AGRICULTURE AND CHEMISTRY

• Agriculture is another field where revolutionary changes have come about through the growth of chemistry.  When world population increased rapidly, the need for food materials also increased. It was impossible to cater to this increased need through traditional ways of agriculture. Through modern methods of farming, food production multiplied tenfold. 'Green revolution' could take place in a country like India. It was through the application of knowledge of chemistry that the methods of farming could be improved. The most important factor in the modernisation of agriculture was the use of fertilizers which helped the growth of plants. What are fertilizers? How do they act?

Fertilizers

• Plants get elements like carbon, hydrogen, oxygen etc. which are essential for their growth, from the atmosphere and water. Besides these elements, sodium, potassium and phosphorous and small quantities of calcium, magnesium and sulphur are also needed. Fertilizers are used mainly to provide these elements. The elements contained in the soil are lost through rain water and repeated farming. Elements needed by the plants can be immediately made available through fertilizers. It has been observed that agricultural yield more than doubles if fertilzers are used in the proper way.
• Nitrogen, phosphorous and potassium are the most important constituents of fertilizers. Fertilizers are classified into three types nitrogen fertilizers, phosphorous fertilizers and potassium fertilizers. The problems that arise due to lack of these elements and the fertilizers that can be used in such situations are given in table below.

SURERCONDUCTIVITY 

• Superconductivity, phenomenon displayed by certain conductors that demonstrate no resistance to the flow of an electric current. Superconductors also exhibit strong diamagnetism; that is, they are repelled by magnetic fields. Superconductivity is manifested only below a certain critical temperature Tc and a critical magnetic field Hc, which vary with the material used. Before 1986, the highest Tcwas 23.2 K (-249.8° C/-417.6° F) in niobium-germanium compounds. Temperatures this low were achieved by use of liquid helium, an expensive, inefficient coolant. Ultra low-temperature operation places a severe constraint on the overall efficiency of a super-conducting machine. Thus, large-scale operation of such machines was not considered practical. But in 1986 discoveries at several universities and research centers began to radically alter this situation. Ceramic metal-oxide compounds containing rare-earth elements were found to be super conductive at temperatures high enough to permit using liquid nitrogen as a coolant. Because liquid nitrogen, at 77K (-196° C/-321° F), cools 20 times more effectively than liquid helium and is 10 times less expensive, a host of potential applications suddenly began to hold the promise of economic feasibility. In 1987 the composition of one of these super conducting compounds, with Tcof 94K (-179° C/-290° F), was revealed to be (Y0.6Ba0.4)2CuO4. It has since been shown that rare-earth elements are not an essential constituent, for in 1988 a thallium-barium-calcium copper oxide was discovered with a Tc of 125K (-148° C/-234° F). See also Cryogenics.

IMPORTANCE OF CHEMISTRY IN EVERYDAY LIFE

• Some major contribution of chemistry to life in the modern world are:

  1.    Its Contribution to Improve health: Modern chemical discoveries have done a lot to eradicate disease and improve health, some important contributions are:

  (i)    Anaesthetics and Antiseptics: Discovery of anaesthetics and antiseptics has gone a long way in saving millions of lives. It made serious operations possible, as they could now be carried out painlessly and without fear of the wound getting ‘septic’ poisoned in any way.

  (ii)   Disinfectants and Germicides: The use of disinfectants and germicides helps us to prevent spread of diseases.

  (iii)  Drugs and Antibiotics: Discovery of Sulphur drugs and Penicillin, made pneumonia a curable disease. Antibiotics like streptomycin, Aureomycin and Chloromycentin have enable us to cure TB and so many other aliments.

  (iv)  Prophylactics: Use of prophylactics (disease preventing serums and vaccines) has made epidemics like plague, small pox, and cholera things of the past. Some latest prophylactics are slack Vaccine employed in the fight against polio and cytillen for treatment of diseases of the circulatory system.

  2.    Supply of Foodstuffs: (i) Fertilizers: The fertilizers enrich ours soil, plants need mainly nitrogen, phosphorus, and potassium for their growth, chemical compounds containing these elements are added to the soil and keep it fertile.

  (ii)   Insecticides: Insecticides spray on plants to save them from being eaten away or spoilt by various insects. Introduction of powerful insecticides like DDT and Methoxychlor has rendered the storage of grains safer.

  (iii)  Preservation: Fruits and vegetables which could not be kept for even a few days, can now be preserved and used after months, there are all application of chemistry.

  (iv)  Preventing Adulteration: A chemist is toiling in the laboratory testing our foodstuff for adulterants and improving them.

  3.    Increase in Comfort, Convenience and Pleasure: In every walk of life the chemist has been the pioneer contribution towards the happiness of man, he has helped us in getting a number of amenities, for example.

  (i)    Domestic Requirements: We look up to a chemist for most of domestic requirements e.g. payment fabrics (rayon, nylon), soap, dyes and perfumes etc.

  (ii)   Air Conditioning: To keep effects in all seasons, we make use of air condition. In this, we use chemical substances like liquid ammonia or liquid sulphur dioxide etc.