Calculate the pressure of CO2 in the system, mmHg

Question

Givens are:

atmospheric pressure, mmHg = 756.92 mmHg

temperature of H2O = 21.0 degrees Celsius

Vapor pressure of H2O at this temperature = 18.7 mmHg

Answer 1

You didn't describe the experiment, but it seems as though the gas (CO₂) was collected over water, and you are asked to find the pressure of CO₂. When a gas is collected over water, the vapor pressure of the water must be deducted from the total pressure to obtain the pressure of the collected gas.

756.92 mm Hg - 18.7 mm Hg = 738.2 mm Hg = pressure of CO₂