Avogadro's Law Calculation

Chemistry Quick Review of Avogadro's Law Calculation

Avogadro's Law is a specific case of the Ideal Gas Law.
Avogadro's Law is a specific case of the Ideal Gas Law. Tetra Images, Getty Images

Avogadro's Law is a specific instance of the Ideal Gas Law in which the volume of a gas is directly proportional to the number of moles at constant temperature and pressure. Here's how to solve a direct proportionality problem using Avogadro's Law.

V ∝ n with constant temperature and pressure

If the number of moles of a gas changes by a factor of z, then you can calculate:

Vfinal = z x Vinitial

Example: A 2.0 mole sample of a gas is known to occuy 30.0 L of volume.

Calculate the V for 1.0 mole of the gas.

n changes by a factor of 1/2, so:

Vfinal = z x Vinitial

 

Vfinal = 1/2 x 30.0 L

Vfinal = 15.0 L