Question

give a brief description of the principle of the following technique taking an example in each case:
1. chromatography
2.crystallisation

Answer 1

Chromatography is used to separate mixtures of substances into their components. All forms of chromatography work on the same principle. They all have a stationary phase (a solid, or a liquid supported on a solid) and a mobile phase (a liquid or a gas).

The principle behind the crystallisation is that the amount of solute that can be dissolved by a solvent increases with temperature. In crystallisation, the impure substance is dissolved in a suitable solvent to reach its nearly saturated solution at a temperature higher than the room temperature.

Answer 2

HEY MATE HERE IS YOUR ANSWER:-

•Chromatography:-
(1) The technique of separating the components of a mixture in which separation is achieved by the differential movement of individual components through a stationary phase under the influence of a mobile phase.
(2) The stationary phase can be either a solid or tighly bound liquid on a solid support while the mobile phase can be either liquid or a gas.
(3) There are two types of adsorption chromatography :
(i) Column chromatography
(ii) Thin layer chromatography
The paper strip so developed is called the chromatogram.

•Crystallisation :-
(1) The process by which an impure compound is converted into its crystals is known as crystallisation.
(2) The impure substance is dissolved in a suitable solvent in which it is sparingly soluble at room temperature.
(3) The solution is concentrated to get nearly a saturated solution. When this saturated solution is cooled, crystals of the pure substance will separate out. Impure sugar is purified by this method.


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