Drinking Water

Water

water

Water (chemical formula: H2O) is an inorganic substance composed of two elements, hydrogen and oxygen. It is a colorless and odorless transparent liquid at normal temperature and pressure. Water is one of the most common substances on earth, an important resource for the survival of all life, including humans, and the most important component of living organisms. Water plays an important role in the evolution of life. Mankind began to understand water very early. In the ancient and simple views of material in the East and West, water was regarded as a basic constituent element. Water is one of the five elements in ancient China. Seventy percent of the human body is water.

Main article: Water resources

Drinking water

Drinking water from the tap

Water is an essential substance for any living things and living organisms on the earth. Water-scarce soils cannot breed organisms. Fresh water is also an essential element for irrigation and breeding of terrestrial organisms. The source, conservation, storage, and utilization of fresh water are important global issues.

The total water reserves on the earth are about 1.36x1018m3, but except for salt water resources such as the ocean, only 2.5% is fresh water. Freshwater mainly exists in the form of glaciers and deep groundwater. Freshwater in rivers and lakes only accounts for 0.3% of the world's total freshwater.

The World Meteorological Organization pointed out in early 1996: Water shortage is the primary problem facing cities around the world. It is estimated that by 2050, 46% of the world ’s urban population will face water shortage. For regions with scarce water resources, water has exceeded the range of living resources and has become a strategic resource. Due to the scarcity of water resources, the possibility of a water war breaking out is becoming higher and higher.

In order to make the whole world concerned about the shortage of fresh water resources, the 47th UN General Assembly decided to designate March 22 every year as "World Water Day".

In the early days, people would use groundwater for extraction, but the use of groundwater would cause subsidence and damage the underground structure, causing permanent damage that could not be restored, and may also block groundwater, so many countries have legislation prohibiting the use of groundwater

Water solution

Water can be used to dissolve many substances and is a good inorganic solvent. A solution using water as a solvent is called an aqueous solution. Use "aq" as a symbol, such as "HCl (aq)". It is particularly important to note that, unless otherwise specified, "xx solution" refers to an aqueous solution of "xx". Any solution containing water must be called "xx aqueous solution", that is, regardless of the ratio of solute to water, as long as there is water, water should be used as a solvent.

When a substance is dissolved in water, ionic compounds ionize in water and exist in an ionic state. Such a solution is generally transparent. When molecules dissolve in water, some can react with water to form new substances, these new substances dissolve in water, or these molecules directly fill the gaps between water molecules. These molecules, ions, etc. are solutes. In addition, some polar substances dissolve in water through hydrogen bonds with water molecules.

For most substances, the mass they can dissolve in water is limited. This limit is called solubility. Some substances can be miscible with water in any ratio, such as ethanol, but most substances no longer dissolve when they reach solubility. Precipitation will form or gas will be released. This phenomenon is called precipitation.

There is also a special state called colloid. In the colloid, the size of the particles is about 100 nm, and they are not precipitated due to the charge and are suspended in the solution. Milk is a common colloid.

Due to the different particle size and solubility of the dissolved substance (called solute), the transparency of the aqueous solution will be different. The solution will further form a precipitate at the bottom and become a precipitated colloidal solution.

Beside this there is:

Biological water: water in different states existing in various life systems

Natural water: Natural water constitutes the general term for various forms of water phases on the surface of the earth in nature. It includes surface water such as rivers, oceans, glaciers, lakes, swamps, and natural water bodies such as groundwater in soil and rock layers.

Soil water: water stored in soil

Groundwater: water stored underground

Ultra-pure water: extremely pure water, mostly used in the integrated circuit industry

Pure water: High purity water, considered non-conductive

Crystal water: also known as hydrated water. In a crystalline substance, a certain amount of water molecules are combined with ions or molecules by chemical bonding force.

The chemical formula of heavy water is D2O. Each heavy water molecule is composed of two deuterium atoms and one oxygen atom. Heavy water accounts for less than two ten thousandths of natural water, and the heavy water obtained by electrolyzing water is more expensive than gold. Heavy water can be used as a moderator and heat carrier for nuclear reactors.

The chemical formula of super heavy water is T2O. Each heavy water molecule is composed of two tritium atoms and one oxygen atom. Overweight water is extremely rare in natural water, and its proportion is less than one part per billion. The production cost of super heavy water is ten thousand times higher than that of heavy water.