Question

Calculate the partial pressure exerted by dioxygen from a mixture of 32gO$_2$, 80gAr (mol.mass 40) and 4 g dihydrogen (P$_{total}$=10bar).

• A. 1 bar
• B. 2 bar
• C. 4 bar
• D. 5 bar

Answer 1

Answer: (B)

2 bar

Answer 2

To calculate the partial pressure of dioxygen ($O_2$), we use Dalton's Law of Partial Pressures. Here's a step-by-step breakdown:

1. Calculate moles of each gas:

   • $O_2$: $\frac{32\,g}{32\,g/mol} = 1\,mol$
   • $Ar$: $\frac{80\,g}{40\,g/mol} = 2\,mol$
   • $H_2$: $\frac{4\,g}{2\,g/mol} = 2\,mol$

2. Total moles in the mixture:

   $$n_{total} = 1 + 2 + 2 = 5\,mol$$

3. Mole fraction of $O_2$:

   $$\chi_{O_2} = \frac{1}{5} = 0.2$$

4. Partial pressure of $O_2$:

   $$P_{O_2} = \chi_{O_2} \times P_{total} = 0.2 \times 10\,bar = 2\,bar$$

Therefore, the partial pressure exerted by dioxygen is 2 bar.