Ive already checked it DrBob222 that's the problem the teacher gave. Here's the complete problem : Exhaled breathe is a mixture of Nitrogen, oxygen, carbon dioxide and water vapor. What is the partial pressure of CO2(torr) in exhaled breathe at 37.0 degree C if the partial pressure of Oxygen is 116 torrr and that of nitrogen is 659 torr. Assume the atmospheric pressure is 1.00 atm.
I may be missing something but
Ptotal = pCO2 + pN2 + pO2 + pH2O and I don't see anything in the problem to suggest that pO2 and pN2 should be changed to other conditions (temperature etc). BUT, and this is my problem, 659 + 116 = 775 torr which is more than the total of 760. That will make pCO2 negative and that can't be true. Perhaps another tutor can spot the problem.
thanks a lot
DrBob is correct, something is wrong with the data. I suspect it is the value of pN2 should have been typed 569, which is quite close to what is found in Earth's atmosphere.
http://diatronic.co.uk/nds/webpub/partial_pressures.htm
To find the partial pressure of carbon dioxide (CO2) in exhaled breath, we need to use Dalton's law of partial pressures. According to Dalton's law, the total pressure of a mixture of gases is equal to the sum of the partial pressures of each individual gas.
In this case, we know the partial pressures of oxygen (O2) and nitrogen (N2), and we need to find the partial pressure of carbon dioxide.
To determine the partial pressure of CO2, we need to subtract the partial pressures of O2 and N2 from the total atmospheric pressure. However, we need to remember that all the pressures must be in the same unit. In this case, the atmospheric pressure is given as 1.00 atm, so we need to convert the partial pressures of O2 and N2 to atmospheres as well.
To convert torr to atmospheres, we can use the conversion factor: 1 atm = 760 torr.
Converting the given partial pressures of O2 and N2 to atmospheres:
Partial pressure of O2 = 116 torr * (1 atm / 760 torr) = 0.153 atm
Partial pressure of N2 = 659 torr * (1 atm / 760 torr) = 0.866 atm
Now, we can calculate the partial pressure of CO2 using Dalton's law:
Partial pressure of CO2 = Total pressure - Partial pressure of O2 - Partial pressure of N2
Since the total pressure is given as 1.00 atm, substituting the values:
Partial pressure of CO2 = 1.00 atm - 0.153 atm - 0.866 atm
Partial pressure of CO2 = 0.153 atm
Therefore, the partial pressure of carbon dioxide (CO2) in exhaled breath at 37.0 °C is 0.153 atm, which corresponds to approximately 116.4 torr.