Soda Geyser

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Author: Sofia PC

Grade Level: 6th-9th; Type: Physical Science


To discover which candies will create a soda geyser!

Research Questions:

  • What is carbonation?
  • How do different substances (in this case, candy) interact with carbonated water?
  • What is nucleation?

Carbon dioxide (CO2) is present in the air we breath and in the carbonated soda we drink. In soda, the carbon dioxide gas (CO2 ) has been dissolved, a process called carbonation that results in soda's signature fizz. This happens because gas molecules are kept in the airtight can under lots of concentrated pressure and will fight to escape when you crack it open, which lowers the pressure and creates a fizz. But this normally gentle process turns violent if we drop certain candies into the soda, because the gelatin and gum arabic in the dissolving candy helps the gas molecules to escape even more quickly, in another process called nucleation. The right candy will cause the right soda to explode!


  • Mentos mints
  • Tic-Tac mints
  • Altoids mints
  • Smarties candy
  • Two-liter bottles of Diet Coke Cola
  • Two-liter bottles of Regular Coke Cola
  • Two-liter bottles of Sprite

Experimental Procedure:

  1. Go outside.
  2. Set the bottles of Diet Coke Cola, Regular Diet Coke, and Sprite on a flat surface.
  3. Drop a few mentos immediately after opening each one. Stand back and watch what happens.
  4. Repeat the procedure three times, with Tic-Tacs, Altoids, and Smarties. Compare the reactions
  5. Record your results.
  6. Compare the ingredients of the candies and the sodas. What combinations produce the most explosive result?

Terms/Concepts: Porosity; bubbles; carbonation; nucleation


General Chemistry Online: Why do Mentos mints foam when you drop them into soda pop?

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