| Experiments to prove the presence of different components of air |
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Nitrogen:
Burn a piece of magnesium in an open glass jar. A pale yellow solid (a mixture of MgO and Mg3N2) is deposited inside the jar.
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Pour hot water over this pale yellow solid. It liberates a smell resembling ammonia gas.
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Place a glass rod dipped in conc. HCl at the mouth of the jar. Thick white fumes are produced. Presence of ammonia is confirmed. This proves that air contains nitrogen.
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Oxygen:
Nitric oxide (NO) is a colourless gas. When it is allowed to mix in air, it forms reddish brown gas, nitrogen dioxide. This proves that air contains oxygen.
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Carbon dioxide: Draw air through limewater placed in a test tube. Limewater turns milky due to the formation of white insoluble calcium carbonate. This proves presence of carbon dioxide in air. |
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Moisture: Place ice in a glass tumbler or beaker. Droplets of colourless liquid are seen to condense on the outer walls of tumbler. Collect a few of these drops in a watch glass and treat them with anhydrous copper sulphate. The white anhydrous copper sulphate turns blue. This confirms the colorless liquid must be water. |
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Dust Particles: One can see dust particles floating in the air when a beam of sunrays passes through a narrow hole into a dark room. |
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