Chapter 2 Is Matter Around Us Pure Class 9 Notes | EduRev

Created by: Sushil Solanki

Class 9 : Chapter 2 Is Matter Around Us Pure Class 9 Notes | EduRev

 Page 1


Chapter 2 Is Matter Around Us Pure? 
Substance – A pure form of matter that cannot be separated or broken down further by any physical process. E.g. sodium 
chloride cannot be separated into sodium and chlorine by physical processes, so it is a substance. But it can be separated 
from a salt solution by evaporation therefore, a salt solution is not a substance. 
E.g. of physical processes – Sieving, winnowing, evaporation, filtration, sublimation etc. 
Mixture – Made up of more than one type of substances that may or may not be separated by physical processes. 
Types of mixture: 
1. Homogenous mixtures – A type of mixture in which the constituent substances mix evenly throughout is known 
as homogenous mixture. E.g. a salt or sugar solution 
2. Heterogeneous mixtures – A kind of mixture in which the constituent substances do not mix evenly is known as 
heterogeneous mixture. E.g. Iron fillings mixed with salt, mixture of pebbles and sand, mixture of oil and water. 
 
Solution 
? Homogeneous mixture of two or more substances is called a solution. E.g. Air, salt or water solution, alloys etc. 
? Particle of solution are smaller than a nanometer (10
-9
m) and cannot be seen with naked eyes. 
? They cannot scatter a beam of light passing through them. 
? Solute particles cannot be separated by filtration; neither do they settle when left undisturbed. 
Alloys – Homogeneous mixtures of two or more metals that cannot be separated by physical processes. E.g. brass is an 
alloy of 30% zinc and 70% copper. 
 Solute – The component of a solution that gets dissolved into another component. Usually the one present in 
smaller amount. 
 Solvent – The component of a solution that is dissolves other substances. Usually the solvent is the one present in 
larger amount. 
E.g. In a sodium chloride solution, water is the solvent (present in larger amount) while sodium chloride is the solute. 
 
Concentration of a solution = Amount of solute 
            Amount of solution 
    OR 
         Amount of solute 
        Amount of solvent 
 
Methods of expressing concentration of a solution: 
1. Mass by mass percentage of a solution 
       = Mass of solute x 100 
 Mass of solution 
 
2. Mass by volume percentage of a solution 
      = Mass of solute x 100 
          Volume of solution 
 
 
Suspension 
? Heterogeneous mixture in which a solid is dispersed in a liquid. 
? Particles of suspension can be seen with our naked eyes. 
? Suspensions can scatter a beam of light and makes its path visible. Tyndall effect 
Page 2


Chapter 2 Is Matter Around Us Pure? 
Substance – A pure form of matter that cannot be separated or broken down further by any physical process. E.g. sodium 
chloride cannot be separated into sodium and chlorine by physical processes, so it is a substance. But it can be separated 
from a salt solution by evaporation therefore, a salt solution is not a substance. 
E.g. of physical processes – Sieving, winnowing, evaporation, filtration, sublimation etc. 
Mixture – Made up of more than one type of substances that may or may not be separated by physical processes. 
Types of mixture: 
1. Homogenous mixtures – A type of mixture in which the constituent substances mix evenly throughout is known 
as homogenous mixture. E.g. a salt or sugar solution 
2. Heterogeneous mixtures – A kind of mixture in which the constituent substances do not mix evenly is known as 
heterogeneous mixture. E.g. Iron fillings mixed with salt, mixture of pebbles and sand, mixture of oil and water. 
 
Solution 
? Homogeneous mixture of two or more substances is called a solution. E.g. Air, salt or water solution, alloys etc. 
? Particle of solution are smaller than a nanometer (10
-9
m) and cannot be seen with naked eyes. 
? They cannot scatter a beam of light passing through them. 
? Solute particles cannot be separated by filtration; neither do they settle when left undisturbed. 
Alloys – Homogeneous mixtures of two or more metals that cannot be separated by physical processes. E.g. brass is an 
alloy of 30% zinc and 70% copper. 
 Solute – The component of a solution that gets dissolved into another component. Usually the one present in 
smaller amount. 
 Solvent – The component of a solution that is dissolves other substances. Usually the solvent is the one present in 
larger amount. 
E.g. In a sodium chloride solution, water is the solvent (present in larger amount) while sodium chloride is the solute. 
 
