Biological significance of water Essay Example | Topics and Well Written Essays - 1000 words

Biological significance of water - Essay Example Water is found on the earth in three forms: solid, liquid and gas; or ice, liquid water and gas respectively. It is essential for all living things and it is often referred to as a universal solvent because many substances dissolve in it. These unique properties of water result from the ways in which individual H2O molecules interact with each other.Water is the chemical substance with chemical formula H2O: one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom. Oxygen attracts electrons much more strongly than hydrogen, resulting in a net positive charge on the hydrogen atoms, and a net negative charge on the oxygen atom. The presence of a charge on each of these atoms gives each water molecule a net dipole moment. Electrical attraction between water molecules due to this dipole pulls individual molecules closer together, making it more difficult to separate the molecules and therefore raising the boiling point. This attraction is known as hydrogen bo nding. Water can be described as a polar liquid that dissociates disproportionately into the hydronium ion (H3O+(aq)) and an associated hydroxide ion (OH(aq)). Water is in dynamic equilibrium between the liquid, gas and solid states at standard temperature and pressure, and is the only pure substance found naturally on Earth to be so. Water's has a melting point of zero degrees and boiling point of 100 degrees Celsius respectively. These properties are higher than would be expected based on similar compounds. Thus, water remains a liquid under a higher range of temperature compared to other compounds. As a result, plants and animals do not start freezing at lower temperatures or boiling at higher temperatures. Viscosity Because of its comparatively smaller molecular weight, it is unusually viscous. Water has the ability to act as either an acid or a base depending on the circumstances, and by its nature it is perfectly neutral (it's the standard for balance between acids and alkalines [bases]). Universal Solvent Water is the most universal of solvents and though polar in its make up, it exhibits properties that indicate a sort of polymerizing link between its molecules similar to heavier organic non-polar compounds. Existence in three forms: solid, liquid, gas It exists on earth in all three basic states, solid, liquid, and gas, High Heat capacity Water is also extremely useful due to its high heat capacity. It has an enormous ability to absorb and transmit energy. For example the amount of energy it would take to melt 1 kilogram of ice at zero degrees Celius would be enough to lower the temperature of 1 kilogram of Aluminum over 570 degrees Celsius. While the amount of heat it would take to melt that kilogram of ice, heat it and boil away, 720 Calories, would be enough to raise that same amount of Aluminum to its melting point! This is why water is ideal as a insulation or a heat dissipation source. It holds more heat than just about anything. Easily reacts with other compounds Water reacts with more substances than any other compound. It reacts physically with several compounds to add to their crystal structure. Compounds like copper and magnesium sulfate are two examples of many compounds that almost always found in nature with water molecules physically attached to their crystal structure. These type of compounds are often "dried out" or dehydrated and used to absorb water from their surroundings. Some of these compounds, have water as such an important part of their structure that they will even extract all available moisture from the air. These compound are natural dehumidifiers, dependent on water to complete their structure.