Friday, June 13, 2008

Science Camp 2008: Day 4

Science Camp 2008 is done. What a week.

Today, we did some food chemistry. We tested the vitamin C content in various citrus fruits. First, the campers added a known ascorbic acid solution to some 2,6-dichlorophenolindophenol. The loss of color indicated the endpoint. Then they squeezed the juice from a lime, lemon, orange, and grapefruit and tested the juice. From our most crude experiment, we found that oranges have the highest concentration of vitamin C followed by lemon, lime and then grapefruit. This is probably not a reliable result, but it was a result.

The demo today was gummi bears in molten potassium chlorate (KClO3) and thermite.

The thermite reaction is great. It is a mix of 3 parts iron (III) oxide and 1 part aluminum powder. This is placed in a clay flower pot and ignited. The ignition is difficult. There are a few traditional methods. These include Mg fuse or KMnO4 and glycerol, but both are unreliable. I have adopted a much more reliable method. Since I typically do the gummi bear in molten KClO3 at the same time as the thermite (since both require a trip to the campus fire pit) I once wondered if the gummi reaction could ignite thermite. Yes it can.

I place the thermite mixture in a clay flower pot and make a depression in the mixture. I place a few grams of KClO3 and melt it with a propane torch. When is it mostly melted, I add the gummi bears. They react and then thermite becomes ignited. So far, I'm 4 for 4 using this method.

Hopefully, pictures will appear soon.

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