Charles’s law

Definition

Charles's Law states that the volume of an ideal gas is directly proportional to its absolute temperature at constant pressure. Mathematically, it is expressed as $V \propto T$ or $\frac{V_1}{T_1} = \frac{V_2}{T_2}$.

5 Must Know Facts For Your Next Test

1. Charles's Law applies only when the pressure of the gas remains constant.
2. The relationship between volume and temperature is linear in Charles's Law.
3. Absolute temperature must be used (Kelvin) for calculations involving Charles's Law.
4. The law can be derived from the ideal gas law by holding pressure and mole number constant ($PV=nRT$).
5. Graphically, a plot of volume versus temperature yields a straight line for an ideal gas under constant pressure.

Review Questions

• What condition must remain constant for Charles's Law to hold true?
• How does the volume of a gas change if its absolute temperature doubles, according to Charles's Law?
• Why must absolute temperature (Kelvin) be used when applying Charles's Law?

Related terms

Ideal Gas:

A theoretical gas composed of many randomly moving point particles that interact only through elastic collisions.

Boyle's Law:

States that the pressure of an ideal gas is inversely proportional to its volume at constant temperature.

Gay-Lussac’s Law: States that the pressure of an ideal gas is directly proportional to its absolute temperature at constant volume.