Pressure in the Diet CokeTM & MentosTM Reaction


Perform a series of experiments on the reaction between Diet CokeTM and MentosTM candies. Use the data to estimate what the pressure would be inside a sealed 2 L bottle of Diet CokeTM with 5 MentosTM mints.


  1. Prepare a set of bottle caps by drilling holes of varying sizes in the cap from a 2 L bottle of Diet Coke.
  2. Prepare strings of 5 Mentos by drilling a hole through them and tying them together with string. Leave about 3" of string to thread through the hole in the bottle cap.
  3. Assemble your Diet Coke/Mentos fountain.

    Construction of Diet Coke & Mentos Fountain

  4. measure the height of the spray as a function of the diameter of the hole in the cap.
  5. You can measure the height by sighting a known height and the height of the spray with a ruler, and then solving using a proportion. 

    Measuring the Height of the Spray


Determine the pressure with no opening from a graph of pressure vs. diameter of the opening, extrapolating to an opening of 0 mm.  An example with sample data is shown below:

Graph of Pressure vs. Height


Last modified: Sunday, 3 June 2012, 1:19 AM