A compound used as a preservative is made up only of C, H, O, and Na. At STP, a sample of the compound weighing 100 mg was burned with excess oxygen. After the reaction is complete, 108.88 mL of CO₂ and 38.88 mL of H₂O were produced. In a separate analysis, it was found that the sample contains 15.96 mg of Na. Determine the molecular formula of the preservative.