Concentration of a solution = Amount of solute 
            Amount of solution 
    OR 
         Amount of solute 
        Amount of solvent 
 
Methods of expressing concentration of a solution: 
1. Mass by mass percentage of a solution 
       = Mass of solute x 100 
 Mass of solution 
 
2. Mass by volume percentage of a solution 
      = Mass of solute x 100 
          Volume of solution 
 
 
Suspension 
? Heterogeneous mixture in which a solid is dispersed in a liquid. 
? Particles of suspension can be seen with our naked eyes. 
? Suspensions can scatter a beam of light and makes its path visible. Tyndall effect 
? Salute particles settle down when left undisturbed or by filtration. 
? E.g. Sand in water, muddy water etc. 
 
 
 
Tyndall Effect – Scattering of light by a colloidal or suspension solution is known as tyndall effect. 
 
Colloidal Solutions 
? It is a heterogeneous mixture. 
? The particles of colloidal solution cannot be seen with our naked eyes. 
? Colloidal solutions can scatter a beam of light to show tyndall effect. 
? Particles of colloidal solutions cannot be separated by filtration or sedimentation. 
? The solutes in a colloidal solution are called the dispersed phase and the solvent is called the dispersion 
medium. 
? E.g. Fog, Milk, Shaving cream, smoke, cheese etc. 
 
Purification methods for Mixtures 
1. Evaporation  
The process of converting a liquid into vapors is known as evaporation. 
Volatile substance evaporates a lower temperature and can be separated from a mixture by heating. 
Volatile substance – A substance that evaporates easily on heating. E.g. kerosene, petrol, water etc. 
 
2. Centrifugation   
? Spinning of a mixture at very high speed is known as centrifugation. 
? A centrifuge is an instrument that is used for centrifugation. 
? Cream can be separated from milk by centrifugation. 
? Heavier substances in the mixture settles at the bottom while the lighter particles stay on the top. 
Application 
? Used in laboratories blood and urine tests. 
? Used in dairies to separate cream from milk. 
? Used in washing machines to dry clothes.  
 
 
Page 3


Chapter 2 Is Matter Around Us Pure? 
Substance – A pure form of matter that cannot be separated or broken down further by any physical process. E.g. sodium 
chloride cannot be separated into sodium and chlorine by physical processes, so it is a substance. But it can be separated 
from a salt solution by evaporation therefore, a salt solution is not a substance. 
E.g. of physical processes – Sieving, winnowing, evaporation, filtration, sublimation etc. 
Mixture – Made up of more than one type of substances that may or may not be separated by physical processes. 
Types of mixture: 
1. Homogenous mixtures – A type of mixture in which the constituent substances mix evenly throughout is known 
as homogenous mixture. E.g. a salt or sugar solution 
2. Heterogeneous mixtures – A kind of mixture in which the constituent substances do not mix evenly is known as 
heterogeneous mixture. E.g. Iron fillings mixed with salt, mixture of pebbles and sand, mixture of oil and water. 
 
Solution 
? Homogeneous mixture of two or more substances is called a solution. E.g. Air, salt or water solution, alloys etc. 
? Particle of solution are smaller than a nanometer (10
-9
m) and cannot be seen with naked eyes. 
? They cannot scatter a beam of light passing through them. 
? Solute particles cannot be separated by filtration; neither do they settle when left undisturbed. 
Alloys – Homogeneous mixtures of two or more metals that cannot be separated by physical processes. E.g. brass is an 
alloy of 30% zinc and 70% copper. 
 Solute – The component of a solution that gets dissolved into another component. Usually the one present in 
smaller amount. 
 Solvent – The component of a solution that is dissolves other substances. Usually the solvent is the one present in 
larger amount. 
E.g. In a sodium chloride solution, water is the solvent (present in larger amount) while sodium chloride is the solute. 
 
