You measure 2.34 g of K2Cr2O7 into a volumetric flask. You dilute the K2Cr2O7 with water to a volume of 250 mL. It takes 35.7 mL of this solution to titrate 17.8 mL of a solution of Na2C2O4 in the presence of excess acid. What was the concentration of the original Na2C2O4 solution?