Charles' Law Calculation

Charles' Law is a specific instance of the Ideal Gas Law in which volume and temperature are linearly proportional at constant pressure and mass. Here's how to solve a direct proportion problem using Charles' Law.

Remember volume V and temperature T are directly proportional to each other at constant pressure P and mass n. If you know that T changes by a factor z, then you can calculate V_final = z x V_initial

For example, if the temperature of a 3.5 L sample of helium gas is increased from 300 K to 900 K, what is its new volume?

The temperature has increased by a factor of 3 (900/300) so:

V_final = z x V_initial
V_final = 3 x 3.5 L
V_final = 10.5 L

Calculation Tip

Be sure the temperature is expressed in Kelvin. If you are given a temperature in degrees Celsius or Fahrenheit, convert it to Kelvin before determining the factor z.