SOLUTION TO EXERCISE 15


Using either P = nkT or PV = NRT, you can use ratios to determine
the value for Mars as compared with Earth.  Pressure (P) on Mars is
0.007 that of Earth, and temperature (T) is 250/273 that of Earth, so the
number of gas molecules in 22.4 liters is

   6 * 10^23 * 0.007
  ------------------- = 4.6 * 10^21 
       250/273

Or, you can plug in R = 0.0821 (liters * atm) per (mole * K) to get

       PV       0.007 * 22.4 
  N = ----  =   ------------  = 0.0076 mole = 4.6 * 10^21 gas molecules.
       RT       0.0821 * 250