Ch-2 - Is Matter Around Us Pure, Class 9, Science Chapter Notes PDF Download

 Page 1


 
 
IS MATTER AROUND US PURE
 
Matter  
Anything that occupies space and has a mass is called matter. 
In other words we can say that matter is anything which we 
can feel, touch and see e.g. iron, wood, rock sugar, sand, 
water, milk, oil, air, oxygen etc. 
 
Classification Of Matter
Physical State Chemical State
Solids Liquids Gases Elements Compounds Mixtures
 
 
Chemical State 
 
Elements 
Robert Boyle was the first scientist to use the term element in 
1661. 
An element is a substance, which cannot be broken down into 
two or more simpler substances by simple physical methods or 
by chemical reactions. An element consists of only one kind of 
atoms that are having same atomic number, e.g. hydrogen, 
nitrogen, iron, gold etc. Elements may be solids, liquids or 
gases. Hydrogen is the lightest element. 
 
Total number of elements  118 
Elements occur in nature  92 
Elements artificially prepared 26 
 
3 elements are recently discovered. So, total number reaches 
to 118. 
 
Elements Can Be Normally Divided As:- 
Metals, non metals and metalloids. 
 
Properties Of Elements 
 
H  Molecules
2
O  Molecules
2 
 
(i) An element is a pure substance. 
(ii) An element cannot be broken down into two or more 
simpler substances. 
(iii) An element combines with other elements to form 
compounds. 
(iv) An element may exist as a solid, liquid or gas. 
 
Properties Of Metals 
(i) They have luster (shine). 
(ii) They conduct heat and electricity. 
(iii) They are malleable (can be hammered into thin sheets). 
(iv) They are ductile (can be drawn into wires). 
 
(v) They are sonorous (make sound). 
(vi) They have generally golden yellow or silvery grey color. 
(vii) They are solids, only mercury is liquid. 
 
Properties Of Non Metals 
(i) They are non malleable. 
(ii) They are non ductile. 
(iii) They are non sonorous. 
(iv) They are non lustrous. 
(v) They are poor conductors of heat and electricity. 
(vi) They show a variety of colors. 
(vii) They exist in all the three states i.e., solids, liquids and 
gas. 
(viii) They are generally soft. 
 
Metalloids 
Metalloids have intermediate properties between those of 
metals and non metals. Examples are boron, silicon, 
germanium, arsenic etc.. 
 
Compounds 
A compound is a substance, which consists of two or more 
elements chemically combined with one another in a fixed 
proportion by mass. For example water. It is a compound 
made up of two elements hydrogen and oxygen, which are 
chemically combined in a fixed proportion of 1 : 8 by mass. 
 
Atomic weight hydrogen = 1 
Atomic weight oxygen = 16 
Their ratio in H
2
O = 2 : 16  =>  1 : 8 
 
Properties Of Compound 
 
CO  Molecules Co  Molecules
2 
 
(i) Compound cannot be separated into its components by 
physical methods. 
(ii) The properties of compound are entirely different from 
those of its constituent elements. 
(iii) Energy in the form of heat and light is usually given out or 
absorbed during the preparation of compounds. 
(iv) The composition of compound is fixed. That means the 
constituents of compound are present in fixed proportion 
by weight. 
(v) A compound is homogeneous substance. 
(vi) A compound has a fixed melting and boiling point. 
 
Mixtures 
A mixture consists of more than one substance (elements or 
compounds) in any proportion by mass. A mixture can be 
separated into two or more simpler substances by physical 
means, e.g. air is a mixture of gases like oxygen, nitrogen, 
 
Page 2


 
 
IS MATTER AROUND US PURE
 
Matter  
Anything that occupies space and has a mass is called matter. 
In other words we can say that matter is anything which we 
can feel, touch and see e.g. iron, wood, rock sugar, sand, 
water, milk, oil, air, oxygen etc. 
 
Classification Of Matter
Physical State Chemical State
Solids Liquids Gases Elements Compounds Mixtures
 
 
Chemical State 
 
Elements 
Robert Boyle was the first scientist to use the term element in 
1661. 
An element is a substance, which cannot be broken down into 
two or more simpler substances by simple physical methods or 
by chemical reactions. An element consists of only one kind of 
atoms that are having same atomic number, e.g. hydrogen, 
nitrogen, iron, gold etc. Elements may be solids, liquids or 
gases. Hydrogen is the lightest element. 
 
