Question

An enclosure of volume 3 litre contains 16 gm of oxygen, 7 gm of nitrogen and 11 gm of carbon-di-oxide at ${27}^{\circ }$C. Find the pressure exerted by the mixture

• A. 88.2 atm
• B. 8.2 atm
• C. 18.2 atm
• D. 7.2 atm

Answer 1

The correct option is B 8.2 atm

22.4 litre of 1 mol at normal temperature has pressure of 1 atmosphere
PV = nRT $\therefore P=\frac{nRT}{V}$
or 1 atmosphere = $\frac{1\times R\times 273}{22.4}$
For $O_2$ 16 gm, is $\frac{1}{2}$ mole
Pressure of $O_2=\frac{\frac{\frac{1}{2}\times R\times 300}{3}}{\frac{1\times R\times 273}{22.4}}atm=4.1atm$
For $N_2$, 7 gm is $\frac{1}{4}$ mole
Pressure of $N_2=\frac{(\frac{1}{4}\times \frac{R\times 300}{3})}{\left(\frac{1\times R\times 273}{22.4}\right)}=2.05atm.$
For $C{O}_2$, 11 gm is $\frac{1}{4}$ mole
$\therefore \text{Pressure of}C{O}_{2}is=\frac{\frac{1}{4}\times \frac{R\times 300}{3}}{\frac{1\times R\times 273}{22.4}}$
= 2.05
Total Pressure= 4.1 + 2.05 + 2.05 = 8.2 atm.