Question

2 moles of $O_2\left(g\right)$, 3 moles of $H_2\left(g\right)$, and 1 mole of $He\left(g\right)$ are in a 600 ml container. Within container, total pressure is 760 torr. What is the partial pressure of $O_2$?

• A. 253 torr
• B. 127 torr
• C. 760 torr
• D. 380 torr
• E. 507 torr

Answer 1

The correct option is A 253 torr

Mole fraction of $O_2=\frac{2}{2+3+1}=0.333$
The partial pressure of $O_2$ is obtained by multiplying total pressure with mole fraction. It is $760\times 0.333=253torr$.