Thermodynamics part 1: Molecular theory of gases | Physics | Khan Academy

TL;DR

Pressure in gases is caused by the molecules of the gas constantly bumping into each other and into the walls of the container, resulting in a change in momentum. Pressure can be calculated using the formula: Pressure x Volume = Constant.

Transcript

After all the work we've been doing with fluids, you probably have a pretty good sense of what pressure is. Now let's think a little bit about what it really means, especially when we think about it in terms of a gas in a volume. Remember, what was the difference between a gas and a liquid? They're both fluids, they both take the shape of their con... Read More

Key Insights

• 🫢 Pressure in gases is a result of constant collisions between gas molecules.
• 💥 The force exerted by these collisions can be measured as pressure.
• 🔇 Pressure and volume in a gas are inversely related: increasing volume decreases pressure, and decreasing volume increases pressure.
• ☺️ The formula pressure x volume = constant is used to calculate pressure in gases.
• 🫢 Gas pressure can be affected by changes in the number of gas molecules or their average kinetic energy.
• 🫢 Increasing the number of gas molecules or their average kinetic energy can increase the pressure of the gas.
• 🫢 Decreasing the number of gas molecules or their average kinetic energy can decrease the pressure of the gas.

Questions & Answers

Q: How is pressure in gases generated?

Pressure in gases is generated by the constant collisions of gas molecules with each other and the walls of the container. These collisions result in a change in momentum and the exertion of force.

Q: How can pressure be calculated in gases?

Pressure in gases can be calculated using the formula: pressure x volume = constant. This formula relates the pressure exerted on a gas and the volume of the gas in a container.

Q: What happens to gas pressure when the volume is increased?

When the volume of a gas is increased, the gas molecules have more space to move around, resulting in fewer collisions with the walls of the container. As a result, the pressure decreases.

Q: How does decreasing the volume of a gas affect its pressure?

When the volume of a gas is decreased, the gas molecules have less space to move around, leading to more frequent collisions with the walls of the container. This increases the pressure.

Summary & Key Takeaways

• Pressure in gases is generated by the constant collisions of gas molecules with each other and the walls of the container.

• The force exerted by these collisions can be calculated using the formula: pressure x volume = constant.

• Increasing the volume of a gas decreases its pressure, and vice versa.