Total number of elements  118 
Elements occur in nature  92 
Elements artificially prepared 26 
 
3 elements are recently discovered. So, total number reaches 
to 118. 
 
Elements Can Be Normally Divided As:- 
Metals, non metals and metalloids. 
 
Properties Of Elements 
 
H  Molecules
2
O  Molecules
2 
 
(i) An element is a pure substance. 
(ii) An element cannot be broken down into two or more 
simpler substances. 
(iii) An element combines with other elements to form 
compounds. 
(iv) An element may exist as a solid, liquid or gas. 
 
Properties Of Metals 
(i) They have luster (shine). 
(ii) They conduct heat and electricity. 
(iii) They are malleable (can be hammered into thin sheets). 
(iv) They are ductile (can be drawn into wires). 
 
(v) They are sonorous (make sound). 
(vi) They have generally golden yellow or silvery grey color. 
(vii) They are solids, only mercury is liquid. 
 
Properties Of Non Metals 
(i) They are non malleable. 
(ii) They are non ductile. 
(iii) They are non sonorous. 
(iv) They are non lustrous. 
(v) They are poor conductors of heat and electricity. 
(vi) They show a variety of colors. 
(vii) They exist in all the three states i.e., solids, liquids and 
gas. 
(viii) They are generally soft. 
 
Metalloids 
Metalloids have intermediate properties between those of 
metals and non metals. Examples are boron, silicon, 
germanium, arsenic etc.. 
 
Compounds 
A compound is a substance, which consists of two or more 
elements chemically combined with one another in a fixed 
proportion by mass. For example water. It is a compound 
made up of two elements hydrogen and oxygen, which are 
chemically combined in a fixed proportion of 1 : 8 by mass. 
 
Atomic weight hydrogen = 1 
Atomic weight oxygen = 16 
Their ratio in H
2
O = 2 : 16  =>  1 : 8 
 
Properties Of Compound 
 
CO  Molecules Co  Molecules
2 
 
(i) Compound cannot be separated into its components by 
physical methods. 
(ii) The properties of compound are entirely different from 
those of its constituent elements. 
(iii) Energy in the form of heat and light is usually given out or 
absorbed during the preparation of compounds. 
(iv) The composition of compound is fixed. That means the 
constituents of compound are present in fixed proportion 
by weight. 
(v) A compound is homogeneous substance. 
(vi) A compound has a fixed melting and boiling point. 
 
Mixtures 
A mixture consists of more than one substance (elements or 
compounds) in any proportion by mass. A mixture can be 
separated into two or more simpler substances by physical 
means, e.g. air is a mixture of gases like oxygen, nitrogen, 
 
 
carbon dioxide and water vapours etc. These gases are not 
chemically combined with one another. 
 
Types Of Mixture 
 
Types Of Mixture
Homogeneous Heterogenouse
Mixtures Mixtures
 
(Solutions, Colloids)        (Suspensions) 
 
Homogeneous Mixture 
It has a uniform composition throughout its mass. It has no 
visible boundaries of separation between its various 
constituents. A homogeneous mixture is also called solution. 
e.g. a mixture of sugar in water. All parts of sugar solution 
have same sugar water composition. There is no visible 
boundary of separation between sugar and water. 
 
Heterogeneous Mixture 
It does not have uniform composition throughout its mass. It 
has visible boundaries of separation between the various 
constituents, e.g. a mixture of sugar and sand. Different parts 
of this mixture will have different sugar-sand composition. 
Sugar and sand can be visibly separated from each other or 
from the mixture. 
 
Properties Of Mixture 
(i) A mixture can be separated into its constituents by simple 
physical methods. 
(ii) A mixture shows the properties of all constituents present 
in it. 
(iii) The constituents of a mixture are not in a fixed proportion 
by weight. 
(iv) Energy is usually neither given out not absorbed in the 
preparation of mixture. 
(v) A mixture does not have a definite melting and boiling 
point due to the presence of unequal amount of 
constituents. 
(vi) A mixture is usually heterogeneous. 
 
A mixture consists of two things: - 
 
Solute 
The substance present in smaller amount or the substance 
which is dissolved in a liquid to make solution is called solute. 
 
Solvent 
The substance present in larger amount or the substance in 
which solute is dissolved is called solvent, e.g. sugar solution 
is made by dissolving sugar in water. So, in sugar solution, 
sugar is solute and water is solvent. 
 