Concentration of a solution = Amount of solute 
            Amount of solution 
    OR 
         Amount of solute 
        Amount of solvent 
 
Methods of expressing concentration of a solution: 
1. Mass by mass percentage of a solution 
       = Mass of solute x 100 
 Mass of solution 
 
2. Mass by volume percentage of a solution 
      = Mass of solute x 100 
          Volume of solution 
 
 
Suspension 
? Heterogeneous mixture in which a solid is dispersed in a liquid. 
? Particles of suspension can be seen with our naked eyes. 
? Suspensions can scatter a beam of light and makes its path visible. Tyndall effect 
? Salute particles settle down when left undisturbed or by filtration. 
? E.g. Sand in water, muddy water etc. 
 
 
 
Tyndall Effect – Scattering of light by a colloidal or suspension solution is known as tyndall effect. 
 
Colloidal Solutions 
? It is a heterogeneous mixture. 
? The particles of colloidal solution cannot be seen with our naked eyes. 
? Colloidal solutions can scatter a beam of light to show tyndall effect. 
? Particles of colloidal solutions cannot be separated by filtration or sedimentation. 
? The solutes in a colloidal solution are called the dispersed phase and the solvent is called the dispersion 
medium. 
? E.g. Fog, Milk, Shaving cream, smoke, cheese etc. 
 
Purification methods for Mixtures 
1. Evaporation  
The process of converting a liquid into vapors is known as evaporation. 
Volatile substance evaporates a lower temperature and can be separated from a mixture by heating. 
Volatile substance – A substance that evaporates easily on heating. E.g. kerosene, petrol, water etc. 
 
2. Centrifugation   
? Spinning of a mixture at very high speed is known as centrifugation. 
? A centrifuge is an instrument that is used for centrifugation. 
? Cream can be separated from milk by centrifugation. 
? Heavier substances in the mixture settles at the bottom while the lighter particles stay on the top. 
Application 
? Used in laboratories blood and urine tests. 
? Used in dairies to separate cream from milk. 
? Used in washing machines to dry clothes.  
 
 
3. Decantation  
It is used to separate two immiscible liquids 
Immiscible liquids – Liquids that do not dissolve with each other and one forms a clearly visible layer over the 
other. E.g. Oil and water. 
 
   Fig. Decantation 
Process  
? The two liquids are allowed to stand without disturbance unless they form two clear visible layers. 
? A beaker is kept under the funnel and the stop cock is opened slowly. 
? The water starts moving into the beaker. 
? The stopcock is closed as soon as all the water has moved in the beaker. 
? The water gets collected in the beaker while the kerosene is separated in the separating funnel. 
 
4. Sublimation 
A process in which a solid such as camphor or ammonium chloride directly converts to gaseous state on heating without 
becoming liquid is known as sublimation. 
Page 4


Chapter 2 Is Matter Around Us Pure? 
Substance – A pure form of matter that cannot be separated or broken down further by any physical process. E.g. sodium 
chloride cannot be separated into sodium and chlorine by physical processes, so it is a substance. But it can be separated 
from a salt solution by evaporation therefore, a salt solution is not a substance. 
E.g. of physical processes – Sieving, winnowing, evaporation, filtration, sublimation etc. 
Mixture – Made up of more than one type of substances that may or may not be separated by physical processes. 
Types of mixture: 
1. Homogenous mixtures – A type of mixture in which the constituent substances mix evenly throughout is known 
as homogenous mixture. E.g. a salt or sugar solution 
2. Heterogeneous mixtures – A kind of mixture in which the constituent substances do not mix evenly is known as 
heterogeneous mixture. E.g. Iron fillings mixed with salt, mixture of pebbles and sand, mixture of oil and water. 
 
