Separation of Substances (Pure Substances and Mixtures)

A pure Substance consists of only one kind of particles.

A mixture consists of two or more kind of particles.

Water - Pure Substance

Sand - Mixture

Sand - Mixture

Types of Mixture

A homogeneous mixture is that which has the same composition throughout, that is, its components are uniformly distributed and cannot be distinguished from each other.

A heterogeneous mixture is that which does not have the same composition throughout, that is, its components are not uniformly distributed and can be distinguished from each other

Separating the components of Mixtures

a. Mixture of Solids with Solids

i. Hand Picking

The components of a solid-solid mixture can be separated by hand picking. For e.g. separating pebbles from rice or dal, separating grass from mint leaves.

ii. Threshing

This method is generally used by the farmers to separate the grains from the stalks after harvesting.The dried stalks are beaten or threshed to separate the grains. However, in large farms threshing is done by using threshing machines.

iii. Winnowing

In this method, the mixture is allowed to fall from a height. The lighten components get separated from the heavier ones because of wind or air blow. This method is used to separate lighter husk from heavierGrains like wheat.

Winnowing

iv. Sieving

This method is used to separate the components that are of different sizes. For sieving, a sieve is used.Sieve is a wire mesh fixed tightly in a frame.

v. Magnetic Separation

In this magnetic substances (like iron get attracted by the magnet. For e.g.- when a magnet is brought near iron pins, all pins get clinged to it.

vi. Sublimation

The process in which a solid changes directly into gaseous state on heating is called sublimation.

b. Mixture of solids with liquids

i. Evaporation

Evaporation is a process in which a liquid changes into gaseous form on heating is called evaporation.

ii. Crystallization

Crystallization is a process which separates a pure solid in the form of its crystals from a saturated solution.

i. Sedimentation and Decantation

2. Separating solids that do not dissolve in liquids

Sedimentation is the process by which the insoluble, heavy solid particles settle down their own in a solution. In order to separate the two, the liquid has to be gently poured into another container without disturbing the sediments. This process of obtaining clear liquid by pouring it into another container without disturbing the sediments is called decantation.

ii. Loading

Loading is a process which speeds up the sedimentation. In fact, loading is a faster process as compared to sedimentation.

iii. Filtration

Filtration is a process of separating insoluble solids (like mud, tea leaves etc.) from a liquid using fine pores of the filter.

Separating immiscible liquids

It is a mixture of two liquids which do not mix with each other.

MADE BY: RITISHA SINGH

CLASS: 6th C

ROLL NO: 27