CBSE Class-12 Chemistry Quick Revision Notes
Chapter-02: Solutions
• Solutions:
Solutions are the homogeneous mixtures of two or more than two components.
• Binary solution:
A solution having two components is called a binary solution.
• Components of a binary solution
It includes solute and solvent.
a) When the solvent is in solid state, solution is called solid solution.
b) When the solvent is in liquid state, solution is called liquid solution.
c) When the solvent is in gaseous state, solution is called gaseous solution.
• Concentration:
It is the amount of solute in given amount of solution.
• Mass by volume percentage (w/v):
Mass of the solute dissolved in 100 mL of solution.
• Molality (m) is the number of moles of solute present in 1kg of solvent.
Number of moles of solute
Molality =
Mass of solvent in kilograms
• Molarity (M) is the number of moles of solute present in 1L of solution.
Number of moles of solute
Molality =
Volume of solution in litres
• Normality is the number of gram equivalent of solute dissolved per litre of solution.
Number of gram equivalent of solute
Molality =
Volume of solution in litres
• Solubility:
It is the maximum amount that can be dissolved in a specified amount of solvent at a
specified temperature.
• Saturated solution:
It is a solution in which no more solute can be dissolved at the same temperature and
pressure.
• In a nearly saturated solution if dissolution process is an endothermic process, solubility
increases with increase in temperature.
• In a nearly saturated solution if dissolution process is an exothermic process, solubility
decreases with increase in temperature.
• Henry’s Law:
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, It states “at a constant temperature the solubility of gas in a liquid is directly
proportional to the pressure of gas”. In other words, “the partial pressure of gas in
vapour phase is proportional to the mole fraction of the gas in the solution”.
P = KH x
• When a non-volatile solute is dissolved in a volatile solvent, the vapour pressure of
solution is less than that of pure solvent.
• Raoult’s law:
It states that “for a solution of volatile liquids the partial vapour pressure of each
component in the solution is directly proportional to its mole fraction”.
p1 = p 01 X 1 ; p2 = p 0 2 X 2
• Using Dalton’s law of partial pressure the total pressure of solution is calculated.
ptotal = p 01 + ( p2 − p 01 ) X 2
• Comparison of Raoult’ law and Henry’s law:
It is observed that the partial pressure of volatile component or gas is directly
proportional to its mole fraction in solution. In case of Henry’s Law the proportionality
constant is KH and it is different from p10 which is partial pressure of pure component.
Raoult’s Law becomes a special case of Henry’s Law when KH becomes equal to p10 in
Henry’s law.
• Classification of liquid –liquid solutions:
It can be classified into ideal and non-ideal solutions on basis of Raoult’s Law.
• Ideal solutions:
a) The solutions that obey Raoult’s Law over the entire range of concentrations are
known as ideal solutions.
b) ∆ mix H = 0 and ∆ mixV = 0
c) The intermolecular attractive forces between solute molecules and solvent molecules
are nearly equal to those present between solute and solvent molecules i.e. A-A and
B-B interactions are nearly equal to those between A-B.
• Non-ideal solutions:
a) When a solution does not obey Raoult’s Law over the entire range of concentration,
then it is called non-ideal solution.
b) ∆ mix H ≠ 0 and ∆ mixV ≠ 0
c) The intermolecular attractive forces between solute molecules and solvent molecules
are not equal to those present between solute and solvent molecules i.e. A-A and B-B
interactions are not equal to those between A-B
• Types of non- ideal solutions:
There are two types of non-ideal solutions namely,
a) Non ideal solution showing positive deviation
b) Non ideal solution showing negative deviation
• Non ideal solution showing positive deviation
a) The vapour pressure of a solution is higher than that predicted by Raoult’s Law.
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Chapter-02: Solutions
• Solutions:
Solutions are the homogeneous mixtures of two or more than two components.
• Binary solution:
A solution having two components is called a binary solution.
• Components of a binary solution
It includes solute and solvent.
a) When the solvent is in solid state, solution is called solid solution.
b) When the solvent is in liquid state, solution is called liquid solution.
c) When the solvent is in gaseous state, solution is called gaseous solution.
• Concentration:
It is the amount of solute in given amount of solution.
• Mass by volume percentage (w/v):
Mass of the solute dissolved in 100 mL of solution.
• Molality (m) is the number of moles of solute present in 1kg of solvent.
Number of moles of solute
Molality =
Mass of solvent in kilograms
• Molarity (M) is the number of moles of solute present in 1L of solution.
Number of moles of solute
Molality =
Volume of solution in litres
• Normality is the number of gram equivalent of solute dissolved per litre of solution.
Number of gram equivalent of solute
Molality =
Volume of solution in litres
• Solubility:
It is the maximum amount that can be dissolved in a specified amount of solvent at a
specified temperature.
• Saturated solution:
It is a solution in which no more solute can be dissolved at the same temperature and
pressure.
• In a nearly saturated solution if dissolution process is an endothermic process, solubility
increases with increase in temperature.
• In a nearly saturated solution if dissolution process is an exothermic process, solubility
decreases with increase in temperature.
• Henry’s Law:
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, It states “at a constant temperature the solubility of gas in a liquid is directly
proportional to the pressure of gas”. In other words, “the partial pressure of gas in
vapour phase is proportional to the mole fraction of the gas in the solution”.
P = KH x
• When a non-volatile solute is dissolved in a volatile solvent, the vapour pressure of
solution is less than that of pure solvent.
• Raoult’s law:
It states that “for a solution of volatile liquids the partial vapour pressure of each
component in the solution is directly proportional to its mole fraction”.
p1 = p 01 X 1 ; p2 = p 0 2 X 2
• Using Dalton’s law of partial pressure the total pressure of solution is calculated.
ptotal = p 01 + ( p2 − p 01 ) X 2
• Comparison of Raoult’ law and Henry’s law:
It is observed that the partial pressure of volatile component or gas is directly
proportional to its mole fraction in solution. In case of Henry’s Law the proportionality
constant is KH and it is different from p10 which is partial pressure of pure component.
Raoult’s Law becomes a special case of Henry’s Law when KH becomes equal to p10 in
Henry’s law.
• Classification of liquid –liquid solutions:
It can be classified into ideal and non-ideal solutions on basis of Raoult’s Law.
• Ideal solutions:
a) The solutions that obey Raoult’s Law over the entire range of concentrations are
known as ideal solutions.
b) ∆ mix H = 0 and ∆ mixV = 0
c) The intermolecular attractive forces between solute molecules and solvent molecules
are nearly equal to those present between solute and solvent molecules i.e. A-A and
B-B interactions are nearly equal to those between A-B.
• Non-ideal solutions:
a) When a solution does not obey Raoult’s Law over the entire range of concentration,
then it is called non-ideal solution.
b) ∆ mix H ≠ 0 and ∆ mixV ≠ 0
c) The intermolecular attractive forces between solute molecules and solvent molecules
are not equal to those present between solute and solvent molecules i.e. A-A and B-B
interactions are not equal to those between A-B
• Types of non- ideal solutions:
There are two types of non-ideal solutions namely,
a) Non ideal solution showing positive deviation
b) Non ideal solution showing negative deviation
• Non ideal solution showing positive deviation
a) The vapour pressure of a solution is higher than that predicted by Raoult’s Law.
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