Lab Report Requirements Data Present all data and calculations in tabular format

Question

Lab Report Requirements Data Present all data and calculations in tabular format. The data tables should be well organized, all columns/rows should be labeled, and the data formatting (sig figs) should reflect the precision of the instruments used. Calculations 1. Use the volume and concentration of NaOH, and the stoichiometry of the chemical reaction to determine the mass of Vitamin C in each sample. 2. Determine the mass percent of Vitamin C in each powder sample. 3. Calculate the average mass percent of Vitamin C in the powder samples. 4. Calculate the mass of Vitamin C in one full tablet. 5. Calculate the percent error of your work. Post-Lab Questions Com you think you went wrong. Explain exactly how over-titrating would impact your calculation of the amount of Vitamin C in the tablet? Use online resources to find the recommended daily dose of Vitamin C for a person of your age and gender. How many tablets would you need to take to meet the recommended daily dose of Vitamin C? 1. ment on your percent error. If your percent error is over 5%, please address where 2. 3.

Explanation / Answer

Analysis of Vit. C

Titration with NaOH

1 mole of Vit. C reacts with 1 mole of NaOH

Ist trial,

1. moles Vit.C = moles NaOH = 0.096085 M x (26.4 - 4.0) ml = 2.1523 mmol

mass of Vit. C = 2.1523 mmol x 176.12 g/mol/1000 = 0.380 g

2. mass % Vit. C = 0.380 g x 100/0.44 g = 86.36%

IInd trial,

1. moles Vit.C = moles NaOH = 0.096085 M x (26.3 - 6.0) ml = 1.9505 mmol

mass of Vit. C = 1.9505 mmol x 176.12 g/mol/1000 = 0.343 g

2. mass % Vit. C = 0.343 g x 100/0.44 g = 77.95%

IIIrd trial,

1. moles Vit.C = moles NaOH = 0.096085 M x (44.3 - 26.3) ml = 1.730 mmol

mass of Vit. C = 1.730 mmol x 176.12 g/mol/1000 = 0.305 g

2. mass % Vit. C = 0.305 g x 100/0.37 g = 82.43%

3. average mass % Vit. C = 82.25%

4. mass Vit. C in 1 tablet = 0.343 x 0.5/0.44 = 0.390 g [mass of 1 tablet = 0.5 g]

5. Percent error = (0.5 - 0.390) x 100/0.5 = 22%

Post-lab

1. Percent error is high in this case. The most probable reason would be incomplete dissolution of Vit C tablet in solution, which would give les amount of Vit. C to be reacted with NaOH in solution.

2. Over titrating would give higher moles of NaOH used, thus higher moles and therefore higher mass of Vit. C present in solution.

3. The daily dose of Vit. C tablet for an adult is about 75 mg/day which could be obtained by taking 1 tablet per day.

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