Knowledge Points
1.
Solutions are the
homogeneous mixtures of two or more than two
components.
2. Binary solution: A
solution having two components is called a binary solution. Components of a binary solution are 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.
3.
Concentration is the
amount of solute in given amount of solution.
4.
Mass by volume percentage
(w/v): Mass of the solute dissolved in 100
mL of solution.
5.
Molality (m) is the
number of moles of solute present in 1kg of
solvent.
6. Molarity (M) is the
number of moles of solute present in 1L of
solution.
7. Normality is the number
of gram equivalent of solute dissolved per litre
of solution.
8. Solubility is its maximum
amount that can be dissolved in a specified
amount of solvent at a
specified temperature.
9. A solution in which no
more solute can be dissolved at the same temperature and pressure is
called a
saturated solution.
10. In a nearly saturated solution if dissolution process is an endothermic process, solubility increases with increase in temperature.
10. In a nearly saturated solution if dissolution process is an endothermic process, solubility increases with increase in temperature.
11. In a
nearly saturated solution if dissolution process is an exothermic process,
solubility decreases with increase in temperature.
12. Henry’s Law: The law
states at a constant temperature the solubility of gas in a liquid is directly proportional to the pressure of
gas. Henry’s law can also be stated as the partial pressure of gas in vapour
phase is proportional to the mole fraction of the gas in the solution.
P = KH
x
13. When a non-volatile
solute is dissolved in a volatile solvent, the vapour pressure of solution is less than that of pure solvent.
14. According to Raoult’s law
for a solution of volatile liquids the partial
vapour pressure of each component in the solution is directly proportional to
its mole fraction.
p1 = po1 x1
; p2 = po2
x2
Using Dalton’s law of partial pressure the total
pressure of solution is calculated.
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15.
On comparison of Raoult’s 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 p 0 which is
partial pressure of pure component. Raoult’s Law becomes a special case of
Henry’s Law when KH becomes equal to p01
in Henry’s law.
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16. Liquid –liquid solutions
can be classified into ideal and non-ideal solutions on basis of Raoult’s Law.
Ideal
solutions
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Non-
ideal solutions
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The
solutions that obey Raoult’s Law over the entire range of concentrations are
known as ideal solutions.
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When
a solution does not obey Raoult’s Law over the entire range of concentration,
then it is called non-ideal solution.
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△mix
H = 0 and △mixV = 0
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△mix
H = 0 and △mixV = 0
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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
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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
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Non
ideal solution showing positive deviation
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Non
ideal solution showing negative deviation
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The
vapour pressure of a solution
is
higher than that predicted by Raoult’s Law
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The
vapour pressure of a solution
is
lower than that predicted by Raoult’s Law
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The
intermolecular attractive forces between solute-solvent molecules are weaker
than those between solute-solute and solvent-solvent molecules i.e.
A-B
< A-A and B-B interactions
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The
intermolecular attractive forces between solute-solvent molecules are stronger
than those between solute-solute and solvent-solvent
molecules i.e. A-B > A-A and B-B interactions
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19. There are two types of
azeotropes called minimum boiling azeotrope and maximum boiling azeotrope.
20. The solutions which show
a large positive deviation from Raoult’s
law form minimum boiling azeotrope at a specific composition.
21. The solutions that show
large negative deviation from Raoult’s law
form maximum boiling azeotrope at a specific
composition.
22. Properties of solution
which depends on only the number of solute
particles but not on the nature of solute are called colligative properties.
23.
There are four
colligative properties:
a.
Relative lowering of
vapour pressure
b.
Elevation of boiling point
c.
Depression of freezing point
d.
Osmotic pressure
25. Elevation of boiling
point: The difference in boiling points of solution ( Tb ) and pure solvent ( T 0 )
is called elevation in boiling point
26. Depression of freezing
point: The lowering of vapour pressure of solution causes a lowering of freezing point compared to that of pure solvent. The difference in freezing
point of the pure solvent ( Tf0 ) and solution ( Tf )
is called the depression in freezing point.
27. For a dilute solution
depression in freezing point is a colligative property because it is directly proportional to molal concentration of solute.
28. Osmosis:
The phenomenon of flow of solvent molecules through a semi permeable membrane from pure solvent to solution is
called osmosis.
29. Osmotic
pressure: The excess pressure that must be applied to solution to prevent the
passage of solvent into solution through a semi permeable membrane is called
osmotic pressure.
Osmotic pressure is a
colligative property as it depends on the number of solute particles and not on
their identity.
For a dilute solution, osmotic pressure ( 𝜋 ) is directly proportional to the concentration (C) of the solution i.e. 𝜋 ＝ CRT
30. Osmotic
pressure can also be used to determine the molar mass of solute using
the equation
M2 = w2RT
Pi V
31. Two
solutions having same osmotic pressure at a given temperature are called isotonic solution.
32. If a solution has more
osmotic pressure than other solution it is called hypertonic solution.
33. If a solution has less
osmotic pressure than other solution it is called hypotonic solution.
34. Reverse
osmosis: The process of movement of solvent through a semi permeable membrane from the solution to the pure solvent by applying
excess pressure on the solution side is called reverse osmosis.
35. Colligative
properties help in calculation of molar mass of solutes.
36. Molar
mass that is either lower or higher than expected or normal molar mass is
called as abnormal molar mass.
37. van’t
Hoff factor (i)accounts for the extent of dissociation or association
Value
of i is less than unity in case solute undergo association Value of i is
greater than unity in case solute undergo dissociation
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