Question

Equal molar quantities of hydrogen gas and oxygen gas are present in a closed container at a constant temperature. Which of the following quantities will be the same for the two gases?

I. Partial pressure
II. Average kinetic energy
III. Average molecular velocity

• A. I
• B. I and II
• C. I and III
• D. II and III
• E. I, II and III

Answer 1

Answer: (B)

I and II

Equal molar quantities of hydrogen gas and oxygen gas are present in a closed container at a constant temperature. The I. Partial pressure and II. Average kinetic energy will be the same for the two gases.
Since number of moles are equal, the mole fractions are equal. Hence, the partial pressures will be equal as the partial pressures depends on mole fractions.
Average kinetic energy depends only on temperature. Hence, it will be same for two gases.
Following quantity will be different.
III. Average molecular velocity. It is inversely proportional to the square root of molar mass. Since molar masses of hydrogen and oxygen are different, they will have different average molecular velocities.