Information about water

Water (H2O) is an inorganic substance composed of hydrogen and oxygen, and it is a colorless and odorless transparent liquid at normal temperature and pressure. In nature, pure water is very rare. Water is usually a solution of acid, alkali, salt and other substances, and is still customarily called water. Pure water can be obtained by several distillations with platinum or seasonal utensils. Of course, this is pure water in a relative sense, and it is impossible to be absolutely free of impurities. Water is a substance that can be converted between liquid, gas and solid. Solid water is called ice; The state of gas is called water vapor. When the temperature of steam is higher than 374.2℃, gaseous water cannot be converted into liquid water by pressurization.

At 20℃, the thermal conductivity of water is 0.006 J/s? cm？ K, the thermal conductivity of ice is 0.023 J/s? cm？ K, when the density of snow is 0. 1× 103 kg/m3, the thermal conductivity of snow is 0.00029 J/s? cm？ K at 3.98℃, the maximum density of water is1×10.3 kg/m3. When the temperature is higher than 3.98℃, the density of water decreases with the increase of temperature. At 0 ~ 3.98℃, water does not obey the law of thermal expansion and cold contraction, but its density increases with the increase of temperature. At 0℃, the density of water is 0.99987×10.3kg/m3 and the density of ice is 0.9167×10.3kg/m3. So ice can float on the water.

Water has strong thermal stability. When steam is heated above 2000K, only a small amount will be dissociated into hydrogen and oxygen, while distilled water will be dissociated into hydrogen and oxygen under the condition of direct current. It has great cohesion and surface tension. Except mercury, the surface tension of water is the largest, which can produce obvious capillary phenomenon and adsorption phenomenon. Pure water has no conductivity, while ordinary water contains a small amount of electrolyte and has conductivity.

Water itself is also a good solvent, and most inorganic compounds are soluble in water.

At -2 13. 16℃, water molecules will show hydrophobicity.

Physical properties:

Molar mass:18.05438+053g/mol.

Density: water 0.998g/cm3 (20 degrees), ice 0.92g/cm3.

Melting point: 0 degree 273. 15k

Boiling point: 100 degrees 373. 15K( 1 at standard atmospheric pressure)

Specific heat: 4. 184 joules/(g g)

water cycle

The biosphere can be divided into hydrosphere, atmosphere and lithosphere. Water circulates in the above areas as follows:

1. It can also evaporate from animals and plants and enter the air from the ocean or other water bodies;

2. Sink into the ocean from the sky and enter the ocean from land runoff;

3. Most of the water vapor evaporates from the ocean and returns to the ocean, but the wind blows the water vapor across the land and flows back to the ocean from the land runoff, which is about 36Tt per year. Water evaporates from land by 7 1Tt every year. There is 107Tt precipitation every year in the following forms: the most common are rainfall, hail, fog and dew. Concentrated water can reflect sunlight to form a rainbow.

Water in Chinese characters

(hieroglyphs. Oracle Bone Inscriptions glyph. The middle is like a water vein, and the sides are like running water. "Water" is the radical of Chinese characters. From the word water, it refers to the name of a river or water conservancy, or the direction of water flow, or the nature and state of water. Original meaning: The liquid falling from the clouds in the form of rain is colorless, odorless and transparent, forming rivers, lakes and oceans, and its molecular formula is H2O, which is the main component of all living things).

1. Same meaning [water]

Water, yes. -Shuo Wen

Water, yes. Yes, yes. The world is not equal to water. -"Explanation of name"

Cold accumulated in yin is water. -"Huainanzi"? astronomy

The five elements say water. -"book? Hong fan

Where water comes out of the plain, it is a flood. -"Zuo zhuan"? The first year of Huan gong

Water is pure and clean. -Book of Rites? Qu Li

Ice, water, but colder than water. -Xunzi? Persuasive learning

Liu Yuzhou's royal family has outstanding talents and is admired by all the people. Song? Sima Guang's "Zi Tong Zhi Jian"

