The water anomaly
Ice consists of water. But if it consists of water only, why does it always swim on the surface of the water? To find out what is changing, the following experiment can be done.
A plastic cup is filled to the brim with water (see the picture on the left) and is then put in the freeze compartment of the fridge for several hours.
When the cup is removed from the freeze compartment, we do not only have solid water instead of liquid water, but we can also notice another change (see picture on the right).
What has happened to the mass of the water, when it was freezing to ice? And what has happened to its volume? What does this mean in terms of the density? How would you describe the result? (choose one possibility from below)