Ideal gas law

Definition

The Ideal Gas Law is a fundamental equation in chemistry that relates the pressure, volume, temperature, and amount of an ideal gas. It is represented by the formula $PV = nRT$ where $P$ is pressure, $V$ is volume, $n$ is the number of moles, $R$ is the gas constant, and $T$ is temperature.

5 Must Know Facts For Your Next Test

1. The Ideal Gas Law combines Boyle's Law, Charles's Law, and Avogadro's Law into a single equation.
2. The value of the gas constant $R$ depends on the units used for pressure, volume, and temperature; a common value is 0.0821 L·atm/mol·K.
3. Ideal gases are hypothetical gases that perfectly follow the Ideal Gas Law under all conditions; real gases approximate this behavior at high temperatures and low pressures.
4. Temperature must always be converted to Kelvin when using the Ideal Gas Law.
5. The Ideal Gas Law can be used to derive other important relationships such as calculating molar mass or density of a gas.

Review Questions

• What variables are related by the Ideal Gas Law?
• In what unit must temperature be measured when using the Ideal Gas Law?
• How does the value of the gas constant $R$ change with different units?

Related terms

Boyle's Law: $P_1V_1 = P_2V_2$, stating that at constant temperature for a fixed amount of gas, pressure and volume are inversely proportional.

Charles's Law: $V_1/T_1 = V_2/T_2$, stating that at constant pressure for a fixed amount of gas, volume and temperature are directly proportional.

Avogadro's Law: $V/n = k$, stating that at constant temperature and pressure, volume and number of moles are directly proportional.