Another example: water hammer (small appliance for boiling water); Shuitouer (storm); Moist water (moisture; Moisture); Halo (water sickness); Shuicheng (a small water tank next to the inkstone for storing and grinding ink); Water ebbs and flows (metaphor for inner stability); Spray peach blossoms with water (figuratively good-looking); Mr. Shui Jing (referring to Si Mahui in the Three Kingdoms, as clear as a mirror); Mixed land and water. Food and food are displayed together); Brief introduction of water (brief introduction of cities near water); Water vortex (vortex in water); Water pavilion (pavilion or post station by the water)

2. Especially rivers [rivers]

In Mae Shui. -"Poetry? Qin Feng? Jia Jian

She has been taking care of an empty boat in the estuary, with no companions except the bright moon and cold water. Don? Bai Juyi's Pipa Trip (Parallel Prose)

Another example: Shuikou (ferry); Water branch (tributary of a river); Shui Zhi (a book about water system); Water butterfly (refers to the literature describing water system); Shui Gu (Shanhegou); Water tail (the end of a river); Water rat (thief stealing a boat); Water (about river water conservancy); Water prohibition (river prohibition); Water sink (river interchange)

3. Generally refers to all waters [waters]

The water house is deep, I am ignorant, and the master is not far away. What would he do? Don? Li "Liu Yichuan"

Liu Bei and Zhou Yu go hand in hand. Song? Sima Guang's "Zi Tong Zhi Jian"

Another example: land and water (the land and water Dojo in Buddhism); Shui Bo (Hu Ze); Shuiju (living in a water town); Water shovel (ditch); Water king (another name for the sea); Water Bo (the legendary water god; River); Water hotel (spend the night on the water; Accommodation in water); Water veins (waterways, underground undercurrents); Poor water (due to too much rain, water accumulates in the field or flows to the ground)

4. Fruit juice and liquid [liquid].

Such as: water ceremony (fruit bait and other gifts); Fruit candy (candy made of fruit juice); Ink; Saliva; Tears; Potions; soda

5. floods; flood

Therefore, there were nine years of water and seven years of drought in Tang Dynasty. Han? Chao Cuo's On Your Millet

Yue: Is there a law in heaven and earth? Yue: Floods, droughts and epidemics are also ways to regulate heaven and earth. -Green? Hong's "Zhi Ping Pian"

Another example: water storage (facilities to prevent floods); Water dike (flood wall)

5. Star name [Morning Star].

Such as: stachys (constellation name. Ancient astronomers collectively referred to Polaris and the Seven Nights)

6. Official name [official name].

Such as: Shuiyu (ancient official name. Act in charge of Kawasawa); Water conservancy official (official in charge of water resources management and fishery tax)

7. Silver content in currency. The fineness of silver is converted into the name of currency exchange subsidy and remittance fee [silver content in coins].

Such as: discount; Detain water; Collecting water; Water silk (secondary silver)

8. One of the five elements [water, one of the five elements]

Five elements: water, fire, wood, gold and earth. -"book? Hong fan

9. Aquatic animals and plants.

For example, I can't afford to grow water in the field, and the lake has recently collected rent.

10. Always refers to the painful life situation of nuns and prostitutes [deep distress].

Such as: water affairs bureau (formerly referring to prostitutes in brothels); Water passengers (dock vendors, also known as traffickers)

1 1. Extra income or extra expenses.

"Making money" means "[extra income]".

12. refers to the water army [troops fighting on water]

When all the people saw the book that the water level was 800 thousand, they were frightened. Song? Sima Guang's "Zi Tong Zhi Jian"

13. [Aquarium] A minority in China lives in Guizhou Province.

14. Last name

15. Five strokes are divided into two.

The source of water

The earth is the only planet covered with liquid water among the eight planets in the solar system. There are great differences in academic circles about the origin of water on the earth, and there are dozens of different theories of water formation at present. Some people think that in the early days of the earth's formation, hydrogen in the primitive atmosphere was oxidized into water, and water vapor gradually condensed to form the ocean; There is also a view that water originally existed in the nebula material that formed the earth. Another view is that silicate and other substances in the original crust react under the influence of volcanoes and precipitate water. There are also views that comets and meteorites attracted by the earth are the main sources of water on the earth, and even now the water on the earth is still increasing.

