# A mixture of .250 moles O2, .297 moles N2, and .134 moles Ar has a total pressure of 1.95 atm. What is the mole fraction of O2 and what is the partial pressure of O2?

Jul 20, 2017

Mole fraction = $0.367$
Partial pressure = $\text{0.716 atm}$

#### Explanation:

"Mole fraction of a gas"=("Number of moles of gas")/("Total moles of gas")

For ${O}_{2}$:

$\text{Mole fraction of}$ ${O}_{2}$

$= \frac{0.250}{0.250 + 0.134 + 0.297} = \frac{0.250}{0.681} \approx 0.367$

$\text{Partial pressure of a gas" = "Mole fraction" xx "Total pressure}$

For ${O}_{2}$:

$\text{Partial pressure of}$ ${O}_{2}$

$= 0.367 \times \text{1.95 atm} \approx 0.716$ $\text{atm}$