3.) Co2(g) is collected over water at 20 degrees Celsius. The pressure in the bottle is equalized with the atmospheric pressure, which is measured to be 715.8mmHg. What is the pressure of the Co2(g)?

Answer 1

Look up the vapor pressure of H2O at 20 C. That is pH2O.

Ptotal = PCO2 + PH2O

You know Ptotal = 715.8
You know pH2O is what you looked up.
Solve for pCO2