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Just for interests sake, on a Saturday night

  1. May 28, 2016 #1
    Why is there an excess of foam when I add ice to rum and coke?

    When I add ice to vodka and sprite/lemonade there is a short burst of foam which quickly dissipates.

    What causes the reactions to differ? Sugar?
  2. jcsd
  3. May 28, 2016 #2


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    Coke is foamier than Sprite even without alcohol.
    It's way less fun to do this experiment than yours, but such is the sacrifice of the scientist.o0)

    As a Diet Coke drinker, I can tell you it is pretty foamy too, so I don;t think it's about the sugars themselves.
    I do believe that cola is denser than Sprite - it has a higher syrup to water ratio.
    Last edited: May 28, 2016
  4. May 28, 2016 #3


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    evidence suggests I am only partially right. While Coke is denser than Sprite, Diet Coke is not.

    Density in g/mL
    Cola: 1.11
    Sprite: 1.037
    Diet Cola: 1.00
    Diet Sprite: .9965


    This shows a trivial way to measure relative density:
    Just float them in water.
    If you need a finer-tuned measurement, just add a measured amount of alcohol until they sink, or add salt to until they float.
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