The Gas Pressure Lab

The Gas Pressure Lab 💨

A gas seems to be nothing at all — but it pushes. It inflates a balloon, drives a piston, and can burst a sealed can. That push is **pressure**. To understand it, we have to zoom in to the particles.

Billions of tiny hits 🧱

The particles in a gas move **fast and at random** in all directions. Constantly, they **collide with the walls** of their container. Each collision pushes on the wall with a tiny force. Add up billions of these collisions every second across the whole wall, and you get **gas pressure** — the force per unit area on the walls.

What makes the pressure?

What causes the pressure a gas exerts on its container?

• Gas particles colliding with the container walls
• Gas particles colliding with each other in the middle
• The weight of the gas pressing down under gravity
• Particles sticking to the walls and staying there

Temperature and speed 🌡️

**Temperature** is a measure of the **average kinetic energy** of the particles in a gas. The hotter the gas, the **faster** its particles move on average, and the more kinetic energy they carry. Cool it down and the particles slow.

Match each term to its meaning

Heat it up (same volume) 🔥

Seal a gas in a rigid container so its **volume cannot change**, then heat it. The particles speed up, so they hit the walls **harder** and **more often**. The result: at **constant volume**, raising the **temperature** raises the **pressure**.

Heating a sealed can

An interactive activity.

What raises the pressure?

Select ALL THREE changes that increase the pressure of a fixed amount of gas.

• Raising the temperature while keeping the volume constant
• Making the particles hit the walls harder and more often
• Squeezing the same gas into a smaller volume
• Cooling the gas down
• Letting the gas expand into a bigger volume
• Removing some of the gas particles

Work on a gas 🚲

You can raise a gas's energy without heating it — by **doing work on it**. When you **compress** a gas quickly, you transfer energy to it, increasing its **internal energy** and raising its **temperature**. That is why a **bike pump gets warm** as you push the air into the tyre.

Why the warm pump?

The barrel of a bike pump gets noticeably warm as you pump air into a tyre. What is the best explanation?

• Compressing the air does work on the gas, raising its internal energy and temperature
• The gas cools down as it is squeezed into a smaller space
• Wind blowing past the pump heats the metal
• The air particles stop moving when compressed

Lab summary

Gas pressure is caused by particles _____ with the container walls. Temperature measures the average _____ energy of the particles, so heating a gas at constant volume makes them hit the walls harder and raises the _____. Doing _____ on a gas by compressing it increases its internal energy.