Answer to Question #161195 in Chemistry for J

Question

1.0 mole samples of nitrogen gas and argon gas are placed into separate 5.0 L containers.  If each container has a pinhole opening which gas will be slower to effuse from its container? (Explain)

Answer 1

The rate of effusion is inversely proportional to the square root of the molar mass of the gas:

$r \propto \frac{1}{\sqrt{M}}$ .

The molar masses of nitrogen N₂ and argon Ar gases are 28.01 g/mol and 39.95 g/mol, respectively. As one can see, the molar mass of Ar is higher than that of N₂. Therefore, the effusion rate of Ar will be smaller than that of N₂. It means that Ar will be slower to effuse from its container.