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STEM Fest Interactive: Cranberry Experiments

Coloring Changing Cranberry Science

Cranberry juice is not only an acidic juice, but is also a PH indicator. When we stir in baking soda, which is basic or alkaline substance, we not only get a foaming reaction like you would when making a volcano with vinegar and baking soda, but the juice also changes color. It darkens from a red color to more of a purple color. When you add vinegar to the juice/baking soda solution, you make it more acidic again and the color of the juice returns to red again.


  • 100% cranberry juice - Color change shows up best with cranberry juice, but you will still get a chemical reaction with any cranberry juice blend or another acidic liquid such as lemon juice or white vinegar.
  • White vinegar
  • Baking Soda

Also needed: 2 tall clear cups/glasses, a long plastic spoon to stir with, a table protector, and a tray to catch overflow.

Dancing Cranberries

Fresh cranberries have little pockets of air trapped under the skin of the fruit, so they float in plain water. Dried cranberries do not so they sink. You can make the dried cranberries float and dance by adding carbonated lemon-lime soda. The carbon dioxide bubbles cling to the dried cranberries allowing them to rise and when the bubbles pop, they fall again. Another way to create the same effect can be used with vinegar and baking soda. Dissolve some baking soda in water, add the dried cranberries, and then add white vinegar. The vinegar and baking soda solution create carbon dioxide bubbles that again cling to the raisins and cause them to rise and fall again after the bubbles burst.


  • Dried cranberries
  • lemon-lime soda
  • baking soda
  • vinegar

Also need clear glasses or cups

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