Question

A flask contains an equal mixture of oxygen and argon. Which of the following statements is true about the effusion of the gases?

Argon will effuse 1.07 times faster than oxygen.

Oxygen will effuse 1.19 times faster than argon.

Oxygen will effuse 5.29 times slower than argon.

Argon will effuse 1.48 times slower than oxygen.

Answer 1

Given that the pressure, temperature and area of effusion is constant, the rate of effusion is inversely proportional to the square root of the molecular mass of the gas.
Mr Oxygen = 32
Mr Argon = 40
Effusion Oxygen = 1/√32
Effusion Argon = 1/√40
Effusion Oxygen / Effusion Argon = √(40) / √(32)
=√(40/32) = √(5/4) = 1.19
Thus, Oxygen will effuse 1.19 times faster than Argon. The second option is correct.