Solution 
A homogeneous mixture of two or more substance is called 
solution. Substance could be solids, liquids or gases. We 
cannot distinguish the solute particles from the solvent 
molecule even by using a microscope. Usually we think of a 
solution as a liquid that contains either a solid liquid or a gas 
dissolved in it. But we can also have solid solutions (alloys), 
gaseous solutions (air). 
 
Properties Of Solution 
(i) A solution is a homogeneous mixture. 
(ii) The size of solute particles in solution is extremely small 
(diameter=10
-6
cm).  
(iii) A solution is very stable i.e., the solute particles do not 
settle down on keeping.   
(iv) A true solution does not scatter light. 
(v) A solution cannot be filtered with a filter paper. 
 
Concentration Of Solution 
Depending upon the amount of solute present in a solution, it 
can be called dilute, concentrated or a saturated solution. 
 
Concentration of solution is either the amount of solute 
present in given mass or volume of solution or the amount of 
solute dissolved in a given mass of or volume of the solvent. 
Or 
Concentration of solution is the amount of solute present in a 
given quantity of solution. The Percentage Method is the most 
common way of expressing the concentration of solution. 
Concentration of solution is equal to mass of solute in grams 
present in 100 grams of solution. 
 
For example, 10 percent solution of common salt means, 10 
grams of common salt present in 100 grams of water. 
 
100 gram salt solution = 10 grams of salt + 90 grams of water 
 
Concentration Of Solution = 100
Solution Of Mass
Solute Of Mass
× 
Where 
Mass of solution = Mass Of Solute  +  Mass Of Solvent 
 
Example 
For a 10 % salt solution we will say  
Mass of solute (salt) = 10 grams 
Mass of solvent (water) = 90 grams 
Concentration Of Solution = 100
90 10
10
×
+
 = 100
100
10
× =10% 
 
Saturated Solution 
When at a particular temperature as maximum possible solute 
is dissolved in a solution as it is capable of, then it is called 
saturated solution. 
 
Unsaturated Solution 
When the amount of solute in a solution is less than its 
saturation level. Or at any given temperature if the amount of 
solute can be increased again and again the solution is called 
unsaturated solution.  
 
Solubility 
Solubility is defined as the maximum amount of solute, which 
is required to dissolve in the solvent at a given temperature to 
make a saturated solution. For example if at 40
0 
c, 36.5 gm of 
sodium chloride is required to dissolve in water to make a 
saturated solution then it will be said that, the solubility of 
sodium chloride at 40
0
 c is 36.5 gm. 
 
Aqueous Solutions 
The solutions made by dissolving various solutes in water are 
called aqueous solutions. Water is a universal solvent. 
 
Non-Aqueous Solutions 
The solutions made by dissolving solutes in organic liquids or 
solvents other than water are called non-aqueous solutions. 
 
Suspension 
A suspension is a heterogeneous mixture in which the small 
particles of solids are spread throughout in a liquid without 
dissolving in it. 
 
Page 3


 
 
IS MATTER AROUND US PURE
 
Matter  
Anything that occupies space and has a mass is called matter. 
In other words we can say that matter is anything which we 
can feel, touch and see e.g. iron, wood, rock sugar, sand, 
water, milk, oil, air, oxygen etc. 
 
Classification Of Matter
Physical State Chemical State
Solids Liquids Gases Elements Compounds Mixtures
 
 
Chemical State 
 
Elements 
Robert Boyle was the first scientist to use the term element in 
1661. 
An element is a substance, which cannot be broken down into 
two or more simpler substances by simple physical methods or 
by chemical reactions. An element consists of only one kind of 
atoms that are having same atomic number, e.g. hydrogen, 
nitrogen, iron, gold etc. Elements may be solids, liquids or 
gases. Hydrogen is the lightest element. 
 
Total number of elements  118 
Elements occur in nature  92 
Elements artificially prepared 26 
 
3 elements are recently discovered. So, total number reaches 
to 118. 
 
Elements Can Be Normally Divided As:- 
Metals, non metals and metalloids. 
 
Properties Of Elements 
 
H  Molecules
2
O  Molecules
2 
 
(i) An element is a pure substance. 
(ii) An element cannot be broken down into two or more 
simpler substances. 
(iii) An element combines with other elements to form 
compounds. 
(iv) An element may exist as a solid, liquid or gas. 
 
