STPM Chemistry Form 6 Notes – Phase Equilibrium (Part 10 – Final)

by BerryBerryTeacher

in Berry Reference (Notes)

Chromatography is techniques used in laboratories for the separation or analysis of complex mixture. While it is easy to understand what chromatography does but not many knows the process in simple terms. So how does chromatography works? Berry Berry Easy would say that it is simply a process (will use a generic example) where: when a mixture with many different components undergoes a chromatography process, the components move through the system at different rates. The difference in rates between the components are due to how it reacts (adsorption and desorption) to the adsorptive materials (stationary bed), which in turn provides the separation. Unlike most of the other separation method, chromatography allows separation of complex mixture with great precision. So it can be used for analysis of samples. It’s applications abound in the field of biotechnology, primarily made famous by the separation of protein mixtures.

So Berry Berry Easy would like to share this final part, Part 10 of the STPM Chemistry Form 6 notes on Phase Equilibrium which focuses on adsorption chromatography and partition chromatography. It’s not a difficult topic so you can breeze through this final part in the series.

[Tips: In previous years, some of the more hardworking students went over-zealous to read up on the details of all the special techniques of chromatography such as the pyrolysis gas chromatography, reverse-phase chromatography, chiral chromatography and counter-current chromatography. While it'll be useful to know it for general knowledge, but writing it in heavy detail for essay questions do not bring that many extra marks, if any. So it is better to focus on just adsorption and partition chromatography for now. You can go in detail when you enter university.]

STPM Chemistry Form 6 Notes – Phase Equilibrium (Part 10 – Final)

Fractional Distillation

Fractional Distillation

Chromatography

  • Definition: Chromatography – technique used to separate the mixture of components by distributing the mixture between two immiscible phase, the stationary phase and the mobile phase.
  • Types of chromatography: adsorption chromatography & partition chromatography

Adsorption chromatography

  • Stationary phase = solid
  • Mobile phase = liquid or gas
  • Mixture of components are adsorbed on the surface of the stationary phase
  • Example: column chromatography, thin layer chromatography (TLC)

Partition chromatography

  • Stationary phase = non-volatile liquid film supported on an inert solid
  • Mobile phase = liquid or gas
  • Mixture of components are partitioned between the liquid film and the mobile phase (Used partition coefficient / distribution coefficient, K)
  • Interpretation: high value K = the component (X) dissolves more readily in the mobile phase and the component moves rapidly along the stationary phase.
  • Interpretation: low value K = the component (X) remain largely adsorbed on the stationary phase and the components moves slowly along the stationary phase.
  • Example: paper chromatography, gas-liquid chromatography (GLC)

Application of chromatography

  • Separate mixture components
  • Identify components
  • Determine the purity of a substance

Example:

  • Pigments from plant
  • Antibiotics from fungi
  • Amino acids

Finally, we are done with the long series of notes on Phase Equilibrium. Berry Berry Easy hopes that you understand all parts in this chapter.

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