Separation of the Gases of the Air
Air is a mixture of gases like nitrogen, oxygen, argon, carbon dioxide, helium, neon, krypton, and xenon, etc. The major component of air is nitrogen (78.03%). The second major component of air is oxygen (20.99%), and the third major component of air is argon (0.93%). All the remaining gases of air constitute only 0.05% of air. Nitrogen is used for making fertilisers. Oxygen is used for making steel in factories, and in hospitals (to help patients having breathing difficulties). Argon is filled in electric bulbs. All these gases are obtained from air on a large scale. This is because air is the cheapest source of these gases.
The various gases of air are separated from one another by the fractional distillation of liquid air. This separation is based on the fact that
the different gases of air have different boiling points (when in liquid form).The boiling points of the three major gases of air, nitrogen, oxygen and argon, are given below :
| Gas | Boiling point
(of liquefied gas) |
Nitrogen -196&de;C
Argon -186&de;C
Oxygen -183&de;C | Lowest Boiling point
Highest boiling point |
Liquid air is an extremely cold liquid. Liquid air contains all the component gases in the liquid form. When liquid air is warmed gradually during fractional distillation, the various liquefied gases present in it boil off at different temperatures (according to their boiling points) and collected separately at different heights in the fractional distillation column. We will now describe how gaseous air is converted into liquid air, and how the three major components, nitrogen, oxygen and argon, are separated from it.
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Matter in Our Surroundings - Notes
2. 7. Metals are Solids at the Room Temperature
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5. 3. Non-Metals are Bad Conductors of Heat and Electricity.
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8. 11. Non-Metals Have Many Different Colours.
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9. 7. Non-Metals may be Solid, Liquid or Gases at the Room Temperature.
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16. 8. Metals Generally Have High Melting Points and Boiling Points.
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19. 8. Non-Metals Have Comparatively Low Melting Points and Boiling Points
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23. To Study the Properties of a Suspension
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24. Effect of Temperature and Pressure on Solubility
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25. Chemical Formula for daily use material
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26. 1. Non-Metals are Not Malleable. Non-Metals are Brittle.
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32. Pure Substances : Elements and Compounds
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33. 3. Metals are Good Conductors of Heat and Electricity.
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34. 4. Non-Metals are Not Lustrous (Not Shiny). They are Dull in Appearance.
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37. 1. Separation by a Suitable Solvent
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38. Solutions, Suspensions And Colloids
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46. Differences Between Mixtures and Compounds
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48. Separation Of Mixture Of a Solid And a Liquids
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50. To Separate the Salt-Water Mixture (or Salt-Solution)
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