Question

Two gases A and B having molecular weights $60$ and $40$ respectively are enclosed in a vessel. The weight of A is $0.45\text{g}$ and that of B is $0.1\text{g}$. The total pressure of the mixture is $900\text{mm of Hg}$. Calculate the partial pressure of the gas A.

• A. $500\text{mm of Hg}$
• B. $450\text{mm of Hg}$
• C. $675\text{mm of Hg}$
• D. $225\text{mm of Hg}$

Answer 1

The correct option is C $675\text{mm of Hg}$

Moles of A $=\frac{0.45}{60}=0.0075$
Moles of B $=\frac{0.1}{40}=0.0025$
Total moles $=0.01$
Total pressure $=900\text{mm of Hg}$
$\therefore$ Partial pressure of A $=\frac{0.0075}{0.01}\times 900=675\text{mm of Hg}$