Do you know? ( Interesting Science)

  • A solution of slaked lime produced by the reaction ( Ca(OH)2 + CO2 -----> CaCo3 + H2O) is used for whitewashing walls. Calcium hydroxide ( Ca(OH)2) reacts slowly with the carbon dioxide in the air to form a thin layer of calcium carbonate (CaCo3) on the walls. Calcium carbonate is formed after two to three days of whitewashing and gives a shiny finish to the walls. It is interesting to note that the chemical formula for marble is also CaCo3.

  • All bases do not dissolve in water. An alkali is a base that dissolves in water. They are soapy to touch, bitter and corrosive. Never taste or touch them as they may cause harm.

  • The atmosphere of Venus is made up of thick white and yellowish clouds of sulphuric acid.

  • Nettle is a herbaceous plant which grows in the wild. Its leaves have stinging hair, which causes painful stings when touches accidentally. This is due to the methanoic acid secreted by them. A traditional remedy is rubbing the area with the leaf of the dock plant, which often grows beside the nettle in the wild.

Nettle or Dock plant

  • Anodising is a process of forming a thick oxide layer of aluminium. Aluminium develops a thin oxide layer when exposed to air. This aluminium oxide coat makes it resistant to further corrosion. The resistance can be improved further by making the oxide layer thicker. During anodising, a clean aluminium article is made the anode and is electrolysed with dilute sulphuric acid. The oxygen gas evolved at the anode reacts with aluminium to make a thicker protective oxide layer. This oxide layer can be dyed easily to give aluminium articles an attractive finish.

  • Aqua regia, (Latin for 'royal water') is a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3:1. It can dissolve gold, even though neither of these acids can do so alone. Aqua regia is a highly corrosive, fuming liquid. It is one of the few reagents that are able to dissolve gold and platinum.

  • Pure gold, known as 24-carat gold, is very soft. It is, therefore, not suitable for making jewellery. It is alloyed with either silver or copper to make it hard. Generally, in India, 22-carat gold is used for making ornaments. it means that 22 parts of pure gold is alloyed with 2 parts of either copper or silver.

  • The iron pillar near the Qutub Minar in Delhi was built more than 1600 years ago by the ironworkers of India. They had developed a process which prevented iron from rusting. For its quality of rust resistance it has been examined by scientists from all parts of the world. The iron pillar is 8 m high and weighs 6 tonnes (6000 kg).

  • The element carbon occurs in different forms in nature with widely varying physical properties. Both diamond and graphite are formed by carbon atoms, the difference lies in the manner in which the carbon atoms are bonded to one another. In diamond, each carbon atoms is bonded to four other carbon atoms but in graphite, each carbon atom is bonded to three other carbon atoms. 

  • Coal and petroleum have been formed from biomass which has been subjected to various biological processes. Coal is the remains of tree, ferns, and other plants that lived millions of years ago. These were crushed into the earth, perhaps by earthquakes or volcanic eruptions. They were pressed down by layers of earth and rock. They slowly decayed into coal. Oil and gas are the remains of millions of tiny plants and animals that lived in the sea . When they died, their bodies sank to the sea bed and covered by silt. Bacteria attacked the dead remains, turning them into oil and gas under the high pressure they were being subjected to. Meanwhile, the silt was slowly compressed into rock. The oil and gas seeped into the porous parts of the rock, and got trapped like water in a sponge.

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