1.  convert activity of 1.1E+3 curies to atoms-decaying/sec

           ? atoms/sec = 1.1E+3 Ci *[(3.7E+10 atoms/Ci)] = 4.07 E+13

    convert amount of 1.00 g cobalt to atoms

           ? atoms = 1.00 g Co *[(6.02 E+23 atoms/60 g)] = 1.00 E+22

    activity = k * (amount present),     k = activity/amount

               k = (4.07 E+13 atoms-decaying/sec)/(1.00 E+22 atoms)
                 = 4.056 E-9 sec-1      

2.  A fraction has two parts, a numerator and demoninator, to represent
    two amounts of the same substance at different time points.  Use
    integrated form of first rate law... 
   
    k = ln(2)/(6.58 E+3 yrs) = 1.05 E-4 yrs-1

    ln (Ao/A) = k t = (1.05 E-4 yrs-1)*(100 yrs)
             = 1.05 E-2

    (Ao/A) = e1.05 E-2 = 1.0106

    The fraction remaining is current amount/starting amount = 1/1.0106

    fraction remaining = 0.9895 or 98.95 % is still there after 100 years


3.  Living things constantly replenish their C-14 content so as to have 
    a fixed activity of 15.3 counts/sec.  Once expired, the C-14 activity
    decreases with a half-life of 5720 years.  (Ao/A) = (1/0.795)

    k = ln(2)/5720 yrs = 1.21 E-4 yrs-1

    ln(1.258) = (1.21 E-4 yrs-1)*time

         time = 1900 years


4.  This example has a mass loss due to a nuclear reaction.  The products
    have less mass than reactants.  Convert mass loss to energy 
    using E = mc2.  

    Note units:  c (velocity of light) = 3.0 E+8 meters/sec

    force = mass * acceleration,      and energy  = force * distance

    force (in Newtons) = kg * meters/sec2

    energy (in Joules) = (kg * meters/sec2)*meters

        Joules = kg * (meters/sec)2

    mass loss of -0.0053 g/mol = 0.0053 E-3 kg/mol
         
    E (in Joules) = (0.0053 E-3 kg)*(9.0 E+16 (meters/sec)2)
                  = 4.77 E+11 Joules

5.  This example compares the mass of a Be-9 nucleus (containing  
    4 protons and 5 neutrons), with the mass of 4 individual protons and 
    5 individual neutrons.  The mass difference is the bindng energy that
    makes the 9 nucleons in the nucleus more stable than if they were
    independent particles.

    mass difference of -0.06248 g/mol = 0.06248 E-3 kg/mol

    E (in Joules) = (0.06248 E-3 kg/mol)*((9.0 E+16 (meters/sec)2))
                  = 5.62 E+12 Joules

    Binding Energy/nucleon = 5.62 E+12 Joules/9 = 6.25 E+8 kJ/mol/nucleon

    Convert to energy units of million electron volts (MeV) and compare
    with Figure 21.9 on page 1014.

    ? MeV = 6.25 E+8 kJ/mol/nu *[(1 MeV/1.60 E-16 kJ)*(1 mol/6.02 E+23)]
          = 6.5 Mev

    Find table 21.9 and note that Li-7 is at 5.8 MeV.  Be-9 is the next 
    element, so our value of 6.5 MeV is just about where it should appear 
    in the table.