One common science homework question is to list 3 ways to increase the pressure of a gas container or a balloon. This is an excellent question because answering it helps you understand what pressure is and how gases behave.

### What Is Pressure?

Pressure is the amount of force exerted over a unit of area.

P = F/A

pressure = force divided by area

As you can see from looking at the equation, two ways to increase pressure are to (1) increase the amount of force or (2) decrease the area over which it is exerted. How exactly do you do that? That's where the Ideal Gas Law comes into play.

### Pressure and the Ideal Gas Law

At low (ordinary) pressures, real gases behave like ideal gases, so you can use the Ideal Gas Law to determine how to increase the pressure of a system. The Ideal Gas Law states:

PV = nRT

where P is pressure, V is volume, n is the number of moles of a gas, R is Boltzmann's constant, and T is temperature

If we solve for P:

P = (nRT)/V

### Three Ways to Increase the Pressure of a Gas

- Increase the amount of gas. This is represented by the "n" in the equation. Adding more molecules of a gas increases the number of collisions between the molecules and the walls of the container. This raises pressure.
- Increase the temperature of the gas. This is represented by "T" in the equation. Increasing temperature adds energy to the gas molecules, increasing their motion and, again, increasing collisions.
- Decrease the volume of the gas. This is the "V" in the equation. By their very nature, gases can be compressed, so if the same gas can be put into a smaller container, it will exert a higher pressure. The gas molecules will be forced closer to each other, increasing collisions (force) and pressure.