Virtual Lab: Determination of Vitamin C in a Peach

This assignment uses Virtual Lab software which offers interactive, simulation-based exercises that can mimic laboratory experiments seen in Chem 324. The experiment can be found at chemcollective.org/activities/autograded/130. Please fill in the following document and submit.

PreLab

Read the introduction of the experiment located on the webpage given above to answer the following questions.

1. In this titration what chemical species is reacting with the ascorbic acid? This species cannot be directly added to solution, explain where it comes from.

2. From equation 2 what species is being reduced? What species is being oxidized?

Experiment

The goal of this lab is to determine the amount of ascorbic acid in 1 medium peach. Using your expertise in titrations you will design the titration with the help of the information in the introduction. “You will be titrating with potassium iodate into a solution of ascorbic acid. In order for the reaction to occur, the ascorbic acid solution must also contain: 5 mL of KI solution, 4 mL of the HCl solution and 3mL of the starch solution. At the endpoint, the solution will turn a very dark purple color.” The simulation also includes a solution of ascorbic acid with a known concentration, you should use this to double check your experimental methods and calculations to make sure you are getting the correct value for ascorbic acid.

Procedure

Write a detailed step-wise procedure for your experiment. Be sure to include the name of all glassware and volumes of solutions reported to the correct number of significant figures. The procedure should be written as if you were in lab performing the experiment and detailed enough to replicate in lab. Make sure to include a table with the initial and final volumes from your buret. In a real-life lab, you would repeat the titration in triplicate, it is fine to complete the titration only once in the simulation. This procedure should be typed in the space below (add more space as necessary).

Calculations

Using the data from the Virtual Lab, determine the amount of ascorbic acid (in mg) found in 1 medium peach. Insert all work as equations in the space below.