Write the equation for the dissociation of butyric acid, HC4H7O2 in water. a. Write the Ka expression for this dissociation. b. Calculate the Ka of butyric acid if the pH of a 0.50-M solution is 2.56. 2. Calculate the pH of a buffer solution in which the [HC4H7O2] = 0.36M and [C4H7O2-] = 0.31M.