We use detergents to clean many things, clothes, dishes, even cars. Dishwashing liquid is the most common detergent in the home. You might be surprised to learn that in the wrong places this great cleaner has a downside.Materials:
Water
Large bowl
Waxed paper
Self-sealing plastic sandwich bag
Dishwashing liquid
What to Do:
Fill the bowl with water.
Crumple a large piece of waxed paper and stuff it into the sandwich bag. Seal the bag.
Float the bag on top of the water. Add several big squirts of dishwashing liquid to the water and observe. Does the bag begin to sink?
Action, Reaction, Results:
One reason that the bag floats on the surface of the water is that it has an oily coating that makes it water repellent. Detergent in the dishwashing liquid breaks up the oily coating and the bag begins to sink. Do all detergents work the same? Does it take the same amount of time for the bag to sink with different detergents?
From our experiment we can see that detergents can cause problems. Detergents in a natural water supply can cause harm to wildlife, too. For example, detergents can make water birds’ feathers less repellent to water. When hiking or camping it is important not to use detergents in or near lakes, rivers, ponds or streams.
Have a love for exploring the world around you? Sign up to help with the science fair. Contact Amy Oliver (amyroliver@gmail.com) or Anca Stepan ( ) to join the fun.
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