Water is a chemical substance In chemistry, a chemical substance is a material with a specific chemical composition with the chemical formula A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound H2O. Its molecule contains one oxygen Oxygen (pronounced /ˈɒksɨdʒɨn/, OK-si-jin, from the Greek roots ὀξύς (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter), is the element with atomic number 8 and represented by the symbol O. It is a member of the chalcogen group on the periodic table, and is a highly and two hydrogen Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of 1.00794 u (1.007825 u for Hydrogen-1), hydrogen is the lightest and most abundant chemical element, constituting roughly 75 % of the Universe's elemental mass. Stars in the main sequence are mainly composed of hydrogen in its atoms connected by covalent A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms, and other covalent bonds. In short, the attraction-to-repulsion stability that forms between atoms when they share electrons is known as covalent bonding bonds. Water is a liquid Liquid is one of the three classical states of matter. Like a gas, a liquid is able to flow and take the shape of a container, but, like a solid, it resists compression. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly constant density. A distinctive property of the liquid state is surface tension, at ambient conditions In chemistry, standard conditions for temperature and pressure are standard sets of conditions for experimental measurements, to allow comparisons to be made between different sets of data. The most used standards are those of the International Union of Pure and Applied Chemistry (IUPAC) and the National Institute of Standards and Technology (NIST), but it often co-exists on Earth with its solid Solid is one of the major states of matter. It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a gas does. The atoms in a solid are tightly bound to each other, state, ice Ice, technically, may be any one of the 15 known crystalline phases of water. In non-scientific contexts, the term usually means the phase known as ice Ih, which is the most abundant of these solid phases on the earth's surface. It can appear transparent or opaque bluish-white colour, depending on the presence of impurities or air inclusions. The, and gaseous Gas is one of four classical states of matter. Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons are so energized that they leave their parent atoms state, water vapor Water vapor or water vapour , also aqueous vapor, is the gas phase of water. Water vapor is one state of water within the hydrosphere. Water vapor can be produced from the evaporation of boiling liquid water or from the sublimation of ice. Under typical atmospheric conditions, water vapor is continuously generated by evaporation and removed by or steam Steam is either mist , or the gas phase of water (water vapor).
Water covers 70.9% of the Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the World, the Blue Planet,[note 6] or by its Latin name, Terra.[note 7]'s surface,[1] and is vital for all known forms of life Life is a characteristic that distinguishes objects that have signaling and self-sustaining processes (biology) from those that do not, either because such functions have ceased (death), or else because they lack such functions and are classified as inanimate.[2] On Earth, it is found mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers An aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard, which is a bed of low permeability along an aquifer, and and 0.001% in the air An atmosphere is a layer of gases that may surround a material body of sufficient mass,and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low. Some planets consist mainly of various gases, but only their outer layer is their as vapor A vapor or vapour (see spelling differences) is a substance in the gas phase at a temperature lower than its critical temperature. This means that the vapor can be condensed to a liquid or to a solid by increasing its pressure without reducing the temperature, clouds A cloud is a visible mass of droplets of water or frozen crystals suspended in the atmosphere above the surface of the Earth or another planetary body. A cloud is also a visible mass attracted by gravity, such as masses of material in space called interstellar clouds and nebulae. Clouds are studied in the nephology or cloud physics branch of (formed of solid and liquid water particles suspended in air), and precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that is pulled down by gravity and deposited on the Earth's surface. The main forms of precipitation include rain, snow, ice pellets, and graupel. It occurs when the atmosphere, a large gaseous solution, becomes saturated with water vapour and the water.[3] Oceans An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface (~3.61 X 1014 m2) is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas hold 97% of surface water, glaciers A glacier is a perennial mass of ice which moves over land. A glacier forms in locations where the mass accumulation of snow and ice exceeds ablation over many years. The word glacier comes from French via the Vulgar Latin glacia, and ultimately from Latin glacies meaning ice. The corresponding area of study is called glaciology and polar ice caps An ice cap is an ice mass that covers less than 50 000 km² of land area . Masses of ice covering more than 50 000 km² are termed an ice sheet 2.4%, and other land surface water such as rivers A river is a natural watercourse, usually freshwater, flowing toward an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including stream, creek, brook, rivulet, and rill; there is no, lakes A lake is a terrain feature , a body of liquid on the surface of a world that is localized to the bottom of basin (another type of landform or terrain feature; that is not global). Another definition is a body of fresh or salt water of considerable size that is surrounded by land. On Earth a body of water is considered a lake when it is inland, and ponds A pond is a body of standing water, either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens designed for aesthetic ornamentation, fish ponds designed for commercial fish breeding, and solar ponds designed to store thermal energy 0.6%. A very small amount of the Earth's water is contained within biological bodies and manufactured products.
