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Does Diet Coke Really Produce the Best Results?

Believe it or not, research scientists have actually concluded that Diet Coke produces the best stream of flying soda (much to the joy of the Mentos Experiment enthusiasts). I received an email from Dr. Joe Maglaty, Director of Education Outreach from the Merck Institute for Science Education with this information:

I recently came across an article that you may, or may not, be aware of. In the April issue of the Journal of Chemical Education, a chemistry professor from Illinois State Univ. took on the analytical process for showing gas solubility in aqueous solution – that is, how much carbon dioxide (CO2) is released from soda (pop) using ultrasonic energy. Since ultrasonic waves provide millions of nucleation sites at the wave nodes inside the soda bottle, this technique is much more effective in releasing CO2 than any physical substance, such as Mentos or Lifesavers. The quantitative results are quite impressive, with the bottom line being that Diet Coke at room temperature is the best way to eject most of the soda into a fountain.

The Journal of Chemical Education article probably gives you more information that you’d ever want on the topic. A PDF of the full text is also at this location. With this phenomena of releasing carbon dioxide quickly from a gas/liquid mixture, more teachers should take advantage of this opportunity to explore this science with their students. Everyone should share in this excitement and be involved with inquiry based, hands-on and minds-on science activities that helps us understand and learn from the world around us.

29 replies
  1. Daray
    Daray says:

    I am a Pre-K teacher putting on a Science camp in Texas this week. Let me assure you, clear diet drinks only produce a gurgling stream of about 3-4″. I was so disappointed not to have the 8″ shoot I was expecting. It was a real let down for the kids. I promised them we would try it again in two days with diet COKE this time. I used the clear soda hoping it would not stain their clothes when it sprayed out … my bad for not tryng the experiment ahead of time with the clear soda!

    Reply
  2. Margaret Newsom
    Margaret Newsom says:

    I taught a science camp for 3 & 4 year olds in Houston and we tried pretty much every soda out there over the course of a week…it became a daily ritual. We concluded that diet Coke does indeed soar the higest (one student wanted to know if that’s what makes rockets go…). Diet Sprite came in second, with orange soda performing at the lowest height – only about two feet. We tried funneling the Mentos in, using a test tube, and on string – the test tube worked the best for us.

    We had a lot of fun, but the best part was how excited the children were about these activities and how thrilled they were to move on to related activities. I teach at a school where the children come in very prepared academically, but many missing the joy of discovery and a desire to experiment with materials. Thanks for so many wonderful ideas shared here.

    Reply
  3. Amy Beaman
    Amy Beaman says:

    And it’s true! Our scientific research……outside my parent’s home on Mother’s Day with many friends, family and curious neighbors watching, proved the same thing.
    Most were betting on whether we’d be able to drop in the Mentos w/o being completely drenched! And we also found that if you don’t get all the Mentos in, that does affect the quality of the “plume”!

    Thanks Steve! Another example of if you get it to the dinner table, you’ve won!

    Reply
  4. Steve
    Steve says:

    I received an email with this information…

    I have some additional information on this experiment. I’m pretty sure the reason that Diet Coke works better than regular is because the diet sodas contain more carbonation than regular sodas. I’ve worked in several fast food places, and the diet beverage syrups are always mixed with a higher carbonated water to syrup ratio than the regular sodas. For example, Coke is mixed at 5:1, and Diet Coke is mixed at 5.2:1

    Dustin Oliver

    Reply
  5. JGoodwin
    JGoodwin says:

    Hey, Amber! It’s Diet Coke, not regular Coke. the Diet Coke works best because regular cola doesn’t have as much carbonation as the diet colas have. Thanks for asking!

    Reply
  6. jake rizner
    jake rizner says:

    hey, im doing a science fair project. I want to use three different types of diet soda and see which one shoots the highest. How can i measure this and is this a good experiment for the coke in mentos combination?

    Reply
  7. Cassie
    Cassie says:

    hi, I am doing a science fair project. Is it better to test the temperatures of different sodas – hot, room temperature or cold or to measure the explosion or different types?

    What is the best way to measure the explosions and record them?

    Reply
  8. shay
    shay says:

    yeah i just did this project yesterday and diet coke shoots way higher then regular coke because of the caffaine and more…but i had a blast and apparently so did the diet coke lol.it was fun i ate the extra mentos left over also ….yay you should try it yourself and see how funn it really is and you learn a lot from this experimentt.

    Reply
  9. lars
    lars says:

    I am doing a science project, and i think adding dry ice to the mentos and diet coke combination might exceed average heights. I don’t know what would happen.

    Reply
  10. Steve Spangler
    Steve Spangler says:

    Works great… but it’s better with Diet. Diet Coke contains aspertame and potassium benzoate, chemicals that help bubbles form easily. However, the best reason for using any diet soda is because there’s no sugar – it’s not sticky. When we do a huge geyser demo at a conference, we’ve found that Diet Coke with Splenda shoots the highest.

    Reply
  11. Ryan
    Ryan says:

    best with mint or fruit mentos? Trying to make a mentos and coke rocket. Also, I’ve already bought a bottle of regular coke. Is that still any good or should I just buy diet?

    Reply
    • Susan Wells
      Susan Wells says:

      We’ve always used the mint Mentos due to their porous surface. Trying the fruit Mentos would be an interesting experiment. Diet Coke has the best track record, but yes, regular Coke will work too. Good luck!

      Reply
  12. noah
    noah says:

    hi this is noah, 6th grade,will u answer question about the science fare that i have concerning to the geyser of soda. For instance:

    How do i measure how hi the soda goes and which size of soda can can i use

    Reply
    • Susan Wells
      Susan Wells says:

      Hi Noah – The best way to measure the height of the geyser is to place measurements on a wall. Measure every foot and mark it 1′, 2′, etc to about 6′. Then launch your geysers and watch how high they go. It’s good to work with a partner so you can launch the geysers and have someone to note the height. They go fast! As for size, you choose the size. Our favorite size is the 2 liter bottles, but you will get a great eruption with any size. Just make sure all of the sodas that you test are all the same size and you use the same amount of Mentos so you can correctly compare the height between each one. Good luck!

      Reply
  13. Mike
    Mike says:

    Hello Steve ! Has anybody tryed Rootbeer ? I know it has to do with the amount of CO2 [ which Diet coke has alot of ] I was just woundering root beer must have alot to get all that foam.

    Reply
  14. sheeps
    sheeps says:

    Thanks everyone! your comments proved helpful for my 7th grade science fair project. Glad it is a fun easy project to do!

    Reply

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