Analysis of Ascorbic Acid Formulation - Results Sheet Standardisation, of -0.1 M KOH: Concentration of HNO, = 0.1013 +-0

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Analysis Of Ascorbic Acid Formulation Results Sheet Standardisation Of 0 1 M Koh Concentration Of Hno 0 1013 0 1 (80.1 KiB) Viewed 16 times

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Analysis of Ascorbic Acid Formulation - Results Sheet Standardisation, of -0.1 M KOH: Concentration of HNO, = 0.1013 +-0.0002 M Aliquot volume of HNO, = 20 mL Burette Reading Titre, 1 Titre 2 Initial (cm³) 0.50 mL 0.00 mL Final (cm³) 20.80 mL 19.14 mL Titre (cm³) 20.30 mL 19.14 mL Trial 1.81 mL 20.94 mL 19.13 mL Average titre of NaOH = Analysis of Ascorbic Acid: Burette Reading Mass of vial & powder (g) Mass of vial & residue (g) Mass transferred (g) Burette Reading Initial (cm³) Final (cm³) Titre (cm³) Flask 1 15.1897 14.7905 0.3992 Flask 1 0.51 19.31 18.81 19.14 ± 0.02 Use your best 3 titres) Flask 2 14.8439 14.4546 0.3893 Flask 2 0.00 18.10 18.10 Flask 3 15.0653 14.6688 0.3965 Flask 3 0.00 17.75 17.75 Titre 3 1.00 mL 20.16 19.16 mL mL (or cm³) Flask 4 16.7644 16.3543 0.4101 Flask 4 0.00 18.89 18.89
Calculations For the standardisation of KOH, use your titration results (the average of your concordant titres against the HNO3) to calculate the concentration (in units of molarity) of the ~0.1 M KOH solution. Combine this knowledge with the masses and titres of your vitamin C analysis to determine the mass of ascorbic acid present in each of your 4 samples. Using the best 3 results, calculate the percentage by mass of ascorbic acid present in the formulation (grams of acid per 100 grams of formulation).
Show each calculation step for your first analysis only (flask 1). Then complete the results summary table, showing answers for all 4 flasks. Example calculation, Flask 1 Calculate the number of moles of KOH required to titrate the powder sample: Number of moles of ascorbic acid titrated by the KOH: Mass of ascorbic acid present in powder sample: Percentage ascorbic acid in the powder formulation: Calculation Summary Table Moles of KOH required to react with powder (mol) Mass of ascorbic acid in the powder (g) Percentage ascorbic acid Tick box to show your 3 most concordant results Average of the best 3 results= Analysis 1 Analysis 2 Analysis 3 Analysis 4 ± 14
What major assumption are you making about the reaction taking place in this experiment between the formulation and the base? (see p8.2 for assistance) Can the top-loading balance be used to determine accurate masses? What is the purpose of using the top-loading balance? Do you expect the titre to be the same for each of your 4 ascorbic acid analyses? Explain.