Physical meaning is: the mass of 1 m3 water is 1.0× 10? Kg is 1t (ton).
Variation of water density
The maximum density of water is 1000kg/m3 at 3.982℃. When the temperature is higher than 3.982℃ (which can also be ignored as 4℃), the density of water decreases with the increase of temperature. When the temperature is 0 ~ 3.984℃, water contracts and expands, and the density increases with the increase of temperature.
When water does not freeze at 0℃, most water molecules are (H? O)3 exists. When the temperature rises to 3.98℃( 10 1.375kPa), most of the water molecules are (h? O)2 exists as an associative molecule. The space occupied by molecules is relatively reduced, and the density of water is the highest at this time.
When the water temperature drops to 0℃, water turns into ice. When water freezes, almost all molecules associate to form a huge associated molecule. The arrangement of water molecules in ice is that each oxygen atom has four hydrogen atoms as its neighbors and two hydrogen bonds. This arrangement leads to an open structure, and there are large gaps in the structure of ice, so the density of ice is inversely proportional to the density of water at the same temperature.
Extended data:
Density application
1, identify the materials that make up the object.
Density is one of the characteristics of matter. Every substance has a certain density, and the density of different substances is generally different. So we can use density to identify substances. The method is to measure the density of the measured substance, and compare the measured density with the density of various substances in the density table, so as to identify what substances the object is made of.
2. In agriculture
It is an important foundation of density. It can be used to judge soil fertility in agriculture. Soil with more humus is more fertile, and its density is generally 2.3× 10? Kilogram/meter? .
When selecting seeds, we can select seeds according to the ups and downs of seeds in water: full and strong seeds sink due to high density; The seeds of shriveled shells and other weeds float on the water because of their low density. In industrial production, such as the production of starch, potatoes are used as raw materials. Generally speaking, potatoes with more starch have higher density, so the yield of starch can be estimated by measuring the density of potatoes.
3. In industry
Before casting metal, the factory needs to estimate how much metal needs to be melted, and can calculate the required metal amount according to the volume of the mold and the density of the metal.
Baidu encyclopedia-water