Materials in Our Daily Life : 95 :
Materials in Our Daily Life
The basic aim of science is not only to study and understand natural phenomena but also to use this knowledge to make our lives more comfortable. Science and technology have enabled us to develop more economical and convenient methods to recover useful materials from nature and to put them to various uses. Chemistry has enabled us to synthesize new materials which have desired properties, thus, making them even better than natural materials. We need different types of materials to meet our daily needs. Some of them are obtained from nature while others are prepared by man. The materials that we get from nature are called natural materials. Wood, silk, cotton, leather, rubber, coal, etc. are natural materials. However, some materials that we use are manmade. Synthetic textiles like terylene and nylon, cement, glass, plastics, dyes, soap, detergents, fertilizers, insecticides and pesticides are some man-made materials which are commonly used. In this lesson, you will learn about the ways in which various materials are used in making common household items, in construction of houses and other buildings. You will learn about different polymers and their uses in our daily life. In addition, you will learn about the various medicines that help to cure different diseases and keep us healthy. OBJECTIVES After completing this lesson, you will be able to: • differentiate between natural and man-made materials; • name the materials used for making some common household items and for housing purposes; • state the principles involved in preparation and properties of some man-made materials in our daily life; • list various medicines used in some common diseases; • explain harmful effects of man-made materials on the environment. 21.1 COMMON HOUSEHOLD ITEMS We use many things in our house like candles in case of emergency lighting, ink to write, soaps and detergents to wash our clothes, matchbox to light gas stove or candles and many more. Let us now learn about these items of daily use.
: 96 : Materials in Our Daily Life
21.1.1 Candles We use candles as emergency light source and for decorative and ceremonial purposes. Usually they are made from a mixture of paraffin wax or some other slow-burning substance like tallow (stearic acid). They are commonly made in cylindrical form but are also made in fanciful designs. They contain a wick at their centre. When lighted with a matchstick heat from its flame liquefies the wax of the candle. This liquefied wax rises up along the wick where it is converted into vapour form, which then catches fire. Now a days, candles are made in a variety of colours, shapes and sizes. Some candles are scented and their aroma spreads in the air when lighted while some others can float on water. Nainital (in Uttaranchal) is famous for the variety of beautiful and decorative candles manufactured here. 21.1.2 Inks We all use inks in various writing instruments like fountain pens, ball pens, gel pens, roller pens, soft tip pens, etc. Have you ever thought what ink is? Ink is a coloured fluid or a paste that is used for writing or printing. Earlier, black ink, also called India ink, was most widely used. It was made by mixing lamp black or carbon black in water or oil to which some gum was added which stabilized the mixture and also gave it better sticking property. This ink is used even these days but more commonly used inks are solutions of water or alcohol soluble dyes. Inks used in printing are similar in nature but are in the form of thick paste, which has a better sticking property. This is an essential quality as it causes the ink to stick to the typefaces and to paper when it is pressed against it. 21.1.3 Soap and detergents We use soap and detergents to wash our clothes. We wash our hands and take bath with soap. Soap and detergents help in removing dirt, oil and grease. How do soap and detergents remove the dirt and grease? What...
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