EXPERIMENT: STANDARDIZATION OF A THIOSULFATE SOLUTION AND DETERMINATION OF ASCORBIC ACID IN VITAMIN C TABLETS REPORT
PART A: STANDARDIZATION OF THIOSULFATE
You may neatly handwrite the answers to the calculations. However, any answers that cannot be clearly read (at the discretion of the grader) will be marked "zero."
1. What is the concentration of your iodate primary standard? Determine the uncertainty (you may ignore uncertainty in the molar mass, as it will be negligible). Show all of your work and be sure to include the correct number of significant figures.
2. Determine the number of moles of I3 - present in the analyte. Show all of your calculations in determining the limiting reactant and report your answer with the correct number of significant figures for one trial only (they should all be identical).
3. Determine the concentration of your standard thiosulfate solution. Determine the average concentration and the uncertainty (show work). Report your answer in M to the correct number of significant figures.
PART B: DETERMINATION OF VITAMIN C CONTENT
1. What mass of vitamin C is present in your tablet? Show ALL calculations for one trial only.
2. Calculate an average mass of vitamin C (using the 2-3 trials), and determine the uncertainty. Compare this to the reported amount of vitamin C on the packaging.
POST-LAB QUESTIONS -
Type your answers on a separate page and attach it to the back of your report. Hand written answers will not be accepted.
Many biological reactions are electron transfer reactions and their spontaneity can be determined by calculating the potential and ΔG of the reaction. For the following reaction, determine a) the oxidizing agent and reducing agent, b) ΔG°, and c) if the reaction is spontaneous. (You will need to use a standard reduction table to determine the E° of each half reaction.)
NADH + H+ + ½ O2 → NAD+ + H2O