2) The pH of unbuffered water, such as rain, is decreasing consistently over time as atmospheric CO2 concentrations increase.

a) What will be the atmospheric CO2 level (in ppm) when the pH of rain water reaches 5.55 at 25 C?

b) What would be the pH of buffered water (over CaCO3 limestone at 25 C) at the CO2 level in part a)?

c) Determine the concentrations of HCO3 and CO32 ions in the buffered water of part b) and then determine the alkalinity of the solution in ppm CaCO3.