Solution 
? Homogeneous mixture of two or more substances is called a solution. E.g. Air, salt or water solution, alloys etc. 
? Particle of solution are smaller than a nanometer (10
-9
m) and cannot be seen with naked eyes. 
? They cannot scatter a beam of light passing through them. 
? Solute particles cannot be separated by filtration; neither do they settle when left undisturbed. 
Alloys – Homogeneous mixtures of two or more metals that cannot be separated by physical processes. E.g. brass is an 
alloy of 30% zinc and 70% copper. 
 Solute – The component of a solution that gets dissolved into another component. Usually the one present in 
smaller amount. 
 Solvent – The component of a solution that is dissolves other substances. Usually the solvent is the one present in 
larger amount. 
E.g. In a sodium chloride solution, water is the solvent (present in larger amount) while sodium chloride is the solute. 
 
Concentration of a solution = Amount of solute 
            Amount of solution 
    OR 
         Amount of solute 
        Amount of solvent 
 
Methods of expressing concentration of a solution: 
1. Mass by mass percentage of a solution 
       = Mass of solute x 100 
 Mass of solution 
 
2. Mass by volume percentage of a solution 
      = Mass of solute x 100 
          Volume of solution 
 
 
Suspension 
? Heterogeneous mixture in which a solid is dispersed in a liquid. 
? Particles of suspension can be seen with our naked eyes. 
? Suspensions can scatter a beam of light and makes its path visible. Tyndall effect 
? Salute particles settle down when left undisturbed or by filtration. 
? E.g. Sand in water, muddy water etc. 
 
 
 
Tyndall Effect – Scattering of light by a colloidal or suspension solution is known as tyndall effect. 
 
Colloidal Solutions 
? It is a heterogeneous mixture. 
? The particles of colloidal solution cannot be seen with our naked eyes. 
? Colloidal solutions can scatter a beam of light to show tyndall effect. 
? Particles of colloidal solutions cannot be separated by filtration or sedimentation. 
? The solutes in a colloidal solution are called the dispersed phase and the solvent is called the dispersion 
medium. 
? E.g. Fog, Milk, Shaving cream, smoke, cheese etc. 
 
Purification methods for Mixtures 
1. Evaporation  
The process of converting a liquid into vapors is known as evaporation. 
Volatile substance evaporates a lower temperature and can be separated from a mixture by heating. 
Volatile substance – A substance that evaporates easily on heating. E.g. kerosene, petrol, water etc. 
 
2. Centrifugation   
? Spinning of a mixture at very high speed is known as centrifugation. 
? A centrifuge is an instrument that is used for centrifugation. 
? Cream can be separated from milk by centrifugation. 
? Heavier substances in the mixture settles at the bottom while the lighter particles stay on the top. 
Application 
? Used in laboratories blood and urine tests. 
? Used in dairies to separate cream from milk. 
? Used in washing machines to dry clothes.  
 
 
3. Decantation  
It is used to separate two immiscible liquids 
Immiscible liquids – Liquids that do not dissolve with each other and one forms a clearly visible layer over the 
other. E.g. Oil and water. 
 
   Fig. Decantation 
Process  
? The two liquids are allowed to stand without disturbance unless they form two clear visible layers. 
? A beaker is kept under the funnel and the stop cock is opened slowly. 
? The water starts moving into the beaker. 
? The stopcock is closed as soon as all the water has moved in the beaker. 
? The water gets collected in the beaker while the kerosene is separated in the separating funnel. 
 
4. Sublimation 
A process in which a solid such as camphor or ammonium chloride directly converts to gaseous state on heating without 
becoming liquid is known as sublimation. 
`   Fig. Separation of ammonium chloride from a mixture. 
 
The vapors of ammonium chloride stick to the walls of the inverted funnel when the mixture of ammonium chloride and 
salt is heated in the above setup or experiment while the salt remains in the china dish. 
 
