Using A sample having X amount of oxalic acid. If 0.5187 grams of the sample requires 40.20 mL of 0.1000 M Sodium hydroxide to neutralize the oxalic acid completely, what is the percentage of oxalic acid in the sample? The molar mass of oxalic acid is 90.035 g/mol. The balanced equation for the reaction is: H2C2O4 + 2 NaOH ® 2 H2O + Na2C2O4