Chemistry

Matter in Our Surroundings


2. Separation by Sublimation


We have already studied the process of sublimation in the previous chapter. We know that the changing of a solid directly into vapours on heating, and of vapours into solid on cooling is called sublimation.The solid substance which undergoes sublimation is said to 'sublime'. The process of sublimation is used to separate those substances from a mixture which sublime on heating. The solid substance obtained by cooling the vapours is known as 'sublimate'. The substances like ammonium chloride, iodine, camphor,naphthalene and anthracene sublime on heating and can be recovered in the form of a sublimate by cooling their vapours. This means that ammonium chloride,iodine, camphor, naphthalene and anthracene change directly from solid to vapours on heating, and from vapours to solid on cooling.
Most of the solid substances do not undergo sublimation.For example, substances such as common salt (sodium chloride), sand, iron filings, sulphur and chalk, etc., do not sublime on heating. The process of sublimation is used to separate that component of a solid-solid mixture which sublimes on heating (the other component of the mixture being non-volatile). Thus,ammonium chloride,iodine, camphor,naphthalene and anthracene can be separated from a mixture by sublimation. This will become more clear from the following example.

--- >>>

Notes


Matter in Our Surroundings - Notes
1. 9. Non-Metals Have Low Densities.
Show Notes
2. 7. Metals are Solids at the Room Temperature
Show Notes
3. Properties of Metals
Show Notes
4. 2. Metals are Ductile.
Show Notes
5. 3. Non-Metals are Bad Conductors of Heat and Electricity.
Show Notes
6. Concentration of a Solution
Show Notes
7. 3. Separation by a Magnet
Show Notes
8. 11. Non-Metals Have Many Different Colours.
Show Notes
9. 7. Non-Metals may be Solid, Liquid or Gases at the Room Temperature.
Show Notes
10. The Case of Solutions
Show Notes
11. 5. Non-Metals are Generally Soft
Show Notes
12. Elements
Show Notes
13. Non-Metals
Show Notes
14. Impure Substances: Mixtures
Show Notes
15. 8. Metals Generally Have High Melting Points and Boiling Points.
Show Notes
16. Is Matter Around Us Pure
Show Notes
17. 1. Metals are Malleable.
Show Notes
18. 2. Separation by Centrifugation
Show Notes
19. 8. Non-Metals Have Comparatively Low Melting Points and Boiling Points
Show Notes
20. Types of Solutions
Show Notes
21. Physical And Chemical Changes
Show Notes
22. 6. Separation by Distillation
Show Notes
23. 1. Non-Metals are Not Malleable. Non-Metals are Brittle.
Show Notes
24. To Study the Properties of a Suspension
Show Notes
25. Effect of Temperature and Pressure on Solubility
Show Notes
26. Chemical Formula for daily use material
Show Notes
27. Pure Substances : Elements and Compounds
Show Notes
28. Properties of a Suspension
Show Notes
29. Separation of Scrap Iron
Show Notes
30. Supply of Drinking Water in a City
Show Notes
31. Solutions
Show Notes
32. 1. Separation by a Suitable Solvent
Show Notes
33. Solutions, Suspensions And Colloids
Show Notes
34. properties of a Solution
Show Notes
35. Colloids
Show Notes
36. 4. Non-Metals are Not Lustrous (Not Shiny). They are Dull in Appearance.
Show Notes
37. Mixtures
Show Notes
38. 3. Metals are Good Conductors of Heat and Electricity.
Show Notes
39. Suspensions
Show Notes
40. 5. Separation by Chromatography
Show Notes
41. Metals, Non-Metals and Metalloids
Show Notes
42. 10. Metals are Sonorous.
Show Notes
43. Properties of Non-Metals
Show Notes
44. To Separate the Salt-Water Mixture (or Salt-Solution)
Show Notes
45. Metals
Show Notes
46. 2. Non-Metals are Not Ductile.
Show Notes
47. Comparison Among the Properties of Metals and Non-Metals
Show Notes
48. Compounds
Show Notes
49. Differences Between Mixtures and Compounds
Show Notes
50. The Case of Alloys
Show Notes