Class 9
Chapter 2
Is Matter Around Us Pure?
Introduction to Matter
The substance which has mass and occupies a certain space is called matter. The matter
can be divided into two types:
2.1 What is a mixture?
The mixture is formed by combining two or more substances in which each substance retains its
characteristics. In general we can say that a mixture contains more than one pure substance.
2.1.1 Types Of Mixtures
There are two types of mixture, homogeneous and heterogeneous.
[A] Homogeneous Mixture:
The mixture which has the same proportion of its component throughout the mixture is called a
homogeneous mixture.
For example, Salt dissolved in water; Sugar dissolved in water.
[B] Heterogeneous mixture:
The mixture which has the varied proportion of its component throughout the mixture is called a
heterogeneous mixture.
For example, Mixtures of sodium chloride and iron filings ; oil and water.
2.2 What is a solution?
The solution is defined as a substance in which two or more substances are completely
dissolved into each other and cannot be filtered out.
•The solution is a special type of homogeneous mixture in which only one type of phase is
present. For example, lemonade, Soda Water.
, •A solution has a solvent and a solute as its components. The component of the solution that
dissolves the other component or the component present in large quantity is called solvent. The
component of the solution that is dissolved in the solvent or present in lesser quantity is called
the solute.
For example, a solution of sugar in water is a solid in liquid solution.
In this solution, sugar is the solute and water is the solvent.
Properties of a solution:
•A solution is a homogeneous mixture.
•The particles of a solution are smaller than 1 nm in diameter. So they cannot be seen by naked
eyes.
•It does not show the Tyndall Effect.
•The solute particles cannot be separated from the mixture by the process of filtration. The
solute particles do not settle down when left undisturbed, that is, a solution is stable.
2.2.1 Concentration of a solution
The concentration of a solution is the amount of solute present in a given amount of the solution
or the amount of solute dissolved in a given mass or volume of solvent.
Concentration = Amount of Solute
Amount of Solution
There are various ways of expressing the concentration of a solution. Such as
(i) Mass by mass percentage of a solution =
= Mass of solute × 100
Mass of solution
(ii) Mass of volume percentage of a solution
= Mass of Solute ×100
Volume of Solution
(iii) Volume by volume percentage of a solution
= Volume of solute ×100
Volume of Solution
Example 2.1
Chapter 2
Is Matter Around Us Pure?
Introduction to Matter
The substance which has mass and occupies a certain space is called matter. The matter
can be divided into two types:
2.1 What is a mixture?
The mixture is formed by combining two or more substances in which each substance retains its
characteristics. In general we can say that a mixture contains more than one pure substance.
2.1.1 Types Of Mixtures
There are two types of mixture, homogeneous and heterogeneous.
[A] Homogeneous Mixture:
The mixture which has the same proportion of its component throughout the mixture is called a
homogeneous mixture.
For example, Salt dissolved in water; Sugar dissolved in water.
[B] Heterogeneous mixture:
The mixture which has the varied proportion of its component throughout the mixture is called a
heterogeneous mixture.
For example, Mixtures of sodium chloride and iron filings ; oil and water.
2.2 What is a solution?
The solution is defined as a substance in which two or more substances are completely
dissolved into each other and cannot be filtered out.
•The solution is a special type of homogeneous mixture in which only one type of phase is
present. For example, lemonade, Soda Water.
, •A solution has a solvent and a solute as its components. The component of the solution that
dissolves the other component or the component present in large quantity is called solvent. The
component of the solution that is dissolved in the solvent or present in lesser quantity is called
the solute.
For example, a solution of sugar in water is a solid in liquid solution.
In this solution, sugar is the solute and water is the solvent.
Properties of a solution:
•A solution is a homogeneous mixture.
•The particles of a solution are smaller than 1 nm in diameter. So they cannot be seen by naked
eyes.
•It does not show the Tyndall Effect.
•The solute particles cannot be separated from the mixture by the process of filtration. The
solute particles do not settle down when left undisturbed, that is, a solution is stable.
2.2.1 Concentration of a solution
The concentration of a solution is the amount of solute present in a given amount of the solution
or the amount of solute dissolved in a given mass or volume of solvent.
Concentration = Amount of Solute
Amount of Solution
There are various ways of expressing the concentration of a solution. Such as
(i) Mass by mass percentage of a solution =
= Mass of solute × 100
Mass of solution
(ii) Mass of volume percentage of a solution
= Mass of Solute ×100
Volume of Solution
(iii) Volume by volume percentage of a solution
= Volume of solute ×100
Volume of Solution
Example 2.1
