Noble gases (Group 18 in the periodic table) have the follow- ing volume concentrations in dry air: He, 5.24 ppm; Ne, 18.2 ppm; Ar, 0.934 vol%; Kr, 1.14 ppm; Xe, 87 ppb. (a) A concentration of 5.24 ppm He means 5.24 μL of He per liter of air. Using the ideal gas law in Problem 1-18, nd how many moles of He are contained in 5.24 μL of He at 25.008C (298.15 K) and 1.000 bar. This number is the molarity of He in the air. (b) Find the molar concentrations of Ar, Kr, and Xe in air at 25 C and 1 bar.

Definition Definition Any of various laws that describe the ways in which volume, temperature, pressure, and other conditions correlate when matter is in a gaseous state. At a constant temperature, the pressure of a particular amount of gas is inversely proportional with its volume (Boyle's Law) In a closed system with constant pressure, the volume of an ideal gas is in direct relation with its temperature (Charles's Law) At a constant volume, the pressure of a gas is in direct relation to its temperature (Gay-Lussac's Law) If the volume of all gases are equal and under the a similar temperature and pressure, then they contain an equal number of molecules (Avogadro's Law) The state of a particular amount of gas can be determined by its pressure, volume and temperature (Ideal Gas law)