Which is more dense? Coke or Diet Coke?

Today, we had an experiment on density. We had to find out the density values for Regular Coke and Diet Coke. Well, this experiment will tell you which soda can will float and which one will sink in water.

But first, we have to define what this density means. Density gives us the relative "heaviness" of objects with a constant volume. This is more formally defined as "mass per unit volume." The mathematical equation for this is

Density = Mass/Volume
= g/mL or g/cc
= g/L

The units that are most commonly used for density is g/mL or g/cc (cubic centimeter), and g/L.

Density explains why oil floats in water. It is because oil has a lower density value, also means less dense, than water. Another example on density is the factual phenomenon that ice cubes float on water in a glass. This means that ice water has a lower density value than liquid water.

Let's go back to our experiment. The picture above is exactly what happened to our coke samples. The regular or classic coke sank and the diet coke floated. Now, let's relate these results to density... this property will explain what we have observed.

Comparison of:
Classic Coke	Diet Coke
355 mL	355 mL
Water = 355 g	Water = 355 g
Sugar = 39 g	Sugar = 0 g
Nutra Sweet = 0 g	Nutra Sweet = 0.1g
Tot. Wgt. = 394 g	Tot. Wgt. = 355.1 g

Calculating the density value for regular coke will give us

density = mass/volume
= 394 g/355 mL
= 1.11 g/mL

while the density value for diet coke is

density = mass/volume
= 355.1 g/355 mL
= 1.00 g/mL

The computations show us that diet coke has a lower density value as compared to regular coke. This explains why the diet coke floated on water and the regular coke sank.

In chemistry, density values for many substances are compared to the density value of water. So if your sample has a lower density value as compared to water, then it surely will be on top of the water in a container.

This is a cool experiment to do at home.

Take note:

* Do not forget to take a look at the amount of sugar that they put in regular coke, 39 grams! Wow, you will surely have sugar rush after drinking lots of soda in a day!

* Pictures and table courtesy of Charles E. Ophardt