Calculate the pH of CO2-saturated water at 25 degrees C, given that the CO2 concentration in air is 366 and that for carbon dioxide the Henry's Law constant KH=3.4E-2 mol L-1 atm-1 at 25 degrees C. Furthermore, the ionization constant, Ka, for H2CO3 has a value of 4.5E-7 mol L-1 at this temperature.