XII Chemistry Chapter 2
Solutions
Solubility
Topics covered
Solubility
Solubility of solid in liquid
Solubility of gas in liquid
Henry’s law & its applications
Raoults law
&
Solubility :
It is the maximum amount of solute particle dissolved in a specified
amount of solvent at a given temperature.
The concentration of saturated solution at a given temperature.
Saturated & Unsaturated solutions
A solution in which no more solute can be dissolved at the same
temperature and pressure is called a saturated solution.
A solution in which more solute can be dissolved at the same
temperature is called an unsaturated solution.
Solubility of solid in liquid depends on ;
1) Nature of solute / solvent ⑫
2) Temperature
⑳
3) Pressure
#I ⑳ OL
1) Nature of solute / solvent
It is observed that polar solutes dissolve in polar solvents and
non polar solutes in non polar solvents - “like dissolves like”.
2) Effect of temperature
If the dissolution process is endothermic (∆H > 0),
The solubility should increase with rise in temperature.
If it is exothermic (∆H < 0) the solubility should increase with
decrease in temperature.
3) Effect of Pressure
Since solids and liquids are highly incompressible, pressure does
not have any significant effect on solubility of solids in liquids.
Solubility of gas in liquid depends on ;
1) Nature of solute / solvent - “like dissolves like”.
2) Temperature : Solubility of gases in liquids decreases with
rise in temperature.
3) Pressure
Solubility of gas in liquid
Effect of Pressure
Henry’s Law
It states that the solubility of gas in liquid at a particular temperature
is directly proportional to the pressure of the gas in equilibrium with
the liquid at that temperature.
PXX KH =
Henry's
cont
-
-
P
solabilit
Henry’s Law OK
C
B
schalt
↓ solubility T
P O
A
Temp solubility ↑ .
· i
L
.
✗→
↓ Kat
P = k+X +0
mx + C
Y =
-
-
The value of KH depends on the nature of the gas and temperature.
:
As the value of KH increases,the solubility of the gas in the liquid
decreases.
✓ As the temperature increases solubility of a gas in a liquid decreases.
It is due to this reason that aquatic species are more comfortable in
cold waters rather than in warm waters.
Applications of Henry’s Law
1) In the production of carbonated drinks
2) In the deep sea diving (bends / compressed sickness)
3) For climbers or people living in high altitude (Anoxia)
1. To increase the solubility of CO₂ in soft drinks and soda water,
the bottle is sealed under high pressure.
2. Scuba divers carry oxygen cylinders to breath under deep sea.
At high pressure under water, the solubility of gases in blood increases.
When the divers come towards surface, the pressure gradually
decreases. This releases the dissolved gases and leads to the formation of
bubbles of nitrogen in the blood.This blocks capillaries & creates a medical
condition known as bends. To avoid bends the cylinders used by scuba
divers are filled with air diluted with helium(11.7% He, 56.2% N & 32.1% O).
3. At high altitudes the partial pressure of oxygen is less than that at the
ground level. This leads to low concentrations of oxygen in the blood and
tissues of people living at high altitudes or climbers. Low blood oxygen
causes climbers to become weak and unable to think clearly.
This condition is known as anoxia.
XII Chemistry Chapter 2
Solutions
Raoult’s Law
Vapour pressure Pni PB°
It is the pressure exerted by the
vapours of the liquid in equilibrium
A B
with the liquid at that temperature. =
=
P Xa X B
E- P Pa
= P = PYB
① ⑬ --
-
Vapour Pressure of Liquid-Liquid Solutions
Raoult’s Law
For a solution of volatile liquids, the partial vapour pressure
of each liquids is directly proportional to its mole fraction.
Pa
= Pa
Raoult’s Law (Liquid in liquid)
-Pr
dP
=
O
PA
-
r PB
XA = 1
XA = 0
mule Fraction
= X = 0
X
st
you -- machi n
Thank
