Chemical Concept Demonstrated: Density
|A can of Coke/Pepsi and a can of Diet Coke/Pepsi are added to a 4-L beaker filled with 3-L of water.|
The regular can sinks. The diet can floats.
Diet drinks are less dense than their regular counterparts because the sweetener added to them is "sweeter" than sugar. Less of the artificial sweetener is necessary to make a diet cola taste as sweet as a regular cola, so the final density is less.
Regular Coke/Pepsi has a higher density than water, so a can of it sinks in water. Diet Coke/Pepsi has a lower density, so a can of it floats.