Properties Of Metals 
(i) They have luster (shine). 
(ii) They conduct heat and electricity. 
(iii) They are malleable (can be hammered into thin sheets). 
(iv) They are ductile (can be drawn into wires). 
 
(v) They are sonorous (make sound). 
(vi) They have generally golden yellow or silvery grey color. 
(vii) They are solids, only mercury is liquid. 
 
Properties Of Non Metals 
(i) They are non malleable. 
(ii) They are non ductile. 
(iii) They are non sonorous. 
(iv) They are non lustrous. 
(v) They are poor conductors of heat and electricity. 
(vi) They show a variety of colors. 
(vii) They exist in all the three states i.e., solids, liquids and 
gas. 
(viii) They are generally soft. 
 
Metalloids 
Metalloids have intermediate properties between those of 
metals and non metals. Examples are boron, silicon, 
germanium, arsenic etc.. 
 
Compounds 
A compound is a substance, which consists of two or more 
elements chemically combined with one another in a fixed 
proportion by mass. For example water. It is a compound 
made up of two elements hydrogen and oxygen, which are 
chemically combined in a fixed proportion of 1 : 8 by mass. 
 
Atomic weight hydrogen = 1 
Atomic weight oxygen = 16 
Their ratio in H
2
O = 2 : 16  =>  1 : 8 
 
Properties Of Compound 
 
CO  Molecules Co  Molecules
2 
 
(i) Compound cannot be separated into its components by 
physical methods. 
(ii) The properties of compound are entirely different from 
those of its constituent elements. 
(iii) Energy in the form of heat and light is usually given out or 
absorbed during the preparation of compounds. 
(iv) The composition of compound is fixed. That means the 
constituents of compound are present in fixed proportion 
by weight. 
(v) A compound is homogeneous substance. 
(vi) A compound has a fixed melting and boiling point. 
 
Mixtures 
A mixture consists of more than one substance (elements or 
compounds) in any proportion by mass. A mixture can be 
separated into two or more simpler substances by physical 
means, e.g. air is a mixture of gases like oxygen, nitrogen, 
 
 
carbon dioxide and water vapours etc. These gases are not 
chemically combined with one another. 
 
Types Of Mixture 
 
Types Of Mixture
Homogeneous Heterogenouse
Mixtures Mixtures
 
(Solutions, Colloids)        (Suspensions) 
 
Homogeneous Mixture 
It has a uniform composition throughout its mass. It has no 
visible boundaries of separation between its various 
constituents. A homogeneous mixture is also called solution. 
e.g. a mixture of sugar in water. All parts of sugar solution 
have same sugar water composition. There is no visible 
boundary of separation between sugar and water. 
 
Heterogeneous Mixture 
It does not have uniform composition throughout its mass. It 
has visible boundaries of separation between the various 
constituents, e.g. a mixture of sugar and sand. Different parts 
of this mixture will have different sugar-sand composition. 
Sugar and sand can be visibly separated from each other or 
from the mixture. 
 
Properties Of Mixture 
(i) A mixture can be separated into its constituents by simple 
physical methods. 
(ii) A mixture shows the properties of all constituents present 
in it. 
(iii) The constituents of a mixture are not in a fixed proportion 
by weight. 
(iv) Energy is usually neither given out not absorbed in the 
preparation of mixture. 
(v) A mixture does not have a definite melting and boiling 
point due to the presence of unequal amount of 
constituents. 
(vi) A mixture is usually heterogeneous. 
 
A mixture consists of two things: - 
 
Solute 
The substance present in smaller amount or the substance 
which is dissolved in a liquid to make solution is called solute. 
 
Solvent 
The substance present in larger amount or the substance in 
which solute is dissolved is called solvent, e.g. sugar solution 
is made by dissolving sugar in water. So, in sugar solution, 
sugar is solute and water is solvent. 
 
Solution 
A homogeneous mixture of two or more substance is called 
solution. Substance could be solids, liquids or gases. We 
cannot distinguish the solute particles from the solvent 
molecule even by using a microscope. Usually we think of a 
solution as a liquid that contains either a solid liquid or a gas 
dissolved in it. But we can also have solid solutions (alloys), 
gaseous solutions (air). 
 
Properties Of Solution 
(i) A solution is a homogeneous mixture. 
(ii) The size of solute particles in solution is extremely small 
(diameter=10
-6
cm).  
(iii) A solution is very stable i.e., the solute particles do not 
settle down on keeping.   
(iv) A true solution does not scatter light. 
(v) A solution cannot be filtered with a filter paper. 
 
