Water covers two-third's of the earth's surface. It is essential for the biochemical reactions that enable life. Four properties of water that make it an ideal medium for these biochemical reactions are its abilities as a solvent, the way it facilitates chemical reactions, and its high specific heat and its neutral pH.

 

 

Water is a solvent:

 

A molecule of water is composed of two hydrogen atoms and one oxygen atom. The oxygen atom attracts more of the molecule's electrons toward it, giving it a negative charge. The pull of the electrons away from the two hydrogen atoms, leave the hydrogen side of the molecule with a partial positive charge. This dipole structure is what makes water an effective solvent for polar substances. Non-polar substances, such as lipids and other fatty acids, will not dissolve in water. This is called a hydrophobic effect and is important for the formation of cell membranes.

 

 

Facilitates chemical reactions:

 

The dipole nature of the water molecule also allows it to facilitate chemical reactions. Certain molecules need to be bent in specific ways in order for reactions to occur. The way that the electrical charges are arranged on the water molecule can alter the shape of other molecules, allowing them to bend into the shapes needed for biochemical reactions to occur.

 

 

High Specific Heat: 

 

The specific heat of a substance is the amount of heat that can be absorbed before the substance begins to change temperature. Water has a high specific heat, which makes it a good medium for chemical reactions to occur, as it can absorb the energy created by those reactions without getting hot. Water also releases heat energy slowly, making it a good buffer for living organisms that need to regulate their temperature.

 

 

Neutral pH :

 

pH is a measure of how acidic or alkaline a substance is. It is measured on a scale of 0 to 14. Water naturally has a neutral pH, and is assigned a pH value of 7. Human blood, being mostly water, has a natural pH of 7.4. Living tissues can be damaged by either extreme of acidic or containing high amounts of alkaline substances, as such, water's neutral pH is a healthy environment for the biochemical reactions necessary for life.

 

Water plays a critical role in life since in just about every biochemical reaction that takes place in a living organism depends on it to produce all the necessary ingredients to sustain it.There is no other substance or molecule in the universe capable of interacting with as many of the elements in the periodic table as water to produce hundreds or even thousands of chemicals for life to exist.