can treat the air inside the lungs as an ideal gas. To find the number of molecules, we can use the ideal gas law. PV = NkT Here volume is given in the Litre. Litre is volume occupied by a cube of side cm.
1Litre = 10cm × 10cm × 10cm = – m N PV kT Pa JK K Molecules Only % of N are oxygen. The total number of oxygen molecules = . × × Number of oxygen molecules = . × molecules EXAMPLE .
Calculate the volume of one mole of any gas at STP and at room temperature (300K) with the same pressure atm. Solution We can take air molecules in the tire as an ideal gas. The number of molecules and the volume of tire remain constant. So the air molecules at °C satisfies the ideal gas equation P V = NkT and at °C it satisfies P V = NkT But we know V = V = V PV PV NkT NkT T P K K Pa kPa EXAMPLE .
When a person breaths, his lungs can hold up to . Litre of air at body temperature °C and atmospheric pressure ( atm = kPa). This Air contains % oxygen. Calculate the number of oxygen molecules in the lungs.
- - - - Unit Heat and thermodynamics determine the number of mole. At room temperature 300K, the volume of a gas occupied by any gas is equal to .6L. The number of mole μ= . × ≈ mol.
Air is the mixture of about % oxygen, % nitrogen and remaining one percent are argon, hydrogen, helium, and xenon. The molar mass of air is gmol – . So the total mass of air in the room m = × ×