At 273 K and 1 atm pressure, 1.0 mol of N_{2} occupies 22.4 L.
Calculate the number of N_{2} molecules in 1.0 L. At 277 K,
1.0 L of water weighs 1.0 kg. Calculate the number of moles of water
in 1.0 L. Calculate the number of H_{2}O molecules in 1.0 L
at 277 K. The density of lead (Z, 82; at. wt. 207.2) is 11.29 g/mL,
calculate the number of lead atoms in 1.0 L. (1.0 mole of N_{2}
has 6.02x10^{23} N_{2} molecules).
The purpose is to compare the particle density of solid, liquid, and gaseous
states of some material so that you can picture or estimate the number
of collisions an ionizing particle has over its path.