Solutions Notes Class 12


Solutions Notes Class 12

Solutions Notes Class 12 Class 12 Solution NotesIf you are looking for easy NCERT Class 12 Solutions Notes then this is the the right place for Class 12th Solutions chemistry CBSE  you can learn NCERT Solutions Notes here without paying any thing for NCERT Solutions Chemsitry Solutions  Notes or Chemistry Solutions Notes for Class 12 , Chemistry Solutions Notes for class 12

Definition– Solution are homogeneous mixture of two or more than two components

Composition of solution

The substance constituting the solution are called the solution. As a generalization, the component present in smaller amount is called solute and the other present in larger amount is called solvent.

Different types of solution have solvent and solute in same or different phases. Solute is dissolved in the solvent. In a solution of carbon dioxide in water, as solvent and carbon dioxide acts as solute.

Notes on solutions

Unit of concentration

Molarity (M) – At a definite temperature, m per litre of solution is known as molarity of solution at that temperature. Unit of molarity is mol L-10.

Solutions Notes Class 12

Molality (m) – Number of moles of solute dissolved in 1000 g of solvent is known as molality. Unit of molality is mol/kg .

Solutions Notes Class 12

Solutions Class 12 Notes Chemistry

Normality(N)– At a definite amount of gram equivalent of solute dissolved in 1 l of solution is known as normality of solution at that temperature. 10th unit is gram equivalent per litre.


Mole fraction– It is the number of moles of one component to the total number of moles of all components present in solution.

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Parts per million– When a solute is present in trace quantities, the concentration is expressed in the parts per million.

Solutions Notes Class 12

Mass percent– The mass percentage of a component in a given solution is the mass of the component per 100 gram of the solution.

Volume per cent (V/V) – The volume percentage is the volume of the component per 100 parts by volume of the solution.

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Solubility– It is the maximum amount that can be dissolved in a specified amount of solvent at a specified temperature it depends on nature of solute, solvent, temperature and pressure.

Solubility of solid in liquid– Solids are soluble in a liquid if there intermolecular interaction are similar.  The solubility of a solid in a liquid at any temperature is defined as the maximum amount of the solid in gram which can be dissolved in hundred gram of the liquid to form the saturated solution at that particular temperature.

Solubility of a gas in a liquid – Almost all gases are soluble in water though to different extent. The solubility of any gas in a particular liquid is the volume of the gas in cubic centimetre, that can be dissolved in unit volume ICC of the liquid to form the saturated solution at certain temperature and under a pressure of 1 atmosphere.

Solid solutions – an alloy or solid solution is a solution of two or more metals or a metals with one or more non metals.

Henry’s law– Henry was the first one to give a quantitative relation between pressure and solubility of gas in a solvent which is called Henry’s law. At a constant temperature, the solubility of gas in a liquid is directly ∝ to the partial pressure of the gas present above the surface of liquid or solution.

S ∝ P or S = KHp      (unit of solubility is same as concentration).

Applications of Henry’s law –

  1. To increase the solubility of carbon dioxide in soft drinks and soda water, is sealed under high pressure
  2. To avoid bends and the toxic effect of high concentration of N2in the blood, the buy Scuba driver are filled with air diluted with He.

Raoult’ law– In this law the pressure of any component, is product of its mole fraction and vapour pressure of the component in pure state (p°). Solution of volatile matters at a particular temperature, partial pressure of each component p°A or p°B is equal to the product of partial pressure of that component in pure state [p°A & p°B ] and mole fraction of that component in solution [XA and XB]. Thus,                  ps=P°A XA+P°B XB

Colligative properties– Those properties of solution which depends only upon the number of particles of solute dissolved in unknown volume of a given solvent and not upon the nature of solute are known as colligative properties.

Relative lowering of vapour pressure– Ratio of lowering pressure of solvent and vapour pressure of pure solvent is known as relative lowering of vapour pressure. According to Raoult’s law, lowering of vapour pressure due to mixing of non-volatile solute matters is equal to mole fraction of solute in solution (Xsolute).

Class 12th SolutionsElevation in boiling point– Boiling point of a liquid is that temperature which its vapour pressure becomes same to the atmospheric pressure. If T°b is boiling point of pure solvent and T°b is the boiling point of solution, then the elevation is boiling point is represented as,  Tb= Tb – T°b

Solutions Notes Class 12

Relationship between elevation in boiling point and molalityClass 12th Solutions

Molal elevation constant (Kb)

The increase in boiling point on dissolving 1 mol of solute in 1000 g of solvent is known as molal elevation constant. The value of molal elevation constant is fixied for a particular solvent, irrespective of solute is used. This is because one mole of any substance is dissolved in a solvent, the number of particles obtained is always fixed.

Solutions Notes Class 12

Depression in freezing point

At freezing point, the vapour pressure of liquid and solid state is equal. When any solute is dissolved in solvent, then freezing point solvent gets lowered down. This lowering of freezing point is known as depression of freezing point.

Solutions Notes Class 12

Osmosis and Osmotic pressure (p or Π)

The phenomenon in which solvent passes through a semipermeable membrane separating pure solvent and solution from the side of pure solvent to the solution is known as osmosis.

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The excess pressure which must be applied to a solution to prevent the passage of solvent into it through the semipermeable membrane is called osmotic pressure.

Isotonic solution– Isotonic solution are those solution which have 2 solutions having same osmotic pressure at a given temperature are called isotonic solutions.

Hypotonic– A solution having lower osmotic pressure than the other solution is called hypotonic while the one with higher osmotic pressure is called hypertonic.

Van’t Hoff Factor (i) – van’t Hoff introduced a factor ‘i’, known as van’t Hoff factor i. It is the ratio b/w the real concentration of particles produced, when the substance is dissolved and the concentration of substance as calculated from its mass.

Van’t Hoff factor (i) =\frac { observed\quad value\quad of\quad colligative\quad property }{ calculated\quad value\quad of\quad colligative\quad property }

For electrolyte, i > 1, substance which get associated in solution, i < 1 and when there is no dissociation i = 1

Thus, introduction of van’t Hoff factor modifies the equation of colligative properties as follows-

Solutions Notes Class 12

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