Techniques of separation, Class 9


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Class 9 Separation techniques
Evaporation , Sublimation, chromatography, Distillation, Fractional distillation, Crystallization; Are the various methods being talked abut in detail in the ppt along with their applications with the help of activities.
By this We can separate the non-volatile component (solute) from its volatile solvent

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Techniques of separation, Class 9

  1. 1. Impure substances: Mixtures
  2. 2. Separation Of Mixtures
  3. 3. Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid. With sufficient heat, the liquid would turn into vapor quickly. APPLICATIONS:-When clothes are hung on a laundry line, even though the ambient temperature is below the boiling point of water, water evaporates. This is accelerated by factors such as low humidity, heat, and wind..
  4. 4.  Aim: To obtain coloured component(dye) from its volatile solvent by the method of evaporation.  Materials : A beaker, a watch glass, a burner, water and some blue ink.  Procedure: 1. Fill half a beaker with water. o 2. Cover it with a watch glass, put a few drops of ink on it and heat it. o 3. Evaporation starts from the watch glass. o 4.Continue to heat till you see that there are no further changes on the watch glass.  Observation: The water gets evaporated from the watch glass and residue is left . Therefore it is not a single substance but a mixture of dye in water.
  5. 5. By Separating Funnel  A mixture of two immiscible liquids can be separated by using a Separating Funnel.  The Separation of two immiscible liquids by a separating funnel is based on the difference in their densities…..  : The mixture is put into a separating funnel, shaken and allowed to settle. The oil and water from two separate layer. The liquid with higher density, in this case water forms the lower layer. Remove the stopper and open the tap after standing. The water runs out through the tap. The oil remains in the funnel and can be run out into another beaker.
  6. 6. : To separate kerosene oil from water using a separating funnel… : 1. Pour the mixture of oil and water in a separating funnel.  Do not disturb it till layer of oil and water is formed.  Opening the stop clock of the funnel, pour the lower level of water carefully.  Close the stop clock as the soil reaches the it and is left behind in the separating funnel. : We conclude that immiscible liquids can be separated with the help of separating funnel…
  7. 7.  Most of the solids substances when heated changes into liquid and finally into Vapours (or gas).  This vapour on cooling ,first forms liquid and finally the solids.  On the other hand there are some solid substances like ammonium chloride which directly changes into vapours on heating and the vapours gives back solid substance on cooling.  The change of a solid directly into a vapour on heating and of the vapuor into solids on cooling is known as Sublimation ….
  8. 8.  Aim:-To separate a mixture of salt and ammonium chloride..  Procedure:- 1 The mixture of ammonium chloride and salt is taken in a china dish and covered with an inverted funnel.  A loose cotton plug is put in the stem of the funnel to prevent the ammonium chloride vapours from escaping in the atmosphere.  On heating ammonium chloride changes into vapours. These vapours condense on the cold inner side of the funnel to give back solid ammonium chloride..  Sodium Chloride does not vaporise on heating so it remains behind in the china dish….
  9. 9. Distillation  Distillation is the process of heating a liquid to form vapour and then cooling the vapour to get back the liquid… Heating  Liquids Vapours(or gas) Cooling  The liquid obtained by condensing the vapours is called distillate.  Process in which the components of a substance or liquid mixture are separated by heating it to a certain temperature and condensing the Resulting Vapors…..
  10. 10.  Aim: To separate alcohol and water from their solution.  Procedure: 1 Take the solution in a distillational flask fitted with fractionating column. Fit it with a thermometer.  Arrange it like the that done in the picture..  Heat the mixture slowly keeping a close watch at the thermometer reading.  The alcohol evaporates, condenses in the condenser and can be collected from the condenser outlet.  Water is left behind in the distillation flask…..  Observation: By this method alcohol and water are separated… Picture on next page!!!
  11. 11. Chromatography  The process of separation of component of a mixture is know as Chromatography .  Chromatography is the technique used for the separation of those solutes that dissolve in the same solvent….. Crystallization  The substances when present in well defined geometrical shapes Are called crystals. These are formed when a hot saturates solution of salt is allowed to cool slowly and undisturbed.  The process of preparation of crystals is termed as crystallization…..