This 50 minute lab allows students to determine the amount of vitamin C in a standard solution and in three juices. They then determine how much of one juice will give them their daily recommended dose of Vitamin C.
The teacher instructions give the set up and a list of the issues you might have. One of those issues will have to do with the concentration of iodine that you use depending on what's available to you, and the amount of ascorbic acid in the juices you choose. I give you trouble shooting tips for both to make this lab run smoothly. You’ll want to set this lab up and run it yourself before your students do. Some juices have very high ascorbic acid content and you have to make adjustments for it.
This is a nice way to open your unit on solutions and molarity. Each reaction turns dark blue when it reaches the end point. This is a microscale experiment so it goes quickly and there is little material to go into the trash. My students get really excited by it and want to test other products like their favorite lemonade.
You’ll need small amounts of ascorbic or citric acid, starch, iodine solution or iodine crystals, and fresh solutions of pineapple, orange and apple juice.