Concentration Of Solution 
Depending upon the amount of solute present in a solution, it 
can be called dilute, concentrated or a saturated solution. 
 
Concentration of solution is either the amount of solute 
present in given mass or volume of solution or the amount of 
solute dissolved in a given mass of or volume of the solvent. 
Or 
Concentration of solution is the amount of solute present in a 
given quantity of solution. The Percentage Method is the most 
common way of expressing the concentration of solution. 
Concentration of solution is equal to mass of solute in grams 
present in 100 grams of solution. 
 
For example, 10 percent solution of common salt means, 10 
grams of common salt present in 100 grams of water. 
 
100 gram salt solution = 10 grams of salt + 90 grams of water 
 
Concentration Of Solution = 100
Solution Of Mass
Solute Of Mass
× 
Where 
Mass of solution = Mass Of Solute  +  Mass Of Solvent 
 
Example 
For a 10 % salt solution we will say  
Mass of solute (salt) = 10 grams 
Mass of solvent (water) = 90 grams 
Concentration Of Solution = 100
90 10
10
×
+
 = 100
100
10
× =10% 
 
Saturated Solution 
When at a particular temperature as maximum possible solute 
is dissolved in a solution as it is capable of, then it is called 
saturated solution. 
 
Unsaturated Solution 
When the amount of solute in a solution is less than its 
saturation level. Or at any given temperature if the amount of 
solute can be increased again and again the solution is called 
unsaturated solution.  
 
Solubility 
Solubility is defined as the maximum amount of solute, which 
is required to dissolve in the solvent at a given temperature to 
make a saturated solution. For example if at 40
0 
c, 36.5 gm of 
sodium chloride is required to dissolve in water to make a 
saturated solution then it will be said that, the solubility of 
sodium chloride at 40
0
 c is 36.5 gm. 
 
Aqueous Solutions 
The solutions made by dissolving various solutes in water are 
called aqueous solutions. Water is a universal solvent. 
 
Non-Aqueous Solutions 
The solutions made by dissolving solutes in organic liquids or 
solvents other than water are called non-aqueous solutions. 
 
Suspension 
A suspension is a heterogeneous mixture in which the small 
particles of solids are spread throughout in a liquid without 
dissolving in it. 
 
 
Properties Of Suspension 
(i) A suspension is a heterogeneous mixture. 
(ii) Size of solute particles in suspension is quite large. The 
size is larger than 10
-5
cm in diameters. 
(iii) The particles of a suspension can be seen easily. 
(iv) The particles of a suspension do not pass through a filter 
paper. So, a suspension can be separated by filtration. 
(v) Suspension particles are unstable. They settle down after 
some time. 
(vi) A suspension scatters beam of light passing through it, 
e.g. chalk-water mixture, paint, sand, water mixture, 
flour-water mixture, muddy water. Muddy water is a 
suspension of soil particles in water; paint is a suspension 
of colored substance in various liquids. 
 
Colloids 
Colloids are a kind of solution in which the size of the solute 
particles is bigger than that of a true solution, but smaller than 
that of a suspension. 
 
Properties Of Colloids 
(i) A colloid appears to be homogeneous, but actually it is 
heterogeneous. 
(ii) The size of the particles in a colloid is bigger than those in 
a true solution, but smaller than those of suspension. It is 
between 10
-7
 and 10
-5 
in diameter.      
(iii) Particles of colloid can pass through a filter paper. 
(iv) Colloids are quite stable. 
(v) A colloid scatters a beam of light, e.g. starch solution, 
milk, ink, blood, soap solution, toothpaste, and mist. Mist 
is a solution of water vapors suspended in air. 
 
Tyndall Effect 
The scattering of light by colloidal particles is called Tyndall 
Effect. The path of light inside a colloidal becomes visible 
because the solute particles in a colloidal solution are big 
enough to scatter or disperse the light rays falling on them in 
all directions. 
 
Separating Components Of A Mixture 
Different methods of separation are used to get individual 
components from a mixture. Separation makes it possible to 
study and use the individual components of a mixture. 
 
Obtaining Coloured Component From A Blue Black Ink 
It is done by Evaporation. 
By this process a volatile component can be separated from its 
non volatile solute. 
 
