Furoic acid, HC5H3O3, has a Ka value of 6.76 10-4 at 25°C. Calculate the pH at 25°C for each of the following.
(a) a solution formed by adding 33.0 g of furoic acid and 28.0 g of sodium furoate, NaC5H3O3, to enough water to form 0.210 L of solution
(b) a solution formed by mixing 30.0 mL of 0.171 M HC5H3O3 and 15.0 mL of 0.26 M NaC5H3O3 and diluting the total volume to 135 mL
(c) a solution prepared by adding 51.0 mL of 1.63 M NaOH solution to 0.520 L of 0.0912 M HC5H3O3