by Lime Red Tetrahedron

Created on: February 19, 2009   Last Updated: March 03, 2009

Water, although exhibiting a simple chemical structure, demonstrates astounding properties that have time and time again challenged our chemical theories. These properties are those that make this vital substance necessary for life. Unlike similar compounds which are gasses at room temperature, water exists as a liquid. It acts as an effective insulator, and can be used as a cooling agent in organic systems. Water is often called the "universal solvent" because of its ability to dissolve polar substances. This liquid also has the remarkable properties of cohesion and adhesion, leading to the phenomenon of capillary action. Of course, the natural question that scientists asked after said phenomena were observed was: why? The believed causes and effects of the properties of water will be explored in this article.

Thermal Properties of Water The thermal properties of water are essential for life. Perhaps the most fundamental thermal property of water to life is its large specific heat capacity (4.19J/(gC)). The water molecule has many degrees of freedom, allowing water to absorb a very large amount of thermal energy with only a small increase in temperature. This property contributes to the stability of organisms that contain water, as the specific heat capacity decreases the fluctuations in the organism's temperature, allowing fundamental chemical reactions to proceed more reliably. Water's high heat of vaporization and low heat of fusion allow water to exist as a liquid within the temperature range in which essential chemical reactions can occur. The high heat of vaporization and low heat of fusion are due to the nature of the water molecule. Unlike similar hydrogen compounds which exist as gasses at room temperature (such as H2S), water molecules have the ability to hydrogen-bond to each other, a property due to the high electronegativity of the oxygen atom. The hydrogen nucleus is left more exposed, allowing it to form a strong positive pole which attracts the negatively-charged oxygen atoms of other molecules. As the molecules of water bond strongly to one another, and because of the high specific heat capacity of water (many internal degrees of freedom), the energy required to overcome the attraction between the water molecules is very large, causing the heat of vaporization to be high. As water molecules can store large amounts of thermal energy, much thermal energy must be removed before the molecules form a solid, resulting in a low heat of fusion. The

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