Question

The pressure of a $1:4$ mixture by moles of dihydrogen and dioxygen enclosed in a vessel is $1$ bar. Calculate the partial pressure of dioxygen.

• A. $0.8\times {10}^4\text{bar}$
• B. $0.008{\text{N m}}^{-2}$
• C. $8\times {10}^4{\text{N m}}^{-2}$
• D. $0.08\text{bar}$

Answer 1

The correct option is C $8\times {10}^4{\text{N m}}^{-2}$

Let the number of moles of dihydrogen and dioxygen be 1 and 4.
$\therefore$ Mole fraction of $O_2=\frac{4}{1+4}=\frac{4}{5}$
So, Partial pressure of dioxygen = Mole fraction $\times$ Total pressure
= $\frac{4}{5}\times 1=0.8\text{bar}$
Now, $1\text{bar}$ = ${10}^5{\text{N m}}^{-2}$
So, $0.8\text{bar}$ = $0.8\times {10}^5{\text{N m}}^{-2}$
Thus, the partial pressure of dioxygen would be $8\times {10}^4{\text{N m}}^{-2}$.