If the oxygen partial pressure in your mix is 1.3 ata at a depth of 37 msw (122 fsw), what is the fraction of oxygen in the mix?

To determine the fraction of oxygen in the mix when the oxygen partial pressure is 1.3 ata at a depth of 37 msw, we need to apply the concept of partial pressures and how they relate to the total pressure at that depth.

At any given depth, the total pressure can be calculated using the formula:

Total Pressure (ata) = Depth in meters + 1 (for the surface pressure, which is approximately 1 ata).

For a depth of 37 msw, the calculation would be:

Total Pressure = 37 msw + 1 ata = 38 ata

Now, in a gas mixture, the partial pressure of each gas can be found by multiplying the fraction of that gas in the mixture by the total pressure. Thus, knowing the partial pressure of oxygen (1.3 ata), we can set up the formula:

Partial Pressure of Oxygen (1.3 ata) = Fraction of Oxygen (X) × Total Pressure (38 ata).

To find the fraction of oxygen, we rearrange this equation to solve for X:

X = Partial Pressure of Oxygen / Total Pressure = 1.3 ata / 38 ata.

Calculating this gives:

X ≈ 0.03421.

This result