how the fractional distillation and centrifugation techniques differ from each other
Answers
Answer:
1) Centrifugation is a technique used for the separation of particles from a solution according to their size, shape, density, viscosity of the medium and rotor speed.
The particles are suspended in a liquid medium and placed in a centrifuge tube. The tube is then placed in a rotor and spun at a define speed.
Separation through sedimentation could be done naturally with the earth gravity, nevertheless, it would take ages. Centrifugation is making that natural process much faster.
Rotation of the rotor about a central axis generates a centrifugal force upon the particles in the suspension.
Which factors have an influence on centrifugation :
Density of both samples and solution
Temperature/viscosity
Distance of particles displacement
Rotation speed
A centrifuge is a device that separates particles from a solution through use of a rotor. In biology, the particles are usually cells, subcellular organelles, or large molecules, all of which are referred to here as particles.
There are two types of centrifuge procedures; one is preparative, the purpose of which is to isolate specific particles, and the other is analytical, which involves measuring physical properties of the sedimenting particles.
As a rotor spins in a centrifuge, a centrifugal force is applied to each particle in the sample; the particle will then sediment at the rate that is proportional to the centrifugal force applied to it. The viscosity of the sample solution and the physical properties of the particles also affect the sedimentation rate of each particle.
At a fixed centrifugal force and liquid viscosity, the sedimentation rate of a particle is proportional to its size (molecular weight) and to the difference between the particle density and the density of the solution.
2) Fractional distillation is a technique for the separation of miscible liquids. It is a distillation technique used for the separation of liquids which dissolve in each other. Fractional distillation is a process of separating the components of a mixture by repeated distillations and condensations.
Fractional distillation column is a fractionating column used for the separation of miscible liquids. It is a long glass tube with wide bore. It either filled with glass beads, small stones, porcelain rings or coke. It can also be blown in to a shape with several spheres or pear bulbs. The purpose of the glass beads is that they improve the distillation process.
There can be several trays in the fractionating column in place of glass beads and bulbs. These trays are called theoretical plates. Theses trays or theoretical plates serve the purpose of the glass beads.
For commercial purpose fractionating column with hundredth of theoretical plates are used. The main aim of using the fractionating column is to increase the surface area for cooling of liquid and to provide hurdles to the rising vapours and descending liquid.
The principle of fractional distillation is that different liquids boil at different temperature. The miscible liquids boil at different temperature and evaporate at different temperature.
When the mixture is heated, the liquid with lower boiling point boils and turns into vapours. So the mixture is heated to a temperature at which one or two components of the mixture will vaporise. Fractional distillation involves repeated distillations and condensations.
Uses:
One of the important use of using fractional distillation is to separate the crude oil into its various components such as gasoline, kerosene oil, diesel oil, paraffin wax, liberating oil.
Fractional distillation is also used for the purification of water. Water contains many dissolved impurities; these can be removed by this process.
It is also used for separating acetone and water.
Industrial use of fractional distillation is in petroleum refineries, chemical plants, natural gas processing and separation of pure gases from mixture of gases.
It has other industrial uses as it is used for purification and separation of many organic compounds.