Saccharin is a weak organic base with a Kb of 4.8X10^-3. A 0.672-g sample of saccharin dissolved in 30.0mL of water had a pH of 12.34. What is the molar mass of saccharin?

Consider the reaction CO3^-2+H2O<==>HCO3^+OH^-. Kb for CO3^-2 is 2.1x10^-4 at 25 Celsius . What is Ka for the HCO3^- ion at 25 Celsius?