Chemistry

Matter in Our Surroundings


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1.The air is first filtered to remove dust, then water vapour and carbon dioxide are removed (If water vapour and carbon dioxide are not removed, they would become solid in the cooling process and block the pipes).
2.Air is compressed to a high pressure and then cooled. This cooled air is then allowed to expand quickly into a chamber through a jet. This expansion cools the air even more.
3.The process of compression, cooling and rapid expansion of air is repeated again and again making the air more and more cool. Ultimately the air gets so cooled that it turns into a liquid. In this way,liquid air is obtained.
4.The liquid air is fed into a tall fractional distillation column from near its bottom and warmed up slowly.
(a) Liquid nitrogen (present in liquid air) has the lowest boiling point of, -196°.So, on warming,liquid nitrogen boils off first to form nitrogen gas. This nitrogen gas is collected from the top part of the fractional distillation column.
(b) Liquid argon (present in liquid air) has a slightly higher boiling point of, -186° So, liquid argon boils off next and collected as argon gas in the middle part of the fractional distillation column.
(c) Liquid oxygen (present in liquid air) has a still higher boiling point of, -183°.So, liquid oxygen boils off last and collected as oxygen gas from the bottom of the fractional distillation column.
A flow diagram showing the main processes involved in obtaining different gases from air is given below :

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Notes


Matter in Our Surroundings - Notes
1. 3. Non-Metals are Bad Conductors of Heat and Electricity.
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2. Saturated And Unsaturated Solutions
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3. 7. Metals are Solids at the Room Temperature
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4. The Case of a Liquid Solute Dissolved in a Liquid Solvent
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5. 3. Separation by a Magnet
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6. 11. Metals Usually Have a Silver or Grey Colour
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7. 7. Non-Metals may be Solid, Liquid or Gases at the Room Temperature.
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8. 2. Metals are Ductile.
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9. 5. Non-Metals are Generally Soft
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10. 2. Non-Metals are Not Ductile.
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11. 6. Non-Metals are Not Strong. They Have Low Tensile Strength.
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12. 9. Metals Have High Densities.
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13. Separation Of Mixture Of a Solid And a Liquids
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14. To Study the Properties of a Colloid
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15. 9. Non-Metals Have Low Densities.
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16. 5. Metals are Generally Hard
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17. Physical Changes
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18. Non-Metals
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19. To Study the Properties of a Compound of Iron and Sulphur
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20. 1. Separation by a Suitable Solvent
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21. 11. Non-Metals Have Many Different Colours.
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22. Separation OF Mixtures
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23. Concentration of a Solution
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24. 1. Separation by Filtration
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25. 6. Metals are Usually Strong. They Have High Tensile Strength.
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26. Solutions
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27. Types of Solutions
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28. 2. Separation by Centrifugation
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29. 2. Separation by a Separating Funnel
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30. 3. Metals are Good Conductors of Heat and Electricity.
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31. To Distinguish a Colloid from a Solution
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32. Separation of Scrap Iron
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33. 5. Separation by Chromatography
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34. Experiment to Obtain Coloured Component (Dye) From Ink
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35. 1. Metals are Malleable.
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36. 10. Non-Metals are Not Sonorous.
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37. Supply of Drinking Water in a City
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38. To Study the Properties of a Solution
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40. 1. Separation by Fractional Distillation
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41. 1. Non-Metals are Not Malleable. Non-Metals are Brittle.
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42. Elements
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43. The Case of Alloys
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44. To Prepare a Saturated Solution
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45. 4. Purification by Crystallisation
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46. To Separate the Salt-Water Mixture (or Salt-Solution)
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47. Chemical Formula for daily use material
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48. Metals
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49. Properties of Metals
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50. Chemical Changes
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