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CHEMISTRY FORM 1


i Common Chemistry Laboratory Chemicals
ii Common Chemistry Laboratory Apparatus
iii Safety in the Chemistry Laboratory
iv Why we should learn Chemistry
1. INTRODUCTION TO CHEMISTRY
2. SIMPLE CLASSIFICATION OF SUBSTANCES AND SEPERATION OF MIXTURES
3. ACIDS, BASES AND INDICATORS
4. AIR AND COMBUSTION
5. WATER AND HYDROGEN
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Air and Combustion: Fractional distillation of liquid air

4.0 Air and Combustion


4.2 Fractional distillation of liquid air

Fractional distillation is also used to separate components of air (nitrogen, oxygen, and rare gases). This is possible because the components have different boiling points.


fractional distillation of liquid air high school chemistry

Air is first condensed (liquefied). It then flows into a fractionating column where it is allowed to boil. The component with the lowest boiling point boils off first and its vapour is condensed and stored in a separate tank. The component with the next lowest boiling point is collected next and so on.


NB: During liquefaction, carbon (IV) oxide sublimes (deposits) at -78 °C and is removed as a solid.


Questions 4.2

  1. Which component of air will be:
    1. the first to liquefy during cooling
    2. the last to liquefy during cooling
    3. the first to boil during distillation?
  2. Search the Internet for
    1. two uses of helium
    2. one use of argon
    3. one use of neon
    4. one use of carbon (IV) oxide.

Answers to Questions 4.2


It is through fractional distillation that the oxygen used in hospitals on patients with breathing difficulty is prepared.