- SOLUTION: It is a homogeneous mixture of two or more non reading components.
- SOLUTE: Which is present in less amount or (which gets dissolved).
- SOLVENT: Which is present in larger amount or (which can dissolve any solute in it).
Ex; If salt(solute) is dissolved in water(solvent).
- BINARY SOLUTION: The solution which have two components (i.e., one solute and one solvent).
Types of Solution: There are nine types of solution.
(NOTE: The physical state of solution in same as physical state of solvent)
- Expressing % age (w/w):
Mass % age of component = Mass of component / total mass of solution × 100
2. Volume %age (v/v):
Volume %age any component = Volume of component / total volume of solution × 100
[used for liquid-liquid solution]
3. Mass by Volume %age (w/v):
Mass by Volume %age = Mass of solute / volume of solution/100
4. Parts per million(ppm):
Parts per million = Number of parts of the component/total number of parts of all the component × 100
5. Mole Fraction:
6. Molarity(M) =
number of moles of solute/volume of solution (in litre)
Unit – mol/litre or M
(Molarity is temp. dependent because volume change with temp)
7. Molality (molal) [m]:
number of moles of solute/ mass of solvent (in kg) Unit – mol/kg or m
• Solubility: –
Solubility of a substance is its maximum amount that can be dissolve in a specific amount of solvent at a given temperature and pressure.
• Nature of solute & solvent
Solubility of solid and liquid:
1. Like dissolve like
- Dissolution: When a solid solute is added to the solvent some solute dissolve and its concentration increases in solution is called dissolution.
- Crystallisation: Some solute particles in solution collide with the solid solute particle and get separated art of solution is called crystallization.
- Dynamic Equilibrium: A stage is reached when the two process occur at the same rate. Under such condition number of solute particles going into solution will be equal to the solute particle and state of dynamic equilibrium is reached. Solute + solvent + ⇌ solution
- Saturated Solution: A solution in which no more solute can be dissolved at the same temperature and pressure is called saturated solution.
- Unsaturated Solution: A solution in which more solute can be dissolved at the same temperature and pressure is called unsaturated solution.
Effect of temperature on solubility of solid in liquid:
Solute + Solvent ⇌ Solution
When temperature is increased then solubility is increased when the dissolution process is endothermic.
Solute + Solvent ⇌ Solution
When temperature is decreased then solubility is decreased when the dissolution process is exothermic.
- Effect of pressure: There is no effect of solubility od solid in liquid because both are highly incompressible.
Solubility of gas in liquid:
Henry law: It states that at constant temperature the solubility of gas in liquid is directly proportion to the pressure of the gas.
– Partial pressure of the gas in vapour phase is proportion to the mole fraction of the
gas in the solution.
P α X
P = K HX (Henry constant)
• Value of KH increases with increase in temperature.
T ↑ KH ↑ S↓
Ques: Why Aquatic life is more comfortable in cold weather?
Ans: When temperature is decrease value of KH is decrease, hence solubility of gas in liquid increases.
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Application of Henry’s Law:
1. To increase the solubility of CO2 in soft drink and soda water the bottle is sealed under high pressure.
2. When scuba divers dive in the ocean than due to increase pressure solubility of atmospheric gases increases in blood. When divers come towards surfaces the pressure gradually decreases the release the dissolve gases and leads to the formation of bubbles of nitrogen in the blood this blocks capillary and creates a medical condition known as bends.
To avoid bends as well as toxic effect of high concentration of N2 in the blood the tank is used by scuba divers or filled with air diluted with helium approx. [11.7% He, 56.2% N2, 32.1% O2]
3. At high altitude the partial pressure of O2 is less than at the ground level. These leads to law concentration of O2 in the blood and tissue of people living at high altitude or climbers low blood oxygen causes climber to become weak and unable to think clearly these conditions is known as anoxia.
▪ Effect of temperature on solubility of gas in liquid:
Solute(g) + Solvent(l) ⇌ Solution
According to Lech atelier’s principle
High temperature favour endothermic reaction therefore solubility will decrease with increases in temperature.
Vapour Pressure of liquid solution: –
-Vapour Pressure: The pressure exerted by vapour on the liquid surface at equilibrium is called vapour pressure.
- Vapour pressure of liquid-liquid solution:
– Raoult’s law for volatile liquid:
Volatile: – When it the liquid easily form vapour.
Composition in vapour phase:
PA = 𝛾A PT
𝛾A = PA/PT
𝛾A = PB/PT
Raoult’s Law of volatile liquid:
For a solution of volatile liquid, the partial vapour pressure of each component in the solution is directly proportion to its mole fraction present in the solution.
Liquid – liquid solution can be classified into ideal and non-ideal solution:
Ideal Solution: The solution which obey Raoult’s law over the entire range of concentration are known as ideal solution.
Properties of ideal solution: –
1. ∆mix H = 0
2. ∆mix V =0
– There is no change in enthalpy when two volatile liquid are mixed together.
