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Chemistry Notes for class 12 Chapter 2
Solutions
Solution is a homogeneous mixture of two or more substances in same or different physical
phases. The substances forming the solution are called components of the solution. On the basis
of number of components a solution of two components is called binary solution.
Solute and Solvent
In a binary solution, solvent is the component which is present in large quantity while the other
component is known as solute.
Classification of Solutions
(A) Following types of solutions are seen on the basis of physical state of solute and solvent.
[if water is used as a solvent, the solution is called aqueous solution and if not, the solution is
called non-aqueous solution.]
(B) Depending upon the amount of solute dissolved in a solvent we have the following types of
solutions:
(i) Unsaturated solution A solution in which more solute can be dissolved without raising
temperature is called an unsaturated solution.
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(ii) Saturated solution A solution in which no solute can be dissolved further at a given
temperature is called a saturated solution.
(iii) Supersaturated solution A solution which contains more solute than that would be
necessary to saturate it at a given temperature is called a supersaturated solution.
Solubility
The maximum amount of a solute that can be dissolved in a given amount of solvent (generally
100 g) at a given temperature is termed as its solubility at that temperature.
The solubility of a solute in a liquid depends upon the following factors:
(i) Nature of the solute
(ii) Nature of the solvent
(iii) Temperature of the solution
(iv) Pressure (in case of gases)
Henry’s Law
The most commonly used form of Henry‟s law states “the partial pressure (P) of the gas in
vapour phase is proportional to the mole fraction (x) of the gas in the solution” and is expressed
as
p = KH . x
Greater the value of KH, higher the solubility of the gas. The value of KH decreases with
increase in the temperature. Thus, aquatic species are more comfortable in cold water [more
dissolved O2] rather than Warm water.
Applications
1. In manufacture of soft drinks and soda water, CO2 is passed at high pressure to increase its
solubility.
2. To minimise the painful effects (bends) accompanying the decompression of deep sea divers.
O2diluted with less soluble. He gas is used as breathing gas.
3. At high altitudes, the partial pressure of O2 is less then that at the ground level. This leads to
low concentrations of O2 in the blood of climbers which causes „anoxia‟.
Concentration of Solutions
The concentration of a solution is defined as the relative amount of solute present in a solution.
On the basis of concentration of solution there are two types of solutions.
(i) Dilute solution
(ii) Concentrated solution
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Chemistry Notes for class 12 Chapter 2
Solutions
Solution is a homogeneous mixture of two or more substances in same or different physical
phases. The substances forming the solution are called components of the solution. On the basis
of number of components a solution of two components is called binary solution.
Solute and Solvent
In a binary solution, solvent is the component which is present in large quantity while the other
component is known as solute.
Classification of Solutions
(A) Following types of solutions are seen on the basis of physical state of solute and solvent.
[if water is used as a solvent, the solution is called aqueous solution and if not, the solution is
called non-aqueous solution.]
(B) Depending upon the amount of solute dissolved in a solvent we have the following types of
solutions:
(i) Unsaturated solution A solution in which more solute can be dissolved without raising
temperature is called an unsaturated solution.
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(ii) Saturated solution A solution in which no solute can be dissolved further at a given
temperature is called a saturated solution.
(iii) Supersaturated solution A solution which contains more solute than that would be
necessary to saturate it at a given temperature is called a supersaturated solution.
Solubility
The maximum amount of a solute that can be dissolved in a given amount of solvent (generally
100 g) at a given temperature is termed as its solubility at that temperature.
The solubility of a solute in a liquid depends upon the following factors:
(i) Nature of the solute
(ii) Nature of the solvent
(iii) Temperature of the solution
(iv) Pressure (in case of gases)
Henry’s Law
The most commonly used form of Henry‟s law states “the partial pressure (P) of the gas in
vapour phase is proportional to the mole fraction (x) of the gas in the solution” and is expressed
as
p = KH . x
Greater the value of KH, higher the solubility of the gas. The value of KH decreases with
increase in the temperature. Thus, aquatic species are more comfortable in cold water [more
dissolved O2] rather than Warm water.
Applications
1. In manufacture of soft drinks and soda water, CO2 is passed at high pressure to increase its
solubility.
2. To minimise the painful effects (bends) accompanying the decompression of deep sea divers.
O2diluted with less soluble. He gas is used as breathing gas.
3. At high altitudes, the partial pressure of O2 is less then that at the ground level. This leads to
low concentrations of O2 in the blood of climbers which causes „anoxia‟.
Concentration of Solutions
The concentration of a solution is defined as the relative amount of solute present in a solution.
On the basis of concentration of solution there are two types of solutions.
(i) Dilute solution
(ii) Concentrated solution
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