Two liters of oxygen (O2) is collected over water at 20oC. If the total pressure in the container is 95.00 kPa, what is the partial pressure of the oxygen gas?

A) 92.00 kPa

B) 92.67 kPa

C) 95.00 kPa

D) 97.33 kPa

Temperature (oC) Vapor pressure (kPa)

0 0.61

20 2.33

60 19.92

100 101.3

THE PARTIAL PRESSURE OF OXYGEN GAS IN THE CONTAINER IS 92.67kPa WHICH IS OPTION B.

Explanation:

To calculate the partial pressure of oxygen gas collected over water, we use

Ptotal = Poxygen + P water

It is worthy to note that when oxygen is collected over water, it is mixed with water vapor and the total pressure in the container will be the sum of the pressure exerted by the oxygen gas and that of the water vapor at that given temperature.

At 20 C, the vapor pressure of water as given in the question is 2.33 kPa.

Using the above formula,

Ptotal = Poxygen + P water

Substituting for Poxygen, we have;

Poxygen = Ptotal - P water vapor

P oxygen = 95 .00 kPa - 2.33 kPa

P oxygen = 92.67 kPa.

The partial pressure of oxygen gas in the container is hence, 92.67kPa.