2B40.57 Coke vs. Diet Coke


Density of liquid, effect of sugar content on density


When submerged in water, Diet Coke floats while regular Coke sinks. A regular Coke can is denser than water due to a large amount of dissolved sugar and sinks. A Diet Coke can replaces the sugar with a small quantity of artificial sweeteners, so it's less dense and floats.



  • [1] 10-gallon aquarium
  • [1] Can of Diet Coke
  • [1] Can of regular Coke
  • [1] Rubber hose

Classroom Assembly

  1. Use the rubber hose to fill up the aquarium a little more than halfway with water.
  2. Test whether the can of Diet Coke floats and the can of regular Coke sinks.


  1. Insert the two soft drink cans sideways into the water to make sure that no air bubbles are trapped under the can.


Additional Resources



  • Don't attempt this at home!

Last revised

  • 2020


  • Not all Diet Coke cans float. They vary enough that at least some of the "mini" 222 mL cans will sink. Test them!
  • Over time, the acid in the colas will eat through the cans. They're probably good for a year or two. The diet cola tastes weird after a while, possibly due to the instability of the artificial sweeteners.

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If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.