What characteristic of water is exhibited during a cold winter, people being able to cut a hole in the ice on a lake and catch living fish?
2 Answers
Water is one of the few substances that decrease in density when changing from a liquid to a solid.
Explanation:
Water forms hexagonal crystals due to the intermolecular bonding between the Hydrogen and Oxygen atoms in the water molecule.
The hexagonal crystal formation pushes the water molecules further apart in the solid state than in the liquid state.
Because the molecules are further apart, the volume increases, so solid water (ice) is less dense than liquid water. This causes the solid water to form on the surface of a body of water. A thick sheet of ice may form on the surface of a lake, river, or ocean ( like the arctic). The water underneath the ice remains liquid, as the ice floats on the top of the water.
The ice insulates the water underneath. The fact that water freezes and turns solid on the surface allows fish and other organism to survive underneath the surface ice. If water was like most substances the solid form would be more dense than the liquid form. The ice would form on the bottom of the body of water , increasing until there was no liquid. This would mean that there would also be no living organisms left alive in the now solid water liquid.
The characteristic that the density of ice is less than that of cold water.
Explanation:
As water cools in the lake it mostly happens by evaporative cooling, and in small extent by conductive cooling.
When water temperature reaches 4 degree Celsius, since 4 degree Celsius water has the highest density, it sinks to the bottom.
The closer the temperature to the freezing point the lower the water density, so all the colder water rises to the surface.
Ice has even less density, so the lake freezes on the top but it takes a very long time to freeze to the bottom.
So the fish are swimming under the ice happily, until the whole lake freezes to the bottom due to conductive cooling.
