|Systematic name||Systematic name::Water|
|Molecular formula||Simple formula::H₂O|
|Molar mass||Molar mass::18.0153 g/mol|
|Melting point||Melting point::0 °C|
|Boiling point||Boiling point::100 °C|
|Triple point||Triple point::0.01 °C|
|CAS number||CAS number::7732-18-5|
| Except where noted otherwise, data are given for|
materials in their standard state (at 25 °C, 100 kPa)
Water, or aqua, or dihydrogen monoxide, or hydrogen hydroxide, is an essential molecule. All life on earth depends on water to survive and function properly. Plants need water to properly perform photosynthesis. Humans and animals need water to stay hydrated and for cellular respiration to work.
Water is the most distinguishing characteristic of the earth, another wonder of God’s work. Water covers 71 % of the earth’s surface. Most of this is saltwater and is found in the world’s oceans, although a fair portion is contained in glaciers, water molecules in the air, streams, rivers, lakes and the polar caps.
A surprising amount of water is found elsewhere in the solar system. This finding has given rise to much speculation on the existence of life on other celestial bodies.
Water is a pure substance composed of three atoms, two of comprises::hydrogen and one of comprises::oxygen. The atoms are joined with covalent bonds. It is odorless, tasteless, colorless, transparent, and liquid at room temperature. When water cools to or below 0° Celsius, it freezes. At that point water becomes a solid and gains a cloudy white hue. When water reaches 100° Celsius or higher, it begins to boil, at which it retains the same properties of water at room temperature.
Water is the most common solvent of inorganic compounds. It dissolves almost any other inorganic substance, including salts, sugars, acids, alkalis, and some gases. It dissolves some organic compounds also, and specifically the polar compounds.
Cohesion and Adhesion
Because water is polar, it tends naturally to stick to other water molecules, a phenomenon called cohesion. Thus when water is splashed on a smooth surface, it tends to form small clumps. The arrangement of the electrons give it a partial negative charge next to the oxygen atom and a partial positive charge near the two hydrogen atoms. Oxygen has higher electronegativity than does hydrogen, and hence pulls the electrons toward it.
Because of these properties it also adheres to other elements. Water also has surface tension. Since the water molecules are cohesive, any object on the top of a body of water will experience a force exerting itself against it.
Ice is uniquely less dense than water, which is unusual because every other solid is denser than its liquid form. Furthermore, when water freezes, it solidifies from top to bottom, while the bottom remains at a constant temperature of 4 degrees Celsius.
Most people assume that water is a good conductor of electricity on account of the obvious risk of electrocution. This is not actually true. Water does self-ionize, and this is why water can conduct electricity at all. But water is not conductive enough to be considered a good conductor.
Water on the Earth
More than two thirds of the surface of the earth is covered by water. 97.2 percent of this water is in the world's four oceans: the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, and the Arctic Ocean, plus the waters surrounding the continent of Antarctica. The water in these oceans is all saltwater. The other 2.8 percent is in lakes, rivers and streams on the continents; all of this is fresh water. Of the 2.8 percent freshwater in the world, 90 percent is in the Antarctic ice sheet.
Occurrencesatmosphere and eventually becomes clouds. These newly formed clouds become dense and filled with water vapor, which precipitates as rain, snow, or other forms. This precipitation pours back the water into the rivers, seas, lakes, and the cycle begins again.
Some forms of water are found more commonly than others, and some places do not have certain forms of water. For example on the north and south poles, glaciers, seawater, hail, and snow are all very common, but rain is almost never found there on account of the atmospheric conditions. In most countries, the most common forms of water include snow, rain, rivers, lakes, streams, and clouds.
In addition to surface water, ground water exists in significant amounts under most of the world's land surface. This fresh water is contained in aquifers within rock layers often deemed to be millions of years old according to traditional geology. Often accessed through wells, ground water supplies fresh water to many for whom water from surface water resources is unavailable. Ground water is evidence of the gracious gifts of the Creator to Planet Earth. If ground water was a remnant of ancient oceans, then it could be expected to be salt water rather than fresh water.An interesting form of water found commonly everywhere is a rainbow, which is suspended water molecules refracting the sunlight and acting as a prism. The Bible mentions the rainbow as a symbol of God's promise never again to drown the earth in a repeat of the global flood.
And God said, "This is the sign of the covenant I am making between me and you and every living creature with you, a covenant for all generations to come: I have set my rainbow in the clouds, and it will be the sign of the covenant between me and the earth. Whenever I bring clouds over the earth and the rainbow appears in the clouds, I will remember my covenant between me and you and all living creatures of every kind. Never again will the waters become a flood to destroy all life. Whenever the rainbow appears in the clouds, I will see it and remember the everlasting covenant between God and all living creatures of every kind on the earth." Genesis 9:12-16
Because water is such a common solvent, it dissolves many different elements and minerals, which can give it a distinct color, taste or odor depending on what it holds in solution. This can also affect its effect on life. For example, when water dissolves salt, as found in the ocean, it becomes unhealthy for animals and people, and even dehydrates life more. However, depending on what the water dissolves, it can also be more healthful. Water from mountain springs often contains many dissolved minerals and vitamins and other health-promoting nutrients.
Water has many, many different properties that are not only unique, but also make it essential to life. All known life needs water to survive. Water is the key factor in the process of metabolism. Also it is vital in photosynthesis and respiration. In photosynthesis, plants use the sun's solar energy to split the hydrogen and oxygen atoms in water to form glucose for food and release oxygen. Living cells need water for respiration, in which the sun's energy is used to reform water from oxygen and hydrogen atoms.
Water is essential to both the human body, and our civilization. We need it for our bodies to work and be in shape, and to run and power many different areas of technology.
Water constitutes 70 percent of the human body. Everyday the body needs several liters to function properly and to work efficiently, depending on the exercise and amount of work the person is doing. During the day you gain water through the foods you eat, so that you need not drink multiple liters of straight water.
Industrial and Recreational Uses
Hydroelectric dams use water's flowing power to create motion to produce electricity. This method of producing electricity is widely noted for its efficiency and safety for the environment. Water is also used under high pressure in many machines and utensils to make very precise cuts in materials like rock or marble. The high specific heat of water makes it useful as a coolant.
Humans also use water for recreation. Fishing, swimming, surfing, water skiing, and boating are all very popular pastimes.
Animals use water as humans do, for hydration and respiration and many other functions. In addition some animals live in the water. Nearly all kinds of fish live in the water, with very few exceptions. Many mammals, like dolphins and other great whales, live in the water also. The amphibians live part of their lives under water and the rest on land. Frogs, toads, and newts are all amphibians.
These animals all have different ways of obtaining oxygen from the water they live in. Fish primarily have gills for gleaning oxygen from the water all around them. Some animals have both gills and lungs. All mammals that live in the ocean have lungs and must surface to the air to breathe.
- Water by Wikipedia
- Water Brittanica
- Water Properties by Marcy M. Seavy
- What is the Water Cycle? by Howard Perlman
- Water Properties and Behavior by Anthony Carpi