Water on Earth moves continually through a cycle The water cycle, also known as the hydrologic cycle or H2O cycle, describes the continuous movement of water on, above and below the surface of the Earth. Water can change states among liquid, vapour, and ice at various places in the water cycle. Although the balance of water on Earth remains fairly constant over time, individual water molecules of evaporation Evaporation is a type of vaporization of a liquid, that occurs only on the surface of a liquid. The other type of vaporization is boiling, that instead occurs on the entire mass of the liquid. Evaporation is also part of the water cycle or transpiration Transpiration is a process similar to evaporation. It is the loss of water vapor from parts of plants , especially in leaves but also in stems, flowers and roots. Leaf surfaces are dotted with openings called, collectively, stomata, and in most plants they are more numerous on the undersides of the foliage. The stoma are bordered by guard cells (evapotranspiration Evapotranspiration is a term used to describe the sum of evaporation and plant transpiration from the Earth's land surface to atmosphere. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, and waterbodies. Transpiration accounts for the movement of water within a plant and the subsequent), precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that is pulled down by gravity and deposited on the Earth's surface. The main forms of precipitation include rain, snow, ice pellets, and graupel. It occurs when the atmosphere, a large gaseous solution, becomes saturated with water vapour and the water, and runoff Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, snowmelt, or other sources flows over the land. This is a major component of the hydrologic cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source. If a nonpoint source contains man-made, usually reaching the sea A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, the term refers to a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean. It is also used sometimes to describe a large saline lake that lacks a natural outlet, such as the Caspian Sea. Over land, evaporation and transpiration contribute to the precipitation over land.
Clean drinking water Drinking water or potable water is water of sufficiently high quality that it can be consumed or used without risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually consumed or used in food is essential to human Humans, known taxonomically as Homo sapiens , are the only living species in the Homo genus of bipedal primates in Hominidae, the great ape family. However, in some cases "human" is used to refer to any member of the genus Homo and other lifeforms. Access to safe drinking water has improved steadily and substantially over the last decades in almost every part of the world.[4][5] There is a clear correlation between access to safe water and GDP The gross domestic product or gross domestic income (GDI) is a measure of a country's overall economic output. It is the market value of all final goods and services made within the borders of a country in a year. It is often positively correlated with the standard of living, though its use as a stand-in for measuring the standard of living has per capita.[6] However, some observers have estimated that by 2025 more than half of the world population The world population is the population of humans on the planet Earth. It is currently estimated to be 6,866,400,000 by the United States Census Bureau. In 2009, the United Nations predicted that the population would reach 7,000,000,000 in 2011 will be facing water-based vulnerability.[7] A recent report (November 2009) suggests that by 2030, in some developing regions of the world, water demand will exceed supply by 50%.[8] Water plays an important role in the world economy The world economy can be evaluated in various kind of ways: depending on the model used, and this valuation can then be represented in various ways . It is inseparable from the geography and ecology of Earth, and is therefore somewhat of a misnomer, since, while definitions and representations of the "world economy" vary widely, they, as it functions as a solvent A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature. Common uses for organic solvents are in dry cleaning (e.g. tetrachloroethylene), as a paint thinner (e.g. toluene, turpentine), as nail polish removers and for a wide variety of chemical substances and facilitates industrial cooling and transportation. Approximately 70% of freshwater Freshwater or fresh water is naturally occurring water on the Earth's surface in bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Freshwater is characterized by having low concentrations of dissolved salts and other total dissolved solids. The term specifically excludes seawater and is consumed by agriculture Agriculture is the production of food and goods through farming. Agriculture was the key development that led to the rise of human civilization, with the husbandry of domesticated animals and plants creating food surpluses that enabled the development of more densely populated and stratified societies. The study of agriculture is known as.[9]
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Wed, 01 Sep 2010 14:02:04 GMT+00:00
MarketWatch (press release) This award, Insituform's largest single project with the Macon Water Authority, includes 9500 feet of 54-inch pipelines located in Central City Park, ...
