Oct. 5, 2005

The Great Ketchup Caper

Test a series of acids and bases on a ketchup stain to learn more about molecules, acids, bases, solutions, and chemical reactions.

Description:

A series of acids and bases are used to attempt to clean a ketchup stain.

You Will Need:

1. white T-shirt stained with ketchup
2. lemon juice
3. water
4. baking soda
5. club soda
6. clear bowls, plastic cups, or small cups for mixing

Instructions:

During this activity, you will try different cleaning methods using mild acids and bases, predicting, testing, and measuring results.

In separate containers, pour small amounts of lemon juice and club soda.

Make a baking soda and water solution by mixing one teaspoon of baking soda with water.

Predict which "stain fighter" will work the best. Drop a scrap of the stained shirt into each container and stir for a designated time (30 to 60 seconds) with a spoon. Compare results.

Content:

Lemon juice (an acid), baking soda (a base), and club soda (an acid) each react with the ketchup stain, which is also acidic. Acids and bases are added to soaps and detergents to improve the cleaning process. A chemical reaction occurs between acids and bases; this can be evidenced by mixing the acidic substances with the baking soda, resulting in foaming as the base acts to neutralize the acid.

Teacher's Notes

Activity excerpted by permission of the Chemical Educational Foundation (www.chemed.org) from You Be The Chemist. For additional information about these activities and lesson plans, see www.chemed.org/Kit.html.

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