Importance of water

Water is the medium of life an is the most important compound in all organisms. It varies from 65 to 89% in different organisms.

Water is vital for human survival. The human body is made up of about 60% water, and it is required for numerous physiological functions such as digestion, metabolism, circulation, temperature regulation, and waste elimination. Without water, human beings cannot survive.

Adequate water intake is crucial for maintaining proper hydration levels in the body. Dehydration can lead to a range of health issues, including fatigue, dizziness, headaches, and even life-threatening conditions such as heatstroke.

Important properties of water

Solvent properties:

Nonpolar substances are dispersed in water. All chemical reactions in cell occur in aqueous media.

Water is often called the “universal solvent” because it has the ability to dissolve a wide range of substances. 

Due to its polar nature, with oxygen being slightly negative and hydrogen being slightly positive, water molecules can surround and solvate ions and polar molecules. 

This allows water to dissolve a wide variety of substances, including salts, sugars, acids, and many biological molecules such as proteins and nucleic acids.

Water has a high dissolving capacity, meaning it can dissolve a large amount of solute compared to its own mass. 

This is due to its strong hydrogen bonding, which allows it to break apart ionic and polar compounds into individual ions or molecules and disperse them uniformly throughout the solution.

When a substance dissolves in water, it is surrounded by water molecules through a process called hydration. The water molecules form a shell around the solute particles, stabilizing them and preventing them from re-aggregating or precipitating out of the solution. 

This makes water an excellent medium for chemical reactions to occur, as reactants can come into close contact and interact with each other.

Heat capacity:

Water has a great ability of absorbing heat with minimum of change in its own temperature. The specific heat capacity of water, for example the number of calories of heat required to rise the temperature of 1 g of water by 1°C is 1.0. 

This means more heat is required to raise the temperature of water by 1°C, this is because much of the energy is used to break hydrogen bonds and water. 

Water thus act as temperatures stabiliser for organisms in the environment and hence protects living material against sudden thermal changes.

Water’s high heat capacity is due to its hydrogen bonding. Hydrogen bonds are relatively strong intermolecular forces that form between the positively charged hydrogen atoms of one water molecule and the negatively charged oxygen atoms of neighbouring water molecules. 

These hydrogen bonds require energy to break, which leads to a higher heat capacity compared to substances with weaker intermolecular forces.

Heat of vaporization:

Water absorb much of it as it changes from liquid to gaseous state. For example, it provides cooling effect to plants when water is transpired and to animals when water is respired.

The high heat of vaporization of water has several important implications. One of the most significant is its role in evaporative cooling. 

When water evaporates from a surface, such as during sweating in humans or during transpiration in plants, it absorbs heat energy from the surroundings to overcome the attractive forces between water molecules and transition from the liquid phase to the vapour phase. 

This results in a cooling effect on the surface from which the water is evaporating, which is important for regulating temperature in living organisms and for many industrial processes that rely on evaporative cooling, such as air conditioning and refrigeration.

Ionization of water:

Water molecules ionized into H+ an OH- ions which affect and take part in many of reactions that occur in cells.

Water’s ability to self-ionize is due to its amphoteric nature, which means it can act as both an acid and a base. Water molecules can donate a hydrogen ion (H+) to form a hydroxide ion (OH-) and can also accept a hydrogen ion (H+) to form a hydronium ion (H3O+). 

The equilibrium between water, hydrogen ions, hydroxide ions, and hydronium ions is maintained in a constant state of dynamic equilibrium in pure water.

Protection:

Water act as lubricant that provides protection. For example, tears protect the surface of eyes from rubbing of eyelids. Water also forms a flute cushion around organs that helps to protect them from trauma (injury).

Water is a major component of cells and serves as a protective medium for cellular structures and organelles. It helps to maintain the integrity and shape of cells by providing a medium for biochemical reactions to occur and by serving as a barrier against harmful substances.

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