Separating Cream From Milk 
It is done by Centrifugation. 
The principle of this process is that the denser particles are 
forced to the bottom and the lighter particles stay at the top 
when spun rapidly. 
 
 
Separating A Mixture Of Two Immiscible Liquids 
It is done by Separating Funnel. 
The principle of this process is that immiscible liquids separate 
out in layers depending upon their densities. 
                  
Separating A Mixture Of Salt And Ammonium Chloride 
It is done by Sublimation. 
This process is done to separate a sublimable volatile 
component from a non sublimable impurity. 
       
Separating A Mixture Of Colors Of A Dye 
It is done by Chromatogarphy. 
It is a technique used to separate those solutes that dissolve 
in the same solvent. 
 
 
Page 4


 
 
IS MATTER AROUND US PURE
 
Matter  
Anything that occupies space and has a mass is called matter. 
In other words we can say that matter is anything which we 
can feel, touch and see e.g. iron, wood, rock sugar, sand, 
water, milk, oil, air, oxygen etc. 
 
Classification Of Matter
Physical State Chemical State
Solids Liquids Gases Elements Compounds Mixtures
 
 
Chemical State 
 
Elements 
Robert Boyle was the first scientist to use the term element in 
1661. 
An element is a substance, which cannot be broken down into 
two or more simpler substances by simple physical methods or 
by chemical reactions. An element consists of only one kind of 
atoms that are having same atomic number, e.g. hydrogen, 
nitrogen, iron, gold etc. Elements may be solids, liquids or 
gases. Hydrogen is the lightest element. 
 
Total number of elements  118 
Elements occur in nature  92 
Elements artificially prepared 26 
 
3 elements are recently discovered. So, total number reaches 
to 118. 
 
Elements Can Be Normally Divided As:- 
Metals, non metals and metalloids. 
 
Properties Of Elements 
 
H  Molecules
2
O  Molecules
2 
 
(i) An element is a pure substance. 
(ii) An element cannot be broken down into two or more 
simpler substances. 
(iii) An element combines with other elements to form 
compounds. 
(iv) An element may exist as a solid, liquid or gas. 
 
Properties Of Metals 
(i) They have luster (shine). 
(ii) They conduct heat and electricity. 
(iii) They are malleable (can be hammered into thin sheets). 
(iv) They are ductile (can be drawn into wires). 
 
(v) They are sonorous (make sound). 
(vi) They have generally golden yellow or silvery grey color. 
(vii) They are solids, only mercury is liquid. 
 
Properties Of Non Metals 
(i) They are non malleable. 
(ii) They are non ductile. 
(iii) They are non sonorous. 
(iv) They are non lustrous. 
(v) They are poor conductors of heat and electricity. 
(vi) They show a variety of colors. 
(vii) They exist in all the three states i.e., solids, liquids and 
gas. 
(viii) They are generally soft. 
 
Metalloids 
Metalloids have intermediate properties between those of 
metals and non metals. Examples are boron, silicon, 
germanium, arsenic etc.. 
 
Compounds 
A compound is a substance, which consists of two or more 
elements chemically combined with one another in a fixed 
proportion by mass. For example water. It is a compound 
made up of two elements hydrogen and oxygen, which are 
chemically combined in a fixed proportion of 1 : 8 by mass. 
 
Atomic weight hydrogen = 1 
Atomic weight oxygen = 16 
Their ratio in H
2
O = 2 : 16  =>  1 : 8 
 
Properties Of Compound 
 
CO  Molecules Co  Molecules
2 
 
(i) Compound cannot be separated into its components by 
physical methods. 
(ii) The properties of compound are entirely different from 
those of its constituent elements. 
(iii) Energy in the form of heat and light is usually given out or 
absorbed during the preparation of compounds. 
(iv) The composition of compound is fixed. That means the 
constituents of compound are present in fixed proportion 
by weight. 
(v) A compound is homogeneous substance. 
(vi) A compound has a fixed melting and boiling point. 
 
Mixtures 
A mixture consists of more than one substance (elements or 
compounds) in any proportion by mass. A mixture can be 
separated into two or more simpler substances by physical 
means, e.g. air is a mixture of gases like oxygen, nitrogen, 
 
 
carbon dioxide and water vapours etc. These gases are not 
chemically combined with one another. 
 
