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)?
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
To determine the pressure of the CO2(g) in this scenario, we need to consider the effect of water vapor on the total pressure measured.
First, let's understand the concept of vapor pressure. Vapor pressure is the pressure exerted by the gaseous phase of a substance when it is in equilibrium with its liquid or solid phase at a particular temperature. In this case, the water vapor above the water surface exerts its own pressure, which needs to be taken into account.
To find the pressure of the CO2 gas, we need to subtract the vapor pressure of the water at 20 degrees Celsius from the total atmospheric pressure.
1. Find the vapor pressure of water at 20 degrees Celsius:
You can find table values or use online resources to find the vapor pressure of water at different temperatures. At 20 degrees Celsius, the vapor pressure of water is approximately 17.5 mmHg.
2. Subtract the vapor pressure of water from the atmospheric pressure:
Atmospheric pressure - Vapor pressure of water
715.8 mmHg - 17.5 mmHg = 698.3 mmHg
Therefore, the pressure of the CO2(g) in the bottle is approximately 698.3 mmHg.