The average pH of precipitation in rural areas is 5.70. Assuming that the pH
is controlled by the carbonate system, i.e., no anthropogenic acid gases are present 
in the atmosphere, calculate the amount of calcium carbonate (mg) dissolved per liter 
of rainwater. pKa1=6.33, KCO2=3.388e-02





Hint: pCO2=3.162e-04