Separation of Mixtures
To separate the components of a mixture using the following techniques:
•Separating funnel
•Chromatography
•Centrifugation
•Simple distillation
•Fractional distillation
The Theory
How is a homogeneous mixture different from a heterogeneous mixture?
Most materials in our surroundings are mixtures of two or more components.
Mixtures are either homogeneous or heterogeneous. Homogeneous mixtures are
uniform in composition,
but heterogeneous mixtures are not uniform in composition.
Air is a homogeneous mixture and oil in water is a heterogeneous mixture. Homogeneous
and heterogeneous mixtures can be separated into their components by several physical
methods. The choice of separation techniques is based on the type of mixture and difference in the chemical properties of the constituents of a mixture.
What are types of separation techniques?
Various types of separation processes are:
•Crystallization
•Filtration
•Decantation
•Sublimation
•Evaporation
•Simple distillation
•Fractional distillation
•Chromatography
•Centrifugation
•Separating funnel
•Magnetic separation
•Precipitation
Using a separating funnel:
A separating funnel is used for the separation of components of a mixture between two immiscible liquid phases. One phase is the aqueous phase and the other phase is an organic solvent. This separation is based on the differences in the densities of the liquids. The liquid having more density forms the lower layer and the liquid having less density forms the upper layer.
Applications:
•To separate a mixture of oil and water.
•To separate a mixture of kerosene oil and water.
Chromatography:
Chromatography is a separation technique used to separate the different components in a liquid mixture.
It was introduced by a Russian Scientist Michael Tswett. Chromatography involves the sample being dissolved in a particular solvent called mobile phase. The mobile phase may be a gas or liquid. The mobile phase is then passed through another phase called stationary phase. The stationary phase may be a solid packed in a glass plate or a piece of chromatography paper.
The various components of the mixture travel at different
speeds, causing them to separate. There are different types of chromatographic techniques such as column chromatography, TLC, paper chromatography, and gas chromatography.
Paper chromatography is one of the important
chromatographic methods. Paper chromatography uses paper as the stationary phase and a liquid
solvent as the mobile phase. In paper
chromatography, the sample is placed on a spot on the paper and the paper is carefully dipped into a solvent. The solvent rises up the paper due to
capillary action and the components of the mixture rise up at different rates and thus are separated
from one another.
