CHAPTER-2
Is Matter Around Us Pure?
A pure substance consists of a single type of particle.
Most of the matter around us exists as mixtures, which is constituted by 2 or more
pure components for eg: sea water, minerals, soil etc.
Solution is a homogeneous mixture of two or more substances. Eg: Lemonade, soda
water etc. In solution there is homogeneity at the particle level. eg: Lemonade tastes
the same throughout.
Solid solutions— Alloys —- Mixture of 2 or more metals or a metal and a non-metal
and cannot be separated by physical methods. Eg: Brass is a mixture of 30% zinc and
70% copper.
Gaseous solutions— air
Solution has 2 components — Solvent (Component that dissolves another
component or present in larger amount). Solute (Component that is dissolved in the
solvent or present in lesser amount).
Properties of a solution:
1. Homogeneous Mixture
2. Particles are < 1nm in diameter
3. Cannot be seen by naked eyes
4. Small particle size, so do not scatter a beam of light passing through the solution
5. Path of light is not visible
6. Solute particles cannot be separated through filtration.
7. Solution is stable as solute particles do not settle down when left undisturbed.
, Saturated solution: At any particular temperature, a solution that has dissolved as
much solute as it is capable of dissolving.
Solubility: The amount of solute present in the saturated solution at that particular
temperature.
Unsaturated solution: If the amount of solute contained in a solution is less than the
saturation level, it is called an unsaturated solution.
Concentration of a solution: Amount (mass or volume) of solute present in a given
amount of solution.
Ways of expressing the concentration:
1. Mass by mass percentage of a solution = (Mass of solute/Mass of solution) *100
2. Mass by volume percentage of a solution = (Mass of solute/Volume of solution) *100
3. Volume by volume percentage of a solution = (Volume of solute/Volume of solution)
*100
A suspension is a heterogeneous mixture in which the solute particles do not dissolve
but remain suspended throughout the bulk of the medium.
Properties of suspension:
1. Heterogeneous mixture
2. Particles can be seen by naked eye.
3. Particles scatter a beam of light passing through it and make its path visible.
4. Suspension is unstable as solute particles settle down when left undisturbed.
5. Solute particles can be separated through filtration.
Colloidal solution is a heterogeneous mixture and the particles of a colloid (cannot be
seen through naked eye but can easily scatter a beam of visible light) are uniformly
spread throughout the solution. Eg: Milk
Is Matter Around Us Pure?
A pure substance consists of a single type of particle.
Most of the matter around us exists as mixtures, which is constituted by 2 or more
pure components for eg: sea water, minerals, soil etc.
Solution is a homogeneous mixture of two or more substances. Eg: Lemonade, soda
water etc. In solution there is homogeneity at the particle level. eg: Lemonade tastes
the same throughout.
Solid solutions— Alloys —- Mixture of 2 or more metals or a metal and a non-metal
and cannot be separated by physical methods. Eg: Brass is a mixture of 30% zinc and
70% copper.
Gaseous solutions— air
Solution has 2 components — Solvent (Component that dissolves another
component or present in larger amount). Solute (Component that is dissolved in the
solvent or present in lesser amount).
Properties of a solution:
1. Homogeneous Mixture
2. Particles are < 1nm in diameter
3. Cannot be seen by naked eyes
4. Small particle size, so do not scatter a beam of light passing through the solution
5. Path of light is not visible
6. Solute particles cannot be separated through filtration.
7. Solution is stable as solute particles do not settle down when left undisturbed.
, Saturated solution: At any particular temperature, a solution that has dissolved as
much solute as it is capable of dissolving.
Solubility: The amount of solute present in the saturated solution at that particular
temperature.
Unsaturated solution: If the amount of solute contained in a solution is less than the
saturation level, it is called an unsaturated solution.
Concentration of a solution: Amount (mass or volume) of solute present in a given
amount of solution.
Ways of expressing the concentration:
1. Mass by mass percentage of a solution = (Mass of solute/Mass of solution) *100
2. Mass by volume percentage of a solution = (Mass of solute/Volume of solution) *100
3. Volume by volume percentage of a solution = (Volume of solute/Volume of solution)
*100
A suspension is a heterogeneous mixture in which the solute particles do not dissolve
but remain suspended throughout the bulk of the medium.
Properties of suspension:
1. Heterogeneous mixture
2. Particles can be seen by naked eye.
3. Particles scatter a beam of light passing through it and make its path visible.
4. Suspension is unstable as solute particles settle down when left undisturbed.
5. Solute particles can be separated through filtration.
Colloidal solution is a heterogeneous mixture and the particles of a colloid (cannot be
seen through naked eye but can easily scatter a beam of visible light) are uniformly
spread throughout the solution. Eg: Milk
