A sample of oxygen gas is collected by displacement of water at 25°C and 1.17 atm total pressure. If the vapor pressure of water is 23.756 mm Hg at 25°C, what is the partial pressure of the oxygen gas in the sample?

Ptotal = pO2 + pH2O

You know Ptotal and pH2O, solve for pO2. Note Ptotal and pH2O are not in the same units.

To find the partial pressure of the oxygen gas in the sample, we need to subtract the vapor pressure of water from the total pressure.

Given:
Total pressure (Ptotal) = 1.17 atm
Vapor pressure of water (Pwater) = 23.756mm Hg

However, we need to convert the units of vapor pressure from mm Hg to atm so that the units are consistent.

1 atm = 760 mm Hg

Therefore, Pwater = 23.756 mm Hg * (1 atm / 760 mm Hg) ≈ 0.0313 atm

Now, we can subtract the vapor pressure of water from the total pressure to find the partial pressure of the oxygen gas:

Partial pressure of oxygen gas (Poxygen) = Ptotal - Pwater
= 1.17 atm - 0.0313 atm
= 1.1387 atm

So, the partial pressure of the oxygen gas in the sample is approximately 1.1387 atm.