 
5. Chromatography 
The process of separation of the components in a mixture such as dye on the basis of their solubility of affinity with the 
solvent. 
 
 
 
 
 
 
               
        Fig. Chromatography setup 
 
Process 
? Dye or ink in loaded on a point at the bottom center of a paper strip. 
? A jar is filled with an appropriate solvent (water in this case) 
? The strip is hangs in the jar such that it just touches the solvent present in the jar. 
? The water will move up the filter paper and the components present in the dye will move along with it depending 
upon their affinity (attachment) with water or the filter paper. 
? Since, all the components have different affinities they move at different rates and are collected at different 
regions on the filter paper.  
Applications 
? To separate colors from a dye 
? To separate pigments a leaf 
? To separate drugs from blood. 
 
 
6. Distillation 
 
? It is used in the separation of miscible liquids, which do not decompose on boiling and have sufficiently 
different boiling points. 
? The mixture is first heated. 
? The substance with low boiling point evaporates first. 
? The vapors are collected and cooled down using cold water to its liquid state again. 
? The liquid state is collected in a beaker. 
? The experimental setup for distillation is given below. 
 
Spot of ink 
Various components 
of the dye separated 
Page 5


Chapter 2 Is Matter Around Us Pure? 
Substance – A pure form of matter that cannot be separated or broken down further by any physical process. E.g. sodium 
chloride cannot be separated into sodium and chlorine by physical processes, so it is a substance. But it can be separated 
from a salt solution by evaporation therefore, a salt solution is not a substance. 
E.g. of physical processes – Sieving, winnowing, evaporation, filtration, sublimation etc. 
Mixture – Made up of more than one type of substances that may or may not be separated by physical processes. 
Types of mixture: 
1. Homogenous mixtures – A type of mixture in which the constituent substances mix evenly throughout is known 
as homogenous mixture. E.g. a salt or sugar solution 
2. Heterogeneous mixtures – A kind of mixture in which the constituent substances do not mix evenly is known as 
heterogeneous mixture. E.g. Iron fillings mixed with salt, mixture of pebbles and sand, mixture of oil and water. 
 
Solution 
? Homogeneous mixture of two or more substances is called a solution. E.g. Air, salt or water solution, alloys etc. 
? Particle of solution are smaller than a nanometer (10
-9
m) and cannot be seen with naked eyes. 
? They cannot scatter a beam of light passing through them. 
? Solute particles cannot be separated by filtration; neither do they settle when left undisturbed. 
Alloys – Homogeneous mixtures of two or more metals that cannot be separated by physical processes. E.g. brass is an 
alloy of 30% zinc and 70% copper. 
 Solute – The component of a solution that gets dissolved into another component. Usually the one present in 
smaller amount. 
 Solvent – The component of a solution that is dissolves other substances. Usually the solvent is the one present in 
larger amount. 
E.g. In a sodium chloride solution, water is the solvent (present in larger amount) while sodium chloride is the solute. 
 
Concentration of a solution = Amount of solute 
            Amount of solution 
    OR 
         Amount of solute 
        Amount of solvent 
 
Methods of expressing concentration of a solution: 
1. Mass by mass percentage of a solution 
       = Mass of solute x 100 
 Mass of solution 
 
2. Mass by volume percentage of a solution 
      = Mass of solute x 100 
          Volume of solution 
 
 
Suspension 
? Heterogeneous mixture in which a solid is dispersed in a liquid. 
? Particles of suspension can be seen with our naked eyes. 
? Suspensions can scatter a beam of light and makes its path visible. Tyndall effect 
? Salute particles settle down when left undisturbed or by filtration. 
? E.g. Sand in water, muddy water etc. 
 
 
 
Tyndall Effect – Scattering of light by a colloidal or suspension solution is known as tyndall effect. 
 
