Question

A sample of CO₂ is collected over water at 23^oC. If the total pressure of the sample is 734 torr, and the vapor pressure of water at 23^oC is 21.2 torr, what is the partial pressure of CO₂ in torr? DON"T WRITE THE UNITS: ONLY THE VALUES.

Answer 1

Since the sample of CO₂ is being collected over water, the total pressure of the sample will be equal to the pressure because of CO₂ (i.e. partial pressure of CO₂) and the vapor pressure of water. Note that this assumes there is no other gas present with significant contribution to the total pressure.

Hence, we can write

Given that

We can calculate the partial pressure of CO₂ in torr as follows:

Hence, the answer will be 712.8.

Note: if needed round up the answer to three significant figures and enter the answer as 713.