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The Basic Gas Laws Explained

Tap a law to see what it states.

Boyle's Law

States that at a constant temperature, the pressure of a gas is inversely proportional to its volume β€” as volume decreases, pressure increases, and vice versa.

Charles's Law

States that at constant pressure, the volume of a gas is directly proportional to its absolute temperature β€” as temperature increases, volume increases proportionally.

Gay-Lussac's Law

States that at a constant volume, the pressure of a gas is directly proportional to its absolute temperature β€” as temperature increases, pressure increases proportionally.

The Ideal Gas Law

Combines the relationships between pressure, volume, temperature, and the amount of gas into a single equation (PV = nRT), providing a unified way to predict how a gas will behave under different conditions.

Real-World Applications

These laws explain everyday phenomena such as why a sealed bag of chips expands at high altitude (lower external pressure), why tire pressure changes with temperature, and how weather balloons expand as they rise.

Why these laws only perfectly describe an "ideal" gas

These laws technically describe the behavior of an idealized gas β€” one where gas particles have no volume and no intermolecular attraction β€” and while real gases only approximate this ideal behavior, the gas laws remain remarkably accurate predictors under most everyday temperature and pressure conditions.

Frequently Asked Questions

Why does a balloon shrink when placed in a freezer?

This directly demonstrates Charles's law β€” as the temperature of the gas inside the balloon decreases, its volume decreases proportionally as well, assuming the pressure stays roughly constant.

Do the gas laws still apply at extremely high pressures or very low temperatures?

Not perfectly β€” under extreme conditions, real gases begin to deviate meaningfully from ideal gas behavior, since factors like molecular volume and intermolecular forces (which the ideal gas law ignores) become more significant.