Types Of Mixture 
 
Types Of Mixture
Homogeneous Heterogenouse
Mixtures Mixtures
 
(Solutions, Colloids)        (Suspensions) 
 
Homogeneous Mixture 
It has a uniform composition throughout its mass. It has no 
visible boundaries of separation between its various 
constituents. A homogeneous mixture is also called solution. 
e.g. a mixture of sugar in water. All parts of sugar solution 
have same sugar water composition. There is no visible 
boundary of separation between sugar and water. 
 
Heterogeneous Mixture 
It does not have uniform composition throughout its mass. It 
has visible boundaries of separation between the various 
constituents, e.g. a mixture of sugar and sand. Different parts 
of this mixture will have different sugar-sand composition. 
Sugar and sand can be visibly separated from each other or 
from the mixture. 
 
Properties Of Mixture 
(i) A mixture can be separated into its constituents by simple 
physical methods. 
(ii) A mixture shows the properties of all constituents present 
in it. 
(iii) The constituents of a mixture are not in a fixed proportion 
by weight. 
(iv) Energy is usually neither given out not absorbed in the 
preparation of mixture. 
(v) A mixture does not have a definite melting and boiling 
point due to the presence of unequal amount of 
constituents. 
(vi) A mixture is usually heterogeneous. 
 
A mixture consists of two things: - 
 
Solute 
The substance present in smaller amount or the substance 
which is dissolved in a liquid to make solution is called solute. 
 
Solvent 
The substance present in larger amount or the substance in 
which solute is dissolved is called solvent, e.g. sugar solution 
is made by dissolving sugar in water. So, in sugar solution, 
sugar is solute and water is solvent. 
 
Solution 
A homogeneous mixture of two or more substance is called 
solution. Substance could be solids, liquids or gases. We 
cannot distinguish the solute particles from the solvent 
molecule even by using a microscope. Usually we think of a 
solution as a liquid that contains either a solid liquid or a gas 
dissolved in it. But we can also have solid solutions (alloys), 
gaseous solutions (air). 
 
Properties Of Solution 
(i) A solution is a homogeneous mixture. 
(ii) The size of solute particles in solution is extremely small 
(diameter=10
-6
cm).  
(iii) A solution is very stable i.e., the solute particles do not 
settle down on keeping.   
(iv) A true solution does not scatter light. 
(v) A solution cannot be filtered with a filter paper. 
 
Concentration Of Solution 
Depending upon the amount of solute present in a solution, it 
can be called dilute, concentrated or a saturated solution. 
 
Concentration of solution is either the amount of solute 
present in given mass or volume of solution or the amount of 
solute dissolved in a given mass of or volume of the solvent. 
Or 
Concentration of solution is the amount of solute present in a 
given quantity of solution. The Percentage Method is the most 
common way of expressing the concentration of solution. 
Concentration of solution is equal to mass of solute in grams 
present in 100 grams of solution. 
 
For example, 10 percent solution of common salt means, 10 
grams of common salt present in 100 grams of water. 
 
100 gram salt solution = 10 grams of salt + 90 grams of water 
 
Concentration Of Solution = 100
Solution Of Mass
Solute Of Mass
× 
Where 
Mass of solution = Mass Of Solute  +  Mass Of Solvent 
 
Example 
For a 10 % salt solution we will say  
Mass of solute (salt) = 10 grams 
Mass of solvent (water) = 90 grams 
Concentration Of Solution = 100
90 10
10
×
+
 = 100
100
10
× =10% 
 
Saturated Solution 
When at a particular temperature as maximum possible solute 
is dissolved in a solution as it is capable of, then it is called 
saturated solution. 
 
Unsaturated Solution 
When the amount of solute in a solution is less than its 
saturation level. Or at any given temperature if the amount of 
solute can be increased again and again the solution is called 
unsaturated solution.  
 
Solubility 
Solubility is defined as the maximum amount of solute, which 
is required to dissolve in the solvent at a given temperature to 
make a saturated solution. For example if at 40
0 
c, 36.5 gm of 
sodium chloride is required to dissolve in water to make a 
saturated solution then it will be said that, the solubility of 
sodium chloride at 40
0
 c is 36.5 gm. 
 
Aqueous Solutions 
The solutions made by dissolving various solutes in water are 
called aqueous solutions. Water is a universal solvent. 
 
Non-Aqueous Solutions 
The solutions made by dissolving solutes in organic liquids or 
solvents other than water are called non-aqueous solutions. 
 