Colloidal Solutions 
? It is a heterogeneous mixture. 
? The particles of colloidal solution cannot be seen with our naked eyes. 
? Colloidal solutions can scatter a beam of light to show tyndall effect. 
? Particles of colloidal solutions cannot be separated by filtration or sedimentation. 
? The solutes in a colloidal solution are called the dispersed phase and the solvent is called the dispersion 
medium. 
? E.g. Fog, Milk, Shaving cream, smoke, cheese etc. 
 
Purification methods for Mixtures 
1. Evaporation  
The process of converting a liquid into vapors is known as evaporation. 
Volatile substance evaporates a lower temperature and can be separated from a mixture by heating. 
Volatile substance – A substance that evaporates easily on heating. E.g. kerosene, petrol, water etc. 
 
2. Centrifugation   
? Spinning of a mixture at very high speed is known as centrifugation. 
? A centrifuge is an instrument that is used for centrifugation. 
? Cream can be separated from milk by centrifugation. 
? Heavier substances in the mixture settles at the bottom while the lighter particles stay on the top. 
Application 
? Used in laboratories blood and urine tests. 
? Used in dairies to separate cream from milk. 
? Used in washing machines to dry clothes.  
 
 
3. Decantation  
It is used to separate two immiscible liquids 
Immiscible liquids – Liquids that do not dissolve with each other and one forms a clearly visible layer over the 
other. E.g. Oil and water. 
 
   Fig. Decantation 
Process  
? The two liquids are allowed to stand without disturbance unless they form two clear visible layers. 
? A beaker is kept under the funnel and the stop cock is opened slowly. 
? The water starts moving into the beaker. 
? The stopcock is closed as soon as all the water has moved in the beaker. 
? The water gets collected in the beaker while the kerosene is separated in the separating funnel. 
 
4. Sublimation 
A process in which a solid such as camphor or ammonium chloride directly converts to gaseous state on heating without 
becoming liquid is known as sublimation. 
`   Fig. Separation of ammonium chloride from a mixture. 
 
The vapors of ammonium chloride stick to the walls of the inverted funnel when the mixture of ammonium chloride and 
salt is heated in the above setup or experiment while the salt remains in the china dish. 
 
 
5. Chromatography 
The process of separation of the components in a mixture such as dye on the basis of their solubility of affinity with the 
solvent. 
 
 
 
 
 
 
               
        Fig. Chromatography setup 
 
Process 
? Dye or ink in loaded on a point at the bottom center of a paper strip. 
? A jar is filled with an appropriate solvent (water in this case) 
? The strip is hangs in the jar such that it just touches the solvent present in the jar. 
? The water will move up the filter paper and the components present in the dye will move along with it depending 
upon their affinity (attachment) with water or the filter paper. 
? Since, all the components have different affinities they move at different rates and are collected at different 
regions on the filter paper.  
Applications 
? To separate colors from a dye 
? To separate pigments a leaf 
? To separate drugs from blood. 
 
 
6. Distillation 
 
? It is used in the separation of miscible liquids, which do not decompose on boiling and have sufficiently 
different boiling points. 
? The mixture is first heated. 
? The substance with low boiling point evaporates first. 
? The vapors are collected and cooled down using cold water to its liquid state again. 
? The liquid state is collected in a beaker. 
? The experimental setup for distillation is given below. 
 
Spot of ink 
Various components 
of the dye separated 
                    Fig. Distillation for separation of acetone from its solution. 
 
7. Fractional Distillation 
                   Principle 
? It uses the same principle as that of distillation 
? The only difference is that it is used for the separation of two or more miscible liquids, which do not 
decompose on boiling and the difference in their boiling point is less than 25K 
? A fractionating column is attached between the distillation flask and the condenser. 
? The fractionating column is filled with beads that provide surface area for vapors to cool and condense 
repeatedly.  
Applications: 
? It is used in refining of petroleum. 
? It is used for separation of gases from air. 
 
                           Fig. Setup for fractional distillation 
 
Separation of gases from Air through fractional distillation 
Air is a homogeneous mixture of various gases. 
Principle 
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