The specific gravity of water is the density of water, and the specific gravity of water is 1000 kg/m3 (t=4℃). Density is a measure of mass in a specific volume. Density is equal to the mass of an object divided by its volume, which can be expressed by the symbol ρ (pronounced [r]). In the international system of units and China's legal units of measurement, the unit of density is kilogram per cubic meter, and the symbol is kg/m3.

When water is used as the reference density, that is, 1g/cm? As a reference density (the density of water at 4℃), it used to be called specific gravity. The relative density is generally 1 when the water is taken at 4℃, and then divided by the density of another substance. The relative density just has no unit, and the value is the same as the actual density. For example, the relative density of methane is 0.555. It is very convenient to use (under normal temperature and pressure) and can also be used for calculation.

The essence of water

Water (chemical formula h? O), an inorganic substance composed of hydrogen and oxygen, is nontoxic and drinkable. At normal temperature and pressure, it is a colorless and odorless transparent liquid, which is called the source of human life and an important substance to maintain life, also called hydrogen oxide.

Water is one of the most common substances on the earth, and about 7 1% of the earth's surface is covered with water. It is an important resource for all life, including inorganic compounds and human beings, and it is also the most important component of organisms. Although its content in the air is small, it is an important part of the air.

Pure water has very weak conductivity and belongs to extremely weak electrolyte. Water in daily life has obvious conductivity because it dissolves other electrolytes and has more anions and cations.

The above contents refer to Baidu Encyclopedia-Water.