-There is no change in volume when two volatile liquids are mixed together.
Condition to show: When intermolecular attraction between solvent-solvent and solute-solute is similar to solute-solvent. Example:
1. N- hex one on n- octone.
2. Bromoethane and chloroethane.
3. Benzene and toluene.
• Non-Ideal Solution:
The solution which does not obey Raoult’s Law is called non-ideal solution. The vapour pressure of such solution is either higher or lower than predicted by Raoult’s law.
– Solution showing positive deviation:
In this solution vapour pressure is more than predicted by Raoult’s law.
Properties of Positive deviation:
- ∆mix H > 0
Energy is observed by the solution.
2. ∆mix V > 0
Expansion of solution takes place.
(A-A, B-B) > (A-B)
Example: Ethanol and Acetone.
Mixture of ethanol and acetone is an example of positive deviation in pure ethanol molecules are hydrogen bonding on adding acetone molecules get in between the ethanol molecules breaks some of the H – bonding between them due to weakling of interaction the solution, show positive deviation from raoult’s law.
• Negative deviation: In this solution vapour pressure is less than predicted by
∆mix H < 0 (-ve)
Energy is released by the solution.
∆mixV < 0 (-ve)
Compression of solution takes place.
CONDITION: (A-A, B-B) < (A-B)
– Phenol and aniline.
– Chloroform and acetone (CHCl3)
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A mixture of chloroform and acetone form a solution with negative deviation from Raoult’s law this is because chloroform molecules able to form H-bond with acetone molecules this decrease the escaping tendency of the molecules and consequently the vapour decrease this resulting in negative deviation from Raoult’s law.
Azeotropes: These are binary mixture having the same composition of liquid and vapour phase boil at constant temperature. In such cases it is not possible to components by fractional distillation.
There are two types of azeotropes:
Minimum boiling azeotropes: The azeotrope in which boiling point of the mixture less than the boiling point of its component. The solution which a large positive deviation from Raoult’s law form minimum boiling azeotropes at us specific composition.
Ex:– ethanol (95%) water mixture (5%)
Maximum boiling azeotropes: The azeotropes in which boiling point of the mixture is more than the boiling point of its component.
The solution which show large negative deviation from Raoult’s law from maximum boiling azeotropes at specific composition.
– Nitric acid with water 393.5K boiling point.
Colligative Properties: The properties which depend on the number of solute particles is called colligative properties.
Psolvent – Psolution= Xsolute
Elevation of boiling point:
Boiling point: The temperature at which vapour pressure is equal to atmospheric pressure is called boiling point.
V.P = A.P
• Elevation of boiling point:
∆Tb = Tsolution – Tsolvent
(∆Tb α m; ∆Tb = kb × m)
w = given mass of solute
W = given mass of solvent
M = molar mass of solute
Kb = molar elevation constant Ebullioscopy constant.
S.I. unit of Kb = k.kg / mol.
Depression of Freezing Point:
Freezing point: The temperature at which the V.P of the substance in its liquid phase is equal to its V.P in the solid phase. V.P of liquid = V.P of solid.
Osmosis & Osmatic pressure:
- Osmosis pressure: The phenomena of moment of solvent particle from law concentration of solute to high conc. of solute through SPM is known as osmosis.
- Osmatic pressure: The excess pressure applied to solution side to stop the flow of solvent is called osmatic pressure
➢ Excess pressure (𝜋) = CRT (concentrate molarity)
𝜋 = n/v R
(𝜋) = W2 × RT / M2 × V
R = 0.083 L bar mol -1 K -1
Semi permeable membrane: It is only applicable to flow solvent water from low conc. to high conc.
- Isotonic Solution: Two solution having same osmatic pressure at a given temperature are called isotonic solution.
(NOTE- when two isotonic solution are separated by SPM number osmosis occurs between them).
E.g., 0.9% of sodium chloride solution in isotonic with fluid in blood cell.
- Hypotonic Solution: It has lower osmatic pressure than another solution. It has lower conc. of solute than another solution.
E.g., if the salts conc. is less than 0.9% than water will flow into the cell and they would swell.
- Hypertonic Solution: It refer to a solution with higher osmatic pressure than another solution. In other word a hypertonic solution is one, in which there is greater conc. the membrane than there are inside it.
E.g., if we place the blood cell in solution containing more than 0.9% NaCl solution water will flow out to the cell they shrink. Such a solution is called hypertonic solution.
-Reverse osmosis: When the pressure is more than osmatic pressure to the solution side the direction of osmosis is reverse this phenomenon is called reverse osmosis.
Application: Reverse osmosis is used in disclination of sea water.
Van’t Hoff factor (i):
I = no. of particle after dissociation/association / no. of particle before association/dissociation
Degree of dissociation (α)
α = i – 1 / n – 1
α = i – 1 / (1/n – 1)
0 < α ≤ 1
i = Normal molar mass/abnormal molar mass
(i)= observed colligative properties/calculative colligative properties.