Impact on climate

Water can regulate the climate. Water vapor in the atmosphere can block 60% of the earth's radiation and protect the earth from being cooled. Ocean and land water bodies can absorb and accumulate heat in summer, so that the temperature will not be too high; Heat can be released slowly in winter, so that the temperature will not be too low.

Water on the surface of the ocean and the earth evaporates into the sky to form clouds. Water in the clouds falls into the rain through precipitation and turns into snow in winter. Water falling to the surface seeps into the ground to form groundwater; Groundwater gushes out from the stratum again, forming spring water, which flows into the sea through streams and rivers. Form a water cycle.

Precipitation activities such as rain and snow have an important influence on climate formation. In temperate monsoon climate, monsoon brings abundant moisture, forming obvious dry and wet seasons.

In addition, in nature, due to different climatic conditions, water will appear in the form of hail, fog, dew and frost, which will affect the climate and human activities.

Impact on geography

0% of the earth's surface is covered with water. Seen from the sky, the earth is a blue planet. Water erodes rock and soil, scours and silts rivers, transports sediments, builds plains and changes the surface morphology.

The surface water of the earth constitutes the hydrosphere, including oceans, rivers, lakes, swamps, glaciers, snow, groundwater and water in the atmosphere. Because the water injected into the ocean contains a certain amount of salt, and it accumulates and evaporates all the year round, the sea and ocean water are salty and cannot be directly drunk. The water in some lakes is also salty. The largest body of water in the world is the Pacific Ocean. The Great Lakes of North America are the largest fresh water system. The Caspian Sea on Eurasia is the largest saltwater lake.

The volume of water on the earth is about10.36 billion cubic kilometers, of which

Ocean accounts for1320,000,000 cubic kilometers (or 97.2%).

Glaciers and ice sheets account for 25 million cubic kilometers (or 1.8%).

Groundwater accounts for13 million cubic kilometers (or 0.9%).

Freshwater in lakes, inland seas and rivers accounts for 250,000 cubic kilometers (or 0.02%).

Water vapor in the atmosphere accounts for 13 000 cubic kilometers (or 0.05438+0%) at any given time.

Influence on life

Life on earth first appeared in water. Water is an important part of all living things. Water in the human body accounts for 70%; Jellyfish is 98% water. A large number of aquatic plants and other aquatic organisms live in the water.

Water is beneficial to chemical reactions in the body and also plays the role of transporting substances in the living body. Water plays an important role in maintaining the stability of biological body temperature.

Types of water

Different disciplines have different names for water:

According to the different water quality, it can be divided into:

Soft water: Water with hardness below 8 degrees is soft water. (No or only a few calcium and magnesium compounds)

Hard water: water with hardness higher than 8 degrees is hard water. (containing more calcium and magnesium compounds). Hard water will affect the effect of detergent; The high hardness of boiler water is very dangerous, which not only wastes fuel, but also causes local overheating of the pipeline in the boiler, which is easy to cause deformation or damage of the pipeline. People's long-term reference is harmful to health. There will be more scale when heated with hard water.

According to the content of sodium chloride, drinking water can be divided into:

fresh water

salt water

In addition, there are: biological water: water in different States existing in various living systems.

Natural water:

Soil water: Water stored in soil.

Groundwater: Water stored underground.

Ultra-pure water: water with high purity, mostly used in integrated circuit industry.

Crystal water: also known as hydrated water. In crystalline matter, a certain number of water molecules are bound to ions or molecules through chemical bonds.

The chemical formula of heavy water is D2O, and each heavy water molecule consists 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 electrolysis is more expensive than gold. Heavy water can be used as moderator and heat carrier for atomic reactors.

The chemical molecular formula of super heavy water is T2O, and each heavy water molecule consists of two tritium atoms and one oxygen atom. Ultra-heavy water is extremely rare in natural water, and its proportion is less than one billion. The production cost of ultra-heavy water is tens of thousands of times higher than that of water.

The chemical formula of deuterated water is HDO, and each molecule contains one hydrogen atom, one deuterium atom and one oxygen atom. Not very useful.

In addition, water also includes sweat, salt water, urine, distilled water, etc.