B. Analysis of Vitamin C tablet Mass of pill __.58__ g Trial 1 Trial 2 Trial 3 T

Question

B. Analysis of Vitamin C tablet

Mass of pill __.58__ g   Trial 1       Trial 2       Trial 3

Titration

Final reading       _____93.3___   ____96.7__   ___98_____

Initial reading       ___1.5_____   ____4.24____   ____4____

Volume of Iodine soln   ____91.8____   ____92.46____   ____94____

Calculations

Moles of I2       ________   ________   ________

Moles of Vit C       ________   ________   ________

Volume of Vit C       ________   ________   ________

Molarity of Vit C   ________   ________   ________

Grams of Vit C       ________   ________   ________

Determine the mass of Vitamin C in your pill

(Experimental mass / initial pill mass) X 100 = _______%

STOCKROOM PROVIDED SOLUTIONS:

Iodine solution: (0.005 mol L?1).

Starch indicator solution: (0.5%).

Titration

1. Pipette a 5 mL aliquot of the stock unknown solution into a 250 mL conical flask and add about 50 mL of distilled water and 1 mL of starch indicator solution.

2. Titrate the sample with 0.005 mol L?1 iodine solution. The endpoint of the titration is identified as the first permanent trace of a dark blue-black color due to the starch-iodine complex.

3. Repeat the titration with further aliquots of sample solution until you obtain concordant results (titres agreeing within 0.1 mL).

Perform steps 1, 2, and 3 for unknown Vitamin C sample (A, B, or C provided from the stockroom).  

Perform steps 1, 2, and 3 for unknown commercial Vitamin C pill.

Please help how to solve? I also need help on part B

REPORT SHEET: OXIDATION-REDUCTION TIRTRATIONS EXPERIMENT Trial 2 A. Standardization Trial 1 Unknown_ A (A, B, or C) Volume pipetted Titration Final reading Trial 3 5ml 74 Initial reading Volume of lodine soln 65m61 Calculations Mols of I Mols of Vit C Molarity of Unknown Average Molarity 70

Explanation / Answer

Concentration of I2 stock solution is 0.005 mole/ Liter

Trial 1:

Moles of I2 : Volume of I2 solution * Molarity = 0.065 Liter * 0.005 mol/ Liter = 0.000325 mole

Moles of Vit C : Moles of Vitamin C = Moles of I2 = 0.000325 mole

Volume of Vit C: 5 mL

Molarity of Vit C : 0.000325 mole/ 0.005 L = 0.065 M

Trial 2:

Moles of I2 : Volume of I2 solution * Molarity = 0.061 Liter * 0.005 mol/ Liter = 0.000305 mole

Moles of Vit C : Moles of Vitamin C = Moles of I2 = 0.000305 mole

Volume of Vit C: 5 mL

Molarity of Vit C : 0.000305 mole/ 0.005 L = 0.061 M

Trial 3:

Moles of I2 : Volume of I2 solution * Molarity = 0.07 Liter * 0.005 mol/ Liter = 0.00035 mole

Moles of Vit C : Moles of Vitamin C = Moles of I2 = 0.00035 mole

Volume of Vit C: 5 mL

Molarity of Vit C : 0.00035 mole/ 0.005 L = 0.07 M

Average molarity : (0.065 + 0.061 + 0.070)/ 3 M = 0.0653 M

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