Thermodynamics

Negative Expansion Coe cient of Water (4A20.30) -a 2 liter ask of colored water with a glass tube inserted through the stopper is kept in a bath of ice water until the temperature of the water in the ask has fallen to 0° C. The water level in the vertical tube is noted, and the ask and tube are removed from the ice bath. As the temperature of the ask water rises above 0° C, the water level in the tube drops until the water has warmed to about 4° C, the temperature of maximum density, then begins to rise. Demonstrates why ice oats, and always forms at the top surface of the water.