A heliox deep-sea diving mixture contains 2.0 g of oxygen to every 98.0 g of helium.

What is the partial pressure of oxygen when this mixture is delivered at a total pressure of 8.6 atm ?

We’re being asked to **calculate the partial pressure of oxygen (O)** in a **mixture of oxygen (O) and helium (He)**.

Recall that the ** partial pressure of a gas (P_{Gas})** in a mixture is given by:

$\overline{){{\mathbf{P}}}_{{\mathbf{gas}}}{\mathbf{}}{\mathbf{=}}{\mathbf{}}{{\mathbf{\chi}}}_{{\mathbf{gas}}}{{\mathbf{P}}}_{{\mathbf{total}}}}$

where **χ**** _{Gas}** = mole fraction of the gas and

The ** mole fraction of the gas** is then given by:

$\overline{){{\mathbf{\chi}}}_{{\mathbf{gas}}}{\mathbf{}}{\mathbf{=}}{\mathbf{}}\frac{\mathbf{moles}\mathbf{}\mathbf{gas}}{\mathbf{total}\mathbf{}\mathbf{moles}}}$

We will do the following steps to solve the problem:

Step 1: Calculate the moles of O and He

Step 2: Calculate the mole fraction of O

Step 3: Calculate the partial pressure of O

Partial Pressure