How did the first peoples know which foods were safe to eat? Excellent question! Food historians make educated guesses based on ancient records and modern practices.
When water freezes its entropy decreases. This does not violate the second law of thermodynamics. The second law does not say that entropy can never decrease anywhere. It just says that the total entropy of the universe can never decrease.he entropy increases whenever heat flows from a hot object to a cold object. It increases when ice melts, water is heated, water boils, water evaporates. The entropy increases when a gas flows from a container under high pressure into a region of lower pressure.
A unique property of water is that its density increases at 4Â°C (39Â°F), just before it hits. freezing temperature. This causes water at this temperature to sink to the bottom of the. pond or lake. When water molecules do freeze, the ice is less dense than the 4Â°C water, causing it to float on the surface. The differences in density start mixing the top and. bottom layers of water. This mixing of the water layers as air temperatures become. colder is called fall turnover (Fig. 1).