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Lemon Chemistry: An Acid Base Experiment

Kari Wilcher runs a great blog. She was looking to teach her pre-school children about the Scientific Method while trying out some kitchen chemistry at the same time. Her plan was to show a dramatic acid-base reaction using lemons, baking soda, and a little dish soap. She writes:

“I firmly believe that children are never too young to be exposed to the scientific method and should follow it. I have found that the scientific method is very easy for them to understand, and follow, when presented to them in a simple way. I like to use a rebus (picture) to help my non-readers understand the directions. I also use these “big” words: data, hypothesis, prediction, and observation. We, including Momma, wear goggles (from the dollar store) and a lab coat (a.k.a. dad’s white button up shirt) because we are real scientists doing real science experiments…and it just makes us cool.”

You will need:

  • Fresh Lemons
  • A knife
  • A small measuring cup & measuring spoon
  • Baking Soda
  • Liquid dish soap
  • A clear cup for the reaction

What to do:

  1. Roll the lemons on the counter like dough. This releases the juice inside the lemon.
  2. Cut the lemon in half (adults only, please) and carefully squeeze out the juice into a small measuring cup. Note how much juice was created from each lemon and put the juice aside.
  3. Into the empty glass place 1 Tablespoon of baking soda.
  4. Add 1 teaspoon of liquid dish soap to the baking soda. Stir these up a bit.
  5. Pour the lemon juice into the cup and stir. Now watch the lemon suds erupt!

How does it work?
This is a classic example of an acid-base reaction. This is often done with vinegar and baking soda, but we liked Kari’s “lemon twist.” The baking soda (a base) and the lemon juice (an acid) combine to release Carbon Dioxide gas. The liquid soap turns the bubbles into a foam that often erupts right out of the glass.

Try it out and let us know how it goes!


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