6th Class Science Separation of Substances

Separation of Substances

Synopsis

• Matter can be broadly divided into two major groups "pure?? and "impure"

• Matter is made up of tiny particles called molecules. Molecules are further made of same or different kinds of atoms.

• Molecules of a substance have all the properties of that substance.

•  A pure substance is made up of only one type Of molecules and so it is called homogeneous substance, e.g., elements, compounds.

• An impure substance is made up of more than one type of molecules and it is called heterogeneous substance, e.g., mixtures.

•  A substance which is uniform in its composition and properties throughout is called a homogeneous substance.

•  A substance which is not uniform in its composition and properties throughout is called a heterogeneous substance.

• Methods of Separation: Some simple methods of separating substances that are mixed together are given below.         

•  Handpicking is used for separating slightly larger sized impurities like the pieces of dirt stones and husk from wheat, rice or pulses.

• Threshing is used to separate grain from stalks.

• Winnowing is used to separate heavier and lighter components of a mixture by wind or by blowing air. 

• Sieving makes the fine flour particles to pass through the holes of the sieve while the bidder impurities remain on the sieve.

• Sedimentation settles the heavier component in a mixture after water is added to it.

• Filtration is used to separate components of a mixture of an insoluble solid and a liquid.

• Evaporation is the process of conversion of water into its vapour.

• Condensation is the process of conversion of water vapour into its liquid form.

• Saturated solution is the one in which no more of a substance can be dissolved.

• Sometimes, a combination of methods are to be used to separate mixtures of more than two substances.

• Substances may need to be separated from each other to remove impurities or to get two or more useful products.

Methods of separation