SANDA CORPORATION APPLICATION NOTES QC BORIC ACID 1A Rapid, quantitative determination of boric acid is possible with the SANDA Thermo Titrator. The acid was titrated with sodium hydroxide, yielding very good stoichiometric results. Experiment A 0.1N solution of boric acid was prepared by dissolving 1 gm of the solid (obtained from Fisher Scientific) in up to 500 mL distilled water. The titrant, 0.5N NaOH, was prepared by diluting 25 mL of a 5N (Baker Dilut-It) solution to 250 mL volumetrically. 25 gm of mannitol (Atlas) were dissolved in up to 500 mL of distilled water to prepare a 0.5M solution. Procedure Varying amounts of the acid solution were titrated with NaOH. Another series of titrations was done to investigate the effect on the heat of reaction of mannitol. To each sample, 5.0 mL of the prepared sugar solution was added before titration. The heat of reaction was found to have increased only slightly and the results obtained were not as accurate as those from the previous series of titrations (without the addition of mannitol). The minimum detection limit of boric acid with the SANDA Thermo-Titrator has been found to be 0.002% with a standard deviation of 0.01. Minute quantities of boric acid may be titrated with the SANDA TRACE ANALYZER. Reference: J. Jordon, J. Chem. Educ. 40, A5 (1963) Borax determination on reverse SODIUM TETRABORATE by Thermometric Titration Borax, a sample of unknown source, was determined with the SANDA THERMO TITRATOR using 1N sulfuric acid as the titrant. Excellent stoichiometric results were obtained by this rapid titration method. The titration with sulfuric acid resulted in sharper endpoints than that in the titration with HCl. 1N sulfuric acid is preferred. REAGENT 1N H2SO4 Fisher Standard solution 0.1 Na2B4O7 9.532 g borax were dissolved in 250 mL distilled water Aliquots of 5, 10, 15 and 20 mL were titrated with 1N H2SO4. INSTRUMENT PARAMETERS Sensitivity: 7 Cut-off Adj: 7.7 Buret Injection Speed: 0.0667 mL/second. RESULTS 5 mL Borax Solution = 1.28 mL 1N H2SO4 10 mL Borax Solution = 2.41 mL 1N H2SO4 15 mL Borax Solution = 3.56 mL 1N H2SO4 20 mL Borax Solution = 4.68 mL 1N H2SO4 Y-intercept: 0.145 Cor. Coefficient: 0.99 999 Molarity: 0.114 COMMENTS Thermometric titrations of borax and boric acid are simple and precise. Titration time is about one minute per sample. In the "quantitative" mode of the SANDA QC Thermo Titrator, the titrated volume at endpoint is directly read from the digital display of the buret. The accuracy of results has been proven correct in many determinations, whether it be acid/base, redox or precipitations.