Combined Gas Law

The combined gas law is a gas law that combines Charles's law, Boyle's law, and Gay-Lussac's law. It is used to relate the pressure, volume, and temperature of a gas sample under changing conditions. The combined gas law is expressed as:

P1V1 / T1 = P2V2 / T2

Explanation of Variables:

• P1: initial pressure of the gas
• V1: initial volume of the gas
• T1: initial temperature of the gas (in Kelvin)
• P2: final pressure of the gas
• V2: final volume of the gas
• T2: final temperature of the gas (in Kelvin)

Using the Combined Gas Law

To use the combined gas law, follow these steps:

1. Identify the initial and final conditions of the gas (pressure, volume, and temperature).
2. Convert temperatures to Kelvin if they are given in Celsius (add 273 to Celsius temperature).
3. Substitute the values into the formula: P1V1 / T1 = P2V2 / T2
4. Solve for the unknown variable using algebraic manipulation.

Example Problem:

Suppose a gas has an initial pressure of 3 atm, an initial volume of 2 L, and an initial temperature of 300 K. If the gas is compressed to a final volume of 1 L at a temperature of 350 K, what is the final pressure of the gas?

Using the combined gas law formula: P1V1 / T1 = P2V2 / T2

Substitute the given values: (3 atm)(2 L) / (300 K) = P2(1 L) / (350 K)

Solving for the final pressure, P2 = (3 atm)(2 L)(350 K) / (1 L)(300 K) = 7 atm

Therefore, the final pressure of the gas is 7 atm.

Remember to always use the appropriate units for pressure, volume, and temperature when using the combined gas law.

Practice using the combined gas law with various examples to solidify your understanding of the concept.

Happy studying!