Question

Oxygen and cyclopropane at partial pressures of 570 $torr$ and 170 $torr$ respectively are mixed in a gas cylinder. What is the ratio of the number of moles of cyclopropane to the number of moles of oxygen?

• A. $\frac{170}{740}=0.23$
• B. $\frac{170}{42}/\left[\frac{170}{42}+\frac{570}{32}\right]=0.19$
• C. $\frac{170\times 42}{570\times 32}=0.39$
• D. $\frac{170}{570}=0.30$

Answer 1

The correct option is D $\frac{170}{570}=0.30$

At constant volume and temperature :

$\frac{P_{cyclopropane}}{P_{oxygen}}=\frac{n_{cyclopropane}}{n_{oxygen}}$

$\frac{n_{cyclopropane}}{n_{oxygen}}=\frac{170}{570}=0.30$