the entire equation. The units for temperature must be Kelvins or the equation will not work. This is because the Kelvin scale is an absolute scale - it doesn't go negative. Finally, this equation only works for an ideal gas. Most gases that surround you and me behave very much like ideal gases, so we can use this equation as an approximation for the gases we encounter.

Use this equation for calculating the relationship between pressure and temperature.
Gay Lussacs Law Equation

Practice Question 1

Let's say you are making dinner using a pressure cooker with an initial internal pressure of 1 atmosphere and an internal temperature of 100 degrees Celsius (or 373 K). Assuming the volume does not change and the gas behaves ideally, what will the pressure inside the container be if the temperature is raised to 200 degrees Celsius (or 473 K)?

To solve this, you will need to make sure you are using the Kelvin temperatures. Substituting the numbers into the correct locations in the equation given to us:

1 atm / 373 K = P2 / 473 K

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account