Question

During the winter months, water on the surface of a pond will typically freeze and this ice acts as an insulator for the water beneath it. As a result, aquatic life is able to survive during the cold winter. The reason that this water expands upon freezing is due to

Answer 1

Step-by-step explanation:

From 0° to 4° water contracts so its density increases. Above 4°C, water exhibits the expected expansion with increasing temperature. The density of water reaches its maximum value of 1000 kg/m³ at 4°C.

We can use this unusual thermal expansion behavior of water why a pond freezes slowly from the top down. When the atmospheric temperature drops from 7°C to 6°C ,say the water at the surface of the pond also cool and consequently decreases in volume. This means the surface water is more dense than the water below it, which is not yet cooled nor decrease in volume. As a result, the surface water sinks and warmer water from below is forced to the surface to be cooled, a process called Upwelling. When the atmospheric temperature is between 4°C and , however, the surface water suspends as it cools, become less than the water below it. The sinking process stops and eventually the surface water freezes. As the water freezes, the ice remains on the surface because ice is less dense than water. The ice continues to build up on the surface, and water near the bottom of pond remains at 4°C. Further, the ice forms an insulating layer that slows heat loss from the underlying water, offering thermal protection for marine life.

Answer 2

When water freezes, the hydrogen bonding that creates its hexagonal shape causes the water molecules to expand out and take up more volume. As a result, its less dense than liquid water and it floats.