When air is inhaled, it enters the alveoli of the lungs, and varying amounts of the component gases exchange with dissolved gases in the blood. The resulting alveolar gas mixture is quite different from the atmospheric mixture. The following table presents Gas N₂ 0₂ CO₂ H₂O Atmosphere (sea level) Alveoli Partial Partial Mole % Pressure (torr) Mole % Pressure (torr) 78.6 20.9 00.04 00.46 569 104 40 47 selected data on the composition and partial pressure of four gases in the atmosphere and in the alveoli: If the total pressure of each gas mixture (atmosphere, alveoli) is 1.00 atm(=760torr), calculate: (a) The partial pressure (in torr) of each gas in the atmosphere (b) The mole % of each gas in the alveoli (c) The number of O2 molecules in 0.50 L of alveolar air (volume of an average breath of a person at rest) at 37°C
Ideal and Real Gases
Ideal gases obey conditions of the general gas laws under all states of pressure and temperature. Ideal gases are also named perfect gases. The attributes of ideal gases are as follows,
Gas Laws
Gas laws describe the ways in which volume, temperature, pressure, and other conditions correlate when matter is in a gaseous state. The very first observations about the physical properties of gases was made by Robert Boyle in 1662. Later discoveries were made by Charles, Gay-Lussac, Avogadro, and others. Eventually, these observations were combined to produce the ideal gas law.
Gaseous State
It is well known that matter exists in different forms in our surroundings. There are five known states of matter, such as solids, gases, liquids, plasma and Bose-Einstein condensate. The last two are known newly in the recent days. Thus, the detailed forms of matter studied are solids, gases and liquids. The best example of a substance that is present in different states is water. It is solid ice, gaseous vapor or steam and liquid water depending on the temperature and pressure conditions. This is due to the difference in the intermolecular forces and distances. The occurrence of three different phases is due to the difference in the two major forces, the force which tends to tightly hold molecules i.e., forces of attraction and the disruptive forces obtained from the thermal energy of molecules.
#(a):
The total atmospheric pressure at sea level is, Pt = 1 atm or 760 torr
Partial pressure of a gas is calculated using the below formula:
Partial pressure = Mole fraction * Total pressure(Pt)
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