This PSEB 6th Class Science Notes Chapter 5 Separation of Substances will help you in revision during exams.
PSEB 6th Class Science Notes Chapter 5 Separation of Substances
→ Substances around us can be pure substances or impure substances. Impure substances are also known as mixtures.
→ A pure substance is made up of only one type of atom or molecule, e.g. water. It has definite composition and properties.
→ Some mixtures have some desired substances and undesired substances.
→ We must separate undesired substances from desired substances.
→ The process of separating different substances from a mixture is known as separation.
→ The separation must be done if it has undesired substances. This is because undesired substances in the mixture can be harmful to us.
→ Separation is important in those cases where we need a particular component in a pure state.
→ We have many methods for separating components of a mixture.
→ These are based upon differences in the properties of substances present in the mixture.
→ Different methods of separation are Hand-picking, Threshing, Winnowing, Sieving, Sedimentation, Decantation, Filtration, Evaporation, etc.
→ Hand-picking is used to separate the components of a mixture if we can see these with f naked eye and these are large in size.
→ The combine is used for both the harvesting and threshing process.
→ Threshing is the separation of grains from the chaff. It can be done using any one method out of the three i.e.
- manual
- with the help of Animals
- using machines
→ Winnowing is a method to separate heavier and lighter components of a mixture by wind or by blowing air.
→ Methods like decantation, sedimentation, filtration, evaporation are used to separate mixtures of solids and liquids.
→ The process of settling down heavier, insoluble particles from a mixture is called sedimentation.
→ The substance that settles at the bottom is called sediment.
→ This method is used to separate insoluble heavier particles from a liquid.
→ The process of transferring the clear liquid without disturbing sediment is known as decantation.
→ The process of separating an insoluble solid from a liquid bypassing the liquid through a filter paper or muslin cloth is known as filtration.
→ The process of separating differently sized particles of a mixture using a sieve is called sieving.
→ The process of converting a liquid into its vapours by heating is called evaporation.
→ Sometimes we can or need more than one method for separating components of a mixture.
→ When a mixture of two or more substances appears like a single substance or pure substance it is called a solution.
→ In a solution, the substance present in a larger amount is called the solvent and the substance present in a smaller amount is called the solute.
→ A saturated solution is a solution in which no more solute can be dissolved at a particular temperature.
→ An unsaturated solution is a solution in which more solute can be dissolved at a particular temperature.
→ Water dissolves different amounts of substances in it and the solubility of most substances increases when the solution is heated.
→ Evaporation and condensation are opposite of each other.
→ Pure substance: If a substance is made up of only one type of component (atoms or molecules) it is called a pure substance. It must have definite composition and properties.
→ Impure substance: An impure substance is one that consists of a mixture of different types of molecules.
→ Mixture: A substance made up of two or more elements or compound mixed together in any ratio without any chemical reaction is called a mixture.
→ Solution: When a mixture of two or more substances appears like a single substance or pure substance it is called a solution.
→ Solvent: In a solution, the substance present in a larger amount is called the solvent.
→ Solute: In a solution, the substance present in smaller amounts is called the solute.
→ Saturated solution: A solution in which no more solute can be dissolved at a particular temperature is called a saturated solution.
→ Unsaturated solution: A solution in which more solute can be dissolved at a particular temperature is called a saturated solution.
→ Distillation: The process in which a liquid is converted into vapours by boiling it and the vapours so formed are condensed by cooling to give pure liquid is called distillation.
→ Hand-picking: The method of separating undesirable solid substances or impurities from useful solids by hand is known as handpicking.
→ Winnowing: When the particles of impurities are light or when light and heavy particles from a mixture then the winnowing method is used to separate them.
→ Threshing: The process of separating grains from the stalks is called threshing. In this method, we beat stalks to free the seeds.
→ Sieving: Sieving is a method in which smaller solid particles are separated from bigger and larger solid particles by passing through a sieve.
→ Sedimentation: In this process, the liquid mixture is placed undisturbed for some time. Solid heavy insoluble particles settle down and lighter particles float in the liquid.
→ Decantation: The process of transferring the liquid from the mixture without disturbing sediments is known as decantation.
→ Churning: The process of separation of lighter particles from a liquid mixture is churning.
→ Evaporation: Evaporation is a process in which liquid is converted into its vapours by heating.
→ Condensation: The process of converting water vapours into their liquid form is called condensation.
→ Filtrate: The clean liquid obtained during filtration is known as filtrate.
→ Residue: The sand and mud left on the filter paper is known as the residue.