Why Ice Floats

Q. Imagine a frozen lake in winter. Is there anything living in this lake during wintertime?

A. A variety of things… fish, turtles, many different plants.

Why Ice Floats

Q. What would happen to these organisms if ice were more dense than liquid water?

A. The ice would sink as it formed instead of forming a protective shield for the organisms in the water below.

• http://ed.ted.com/lessons/why-does-ice-float-in-water-george-zaidan-and-charles-morton

Why Ice Floats

• Frozen water and liquid water have the same mass BUT the water takes up more space as ice than it did as a liquid. (due to the gridlike crystal structure)

• This means that ice is less dense than liquid water.

• Iced tea!

Specific Heat

• Specific heat is the amount of heat needed to increase the temperature of a certain mass of a substance by 1° C.

• Water has an unusually high specific heat which means that it requires a lot of heat to increase its temperature.

Think about this…

• On a hot July day, the air, sidewalk, and sandy beach are HOT! But if you jump into a pool or the ocean the water is cool.

• If you were to go for a swim at night, the water is warm compared to the cool air.

Why does this happen?

Because…

• In the summer, the sun’s heat warms the land more quickly than the water. The warm land heats the air above it.

• Remember that it takes more heat to increase the temperature of the water.

• At night, the land/air cools off faster than the water does.

Words Worth Knowing (ISN #39)

• Polar molecule• Surface tension• Capillary action• Solution

• Solvent• Evaporation• Condensation• Specific heat