An analytical chemist weighs out 0.281g of an unknown diprotic acid into a 250mL volumetric flask and dilutes to the mark with distilled water. He then titrates this solution with 0.0700M NaOH solution. When the titration reaches the equivalence point, the chemist finds he has added 48.3mL of NaOH solution.
(a) Calculate the molar mass of the unknown acid. Round your answer to 3 significant digits.