- 1) Water – The Life-Giving Fluid
- 2) Molecular Formula
- 3) Water on Earth
- 4) Properties of Water
- 5) Importance of Water
- 6) Solvent properties
- 7) Specific Heat Capacity
- 8) Heat of vaporization
- 9) Ionization of water
- 10) Protection
- 11) Uses of Water
Water – The Life-Giving Fluid
Water is an inorganic, transparent, tasteless, odor-free, and nearly colourless chemical substance, which is the primary constituent of Earth’s hydrosphere and the fluids of all living organisms.
Water on Earth
The oceans contain about 97% of Earth’s water. The remaining of the water is in the form of glaciers, ice caps, groundwater and inland water (rivers, lakes, streams). It is likewise present in the atmosphere in the form of water vapours. Seawater is unsuited for drinking and farming purposes due to high portion of dissolved salts.
Only 0.2% of the overall water on the Earth is safe and clean, i.e. fit for drinking purposes.
Properties of Water
Water is made up of two components: oxygen and hydrogen. One atom of oxygen combines with two atoms of hydrogen to form one molecule of water. Distilled water is a clear, colourless, odourless and tasteless liquid with the following properties:
- It is neutral to litmus.
- Its freezing point is 0 ° C and the boiling point is 100 ° C at sea level.
- Its optimum density is 1 g cm-3 at 4 °C.
- It is an outstanding solvent for ionic in addition to molecular substances.
- It has an abnormally high heat capacity of about 4.2 Jg-1K-1, which is about six times greater than that of land. This specific property of water is responsible for keeping the Earth’s temperature level within limits. Otherwise, day time temperature would have been extremely high to bear and night time temperature level would have been too low to freeze everything.
- It has high surface area tension. This distinct property of water is accountable for its high capillary action. Capillary action is the procedure by which water rises up from the roots of plants to leaves. This procedure is important for the survival of the land plants.
Importance of Water
Water is the medium of life. It is the most plentiful substance in all organisms. It varies from 65 to 89 per cent in different organisms. Human tissues consist of about 20 per cent of water in bone cells and 85% in brain cells. Almost all actions of a cell take place in the existence of water. It likewise participates in numerous biochemical reactions such as hydrolysis of macromolecules. It is also used as a raw material in photosynthesis.
Due to its polarity, water is an excellent solvent for polar substances. Ionic compounds when dissolved in water, dissociate into positive and negative ions. Non-ionic substances having charged groups in their molecules are distributed in the water.
When in solution, ions and molecules move arbitrarily and are in a more favourable state to react with other particles and ions. It is because of this characteristic of water that almost all reactions in cells occur in liquid media.
In cells, all chemical reactions are catalyzed by enzymes which operate in a liquid environment. Nonpolar natural particles, such as fats, are insoluble in water and help to keep membranes which make compartments in the cell.
Specific Heat Capacity
Water has the ability to take in the heat with a minimum of change in its own temperature level. The specific heat capacity of water – the number of calories required to raise the temperature of 1g of water from 15 to 16 ° C is 1.0. This is because much of the energy is used to break hydrogen bonds. Water hence works as temperature level stabilizer for organisms in the environment and hence secures living organisms against unexpected thermal changes.
Heat of vaporization
Water takes in much heat as it alters from liquid to gas. The heat of vaporization is expressed as calories taken in per gram vaporized. The specific heat of vaporization of water is 574 Kcal/kg, which plays an important function in the maintenance of heat produced by oxidation.
It likewise offers a cooling effect to plants when water is transpired, or to animals when water is perspired. Evaporation of just two ml out of one litre of water lowers the temperature of the remaining 998 ml by 1 ° C.
Ionization of water
The water moleculeionizes to form H+ and OH– ions:
This reaction is reversible however a balance is preserved. At 25 ° C, the concentration of each of H+ and OH- ions in distilled water is 10-7 mole/litre. The H+ and OH– ions affect, and take part in a number of the reactions that take place in cells.
Water is an effective lubricant that provides safety against damage arising from friction. For instance, tears protect the surface of the eye from the rubbing of eyelids, water likewise forms a fluid cushion around organs that assists to protect them from trauma.
Uses of Water
Water is stored in numerous parts of the world however not evenly distributed all over the earth. It is a universal solvent. Different sources of water are– sea, lake, rain, well, stream, borehole and pond. It is used for washing, drinking, generating electrical energy and so on. Here are the various uses of water.
Domestic uses of water
15 % of water is consumed for domestic purpose. Water is utilized for drinking, bathing, cooking food and cleaning utensils, clothes, fruits, veggies and brushing teeth.
Water usage for farming
Agriculture is the largest consumer of water. About 70% of water is used for irrigation. Water is essential for gardening, farming and fisheries. Plants need water to grow. Throughout the procedure of photosynthesis, they take in water. To yield crops, fruits, flowers, veggies they require adequate water, manure and oxygen.
Industrial uses of water
Industrial water is used for cleaning, cooling, processing, transferring, diluting or fabricating of a product. The maximum quantity of water is utilized in the production of chemical, paper and food.
Other uses are– it is utilized in transportation, manufacturing, hydroelectric power, elimination of body wastes.