Boyle's Law

Boyle's Law describes how a gas responds when temperature is held constant: if the space available for the gas gets smaller, the gas particles hit the container walls more often, so pressure increases. Because the amount of gas and temperature stay the same, pressure and volume change in opposite directions, giving a constant product of P and V. This relationship is a good model for many gas-compression situations as long as the gas behaves approximately ideally.

Use this formula for problems involving a fixed amount of gas that is compressed or expanded without changing temperature, such as syringes, pistons, scuba equipment, or sealed gas containers. It is especially useful when one pressure or volume is unknown and the other conditions are unchanged.

• using temperatures in the calculation when temperature is supposed to stay constant
• forgetting that volume and pressure must be in matching units on both sides of the equation
• rearranging the formula incorrectly and dividing by the wrong volume or pressure