Question

A gas cylinder contains $55$% nitrogen, $20$% oxygen and $25$% carbon dioxide by mass, at $760mm$ pressure. Calculate the partial pressure of each gas.

Answer 1

According to Dalton's law of partial pressure:

Moles of Nitrogen = $\frac{55}{28}=1.964$

Moles of Oxygen = $\frac{20}{32}=0.625$

Moles of $C{O}_2$=$\frac{25}{44}=0.568$

Total moles = 3.157

$P^{\prime }=\text{mole fraction}\times P_M$

$P_{N_2}=\frac{1.964}{3.157}\times 760=472.8mm$

$P_{O_2}=\frac{0.625}{3.157}\times 760=150.4mm$

$P_{N_2}=\frac{0.568}{3.157}\times 760=136.7mm$