Ice floats because it's less dense than liquid water, which is unusual for most substances.
Here's a breakdown of why:
Why Most Things Sink When Solid
- Typically, when substances freeze, their molecules pack more closely together.
- This closer packing means the solid form is more dense than the liquid form, causing it to sink.
- Think of a rock. The solid rock is denser than the liquid form (lava), and therefore sinks in lava.
Water is Different!
- Water is unique! When it freezes, its molecules arrange themselves in a way that creates extra space. As the video states, "that extra space between molecules makes a solid ice cube less dense than liquid water"
- This special arrangement results in ice being less dense than liquid water.
- Since ice is less dense it floats on top of the more dense liquid water.
Key Differences in Density
| State | Density |
|---|---|
| Liquid Water | Higher |
| Ice | Lower |
Practical Implications
- Ice on Lakes and Oceans: Ice floats, forming an insulating layer on top of bodies of water. This prevents the water below from freezing, which is essential for aquatic life to survive.
- Icebergs: Icebergs float, which allows them to move and melt gradually instead of sinking to the bottom of the ocean.
- Ice Cubes in Your Drink: Ice cubes float in your drink because of this density difference.
In short, unlike most materials that become denser when they freeze, water expands and becomes less dense making ice float.
