Chemistry and its applications

Notes to remember
Common salt is obtained from sea water by the process of evaporation.
Gasoline is obtained from crude oil by the process of fractional distillation.
Benzene, carbon tetrachloride and trichloroethylene are used as dry cleaning chemicals.
Washing soda is hydrated sodium carbonate.
Carborundum is a compound of silicon.
Caffeine, a constituent of tea and coffee is a diuretic.
Citric acid is used in soft drinks.
Water, on passing over rocks, becomes hard because it dissolves calcium carbonate.
The process of changing one element into another is called transmutation of the elements.
Chemically, baking soda is sodium bicarbonate.
Laundry soap is a mixture of sodium salts of higher fatty acids of natural origin.
Synthetic detergents are a mixture of sodium salts of aromatic and aliphatic sulphonic acids.
Detergents produce lather with hard water because the calcium and magnesium salts of sulphonic acid are soluble in water.
Lime water contains calcium hydroxide.
Ozone is an allotropic form of oxygen.
Phosphorus is present in DNA and RNA.
Cooking oil can be converted into vegetable ghee by the process of hydrogenation.
Diamond is chemically pure carbon.
Nitrogen in air dilutes oxygen, which is otherwise very active in pure form.
Two solutions are said to be isotonic when they have the same osmotic pressure.
Cooking gas supplied in cylinders by gas agencies is in the form of liquid.
Cooking gas is a mixture of butane and propane.
Structurally silk is a polyamide.
The gas inside an electric bulb is nitrogen.
The elements 30Si14,31P15 and 32S16 are called isotones.
The absolute zero temperature is the lowest temperature that is theoretically possible.
Cellulose is a polysaccharide.
The most abundant gas in the atmosphere is nitrogen.
In order to prevent the corrosion of the iron popes, they are often coated with a layer of zinc. This process is termed as galvanization.
The main chemical substance present in the bones and teeth of animals is calcium phosphate.
Chemically, dry ice is solid carbon dioxide.
A gas which is not present in normal samples of air is chlorine.
A catalyst is a substance which increases the speed of a reaction.
Marsh gas, formed from decaying organic matter and in coal mines is methane.
Rice is not a good source of nutritional calcium.
Ragi, skimmed milk and eggs are good sources of nutritional calcium.
Vinegar is acidic in nature due to the presence of acetic acid.
The acid present in lemons and oranges is citric acid.
Water for civil supplies is commonly purified by chlorination.
During fermentation of sugar, the chief compound always formed is ethyl alcohol.
Animal charcoal is obtained by burning the bones of animals out of contact with air.
The substance that is added to make natural rubber strong and more bouncy is sulphur.
Photographic plates are covered with black paper because the silver bromide present on the plate is very sensitive to light and black paper prevents contact with light.
'Chlorination' is adding small amounts of chlorine to contaminated water.

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