Question

Equal molar quantities of oxygen and hydrogen gas were placed in container A under high pressure. A small portion of the mixture was allowed to effuse for a very short time into the vacuum in container B. Which of the following is true concerning partial pressures of the gases at the end of the experiment?

• A. The partial pressure of hydrogen in container A is approximately four times as great as the partial pressure of oxygen in container A
• B. The partial pressure of oxygen in container A is approximately four times as great as the partial pressure of hydrogen in container A
• C. The partial pressure of hydrogen in container B is approximately four times as great as the partial pressure of oxygen in container B
• D. The partial pressure of oxygen in container B is approximately four times as great as the partial pressure of hydrogen in container B

Hint:

Use Graham’s law: rate $\propto 1/\sqrt{\(\text{molar mass}}$. Lighter gases escape faster.

Answer 1

The Correct Option is B

According to Graham’s Law, lighter gases (H$_2$) effuse faster than heavier ones (O$_2$). More hydrogen escapes, reducing its partial pressure more than oxygen. Hence, oxygen remains in higher proportion in A.