Suspension 
A suspension is a heterogeneous mixture in which the small 
particles of solids are spread throughout in a liquid without 
dissolving in it. 
 
 
Properties Of Suspension 
(i) A suspension is a heterogeneous mixture. 
(ii) Size of solute particles in suspension is quite large. The 
size is larger than 10
-5
cm in diameters. 
(iii) The particles of a suspension can be seen easily. 
(iv) The particles of a suspension do not pass through a filter 
paper. So, a suspension can be separated by filtration. 
(v) Suspension particles are unstable. They settle down after 
some time. 
(vi) A suspension scatters beam of light passing through it, 
e.g. chalk-water mixture, paint, sand, water mixture, 
flour-water mixture, muddy water. Muddy water is a 
suspension of soil particles in water; paint is a suspension 
of colored substance in various liquids. 
 
Colloids 
Colloids are a kind of solution in which the size of the solute 
particles is bigger than that of a true solution, but smaller than 
that of a suspension. 
 
Properties Of Colloids 
(i) A colloid appears to be homogeneous, but actually it is 
heterogeneous. 
(ii) The size of the particles in a colloid is bigger than those in 
a true solution, but smaller than those of suspension. It is 
between 10
-7
 and 10
-5 
in diameter.      
(iii) Particles of colloid can pass through a filter paper. 
(iv) Colloids are quite stable. 
(v) A colloid scatters a beam of light, e.g. starch solution, 
milk, ink, blood, soap solution, toothpaste, and mist. Mist 
is a solution of water vapors suspended in air. 
 
Tyndall Effect 
The scattering of light by colloidal particles is called Tyndall 
Effect. The path of light inside a colloidal becomes visible 
because the solute particles in a colloidal solution are big 
enough to scatter or disperse the light rays falling on them in 
all directions. 
 
Separating Components Of A Mixture 
Different methods of separation are used to get individual 
components from a mixture. Separation makes it possible to 
study and use the individual components of a mixture. 
 
Obtaining Coloured Component From A Blue Black Ink 
It is done by Evaporation. 
By this process a volatile component can be separated from its 
non volatile solute. 
 
Separating Cream From Milk 
It is done by Centrifugation. 
The principle of this process is that the denser particles are 
forced to the bottom and the lighter particles stay at the top 
when spun rapidly. 
 
 
Separating A Mixture Of Two Immiscible Liquids 
It is done by Separating Funnel. 
The principle of this process is that immiscible liquids separate 
out in layers depending upon their densities. 
                  
Separating A Mixture Of Salt And Ammonium Chloride 
It is done by Sublimation. 
This process is done to separate a sublimable volatile 
component from a non sublimable impurity. 
       
Separating A Mixture Of Colors Of A Dye 
It is done by Chromatogarphy. 
It is a technique used to separate those solutes that dissolve 
in the same solvent. 
 
 
 
                 
 
Separating A Mixture Of Two Miscible Liquids 
It is done by Distillation. 
In this process the two miscible liquids boil without 
decomposition and have sufficient difference in their boiling 
points. 
 
Separating A Mixture Of Gases From Air  
It is done by Fractional Distillation. 
A simple fractionating coloumn is tube packed with glass 
beads. These beads provide surface for the vapours to cool 
and condense repeatedly. 
 
 
Separating Pure Copper Sulphate From An Impur 
Sample 
It is done by Crystallization. 
It separates a pure solid in the form of its crystals from its 
solution. 
 
Physical And Chemical Changes 
 
Physical Properties 
Those properties which can be observed and specified like 
colour, hardness, rigidity, fluidity, density, melting point, 
boiling point etc.. 
 
Physical Change 
The interconversion of states is a physical change because 
these changes take place without changing composition and  
no change in the chemical nature of substance. 
 
Examples 
(i) Boiling of water to form steam. 
(ii) Melting of butter in a pan. 
(iii) Dissolving common salt in water. 
(iv) Making a fruit salad with raw fruits. 
(v) Freezing of a substance. 
 
Chemical Properties 
Those properties which cannot be observed or specified 
directly are called chemical properties. 
 
Chemical Change 
A chemical change brings change in the chemical properties of 
a substance and we get new substances. 
 
Examples 
(i) Cooking of food. 
(ii) Burning of a substance. 
(iii) Rusting of almirah. 
(iv) Growth of a plant. 
(v) Digestion of food. 
 
Purification Of Water At Waterworks