1. The chemical composition of water contains11.1%hydrogen and 88.89% oxygen. By volume, there are two parts of hydrogen and one part of oxygen. Water molecules that exist alone are called single water molecules, and when water molecules associate, they can form double water molecules, triple water molecules and so on.
Like other substances, water increases in volume and decreases in density when heated. The density of pure water at 0℃ is 999.87kg/m3, and that of water at boiling point is 958.38kg/m3, which is 4% lower.
3. At normal atmospheric pressure, when water freezes, its volume suddenly increases by about 1 1%. When the ice melted, its volume suddenly became smaller again.
4. The freezing temperature of water decreases with the increase of pressure. Every increase of 65438 0.30 atmospheric pressure will reduce the freezing temperature of water by 65438 0 degrees Celsius.
5. The boiling point of water changes linearly with pressure. The boiling point increases with the increase of pressure.
6. The heat capacity of water is less than that of hydrogen and aluminum, but higher than that of other substances. Water transfers less heat than other liquids.
: water (h? O) It is an inorganic substance composed of hydrogen and oxygen, and it is a colorless and odorless transparent liquid at normal temperature and pressure. Water is one of the most common substances, an important resource for all life, including human beings, and the most important component of organisms. Water plays an important role in the evolution of life.
People's understanding of aquatic products has a long history. In China's ancient and western simple material views, water was regarded as the basic component, and water was one of the five elements in ancient China. There was also water in the four-element theory of ancient western countries.