Science Common Sense


1737 - What are the three laws of ideal gases and the ideal gas equation?

The three laws of ideal gases are:

  1. Boyle's Law: When you keep the temperature the same, the volume of a gas gets smaller if the pressure gets bigger, and vice versa. (Pressure and volume are inversely proportional)

For example, when you pump air into a football, the pressure increases, and the air gets squeezed into a smaller space.

  1. Charles' Law: When you keep the pressure the same, the volume of a gas gets bigger if the temperature gets higher, and vice versa. (Volume and temperature are directly proportional)

For example, when you heat a balloon, the air inside gets warmer and expands, making the balloon bigger.

  1. Gay-Lussac's Law (or Avogadro's Law in a different form and Amontons' Law): When you keep the volume the same, the pressure of a gas gets higher if the temperature gets higher, and vice versa. (Pressure and temperature are directly proportional)

For example, when you heat a gas in a container, the molecules move faster, hitting the container walls more, so the pressure increases.

These three laws can be combined into one equation called the Ideal Gas Equation: PV = nRT

Where: P is the pressure V is the volume n is the number of moles of the gas R is the gas constant T is the temperature in Kelvin