All Laws and Theories class 12

12 Laws of Chemistry Class 12 – You Must Know

Hey, are you looking for all chemistry laws and theories in one PDF? then this article gives you what you want. Here we are discussing the main laws and theories of chemistry from the class 12 syllabus. 

Let’s started!

Henry’s Law: 

Statement of Henry’s law says that the solubility of any gases in water at constant temperature is directly proportional to the pressure of the gas above the solution.

Raoult’s Law: 

In all laws of chemistry, Raoult’s law is again important. Raoult’s law states that at a constant temperature the partial vapor pressure of a volatile component of a solution is equal to the product of vapor pressure of the pure component and their mole fractions of the component in the same solution. 

Van’t Hoff Law

Van’t Hoff Law is simple in your chemistry of class 12. 

According to this law, ‘ It states that the solubility of a gas in water at constant temperature is proportional to the pressure of the gas above the solution’ 

Van’t Hoff-Avogadro’s Law

Van’t Hoff-Avogadro’s law stated that, At the given temperature, equal volumes of the solutions having the same osmotic pressure contain an equal number of solute particles.

Thermodynamics first law

From the laws and theories class 12 thermodynamics again useful and simple laws. They have very important role in chemistry as well as physics.

Statement 1: 

The energy can not be generated either destroyed, it can only be transformed from one kind to a different form of energy.

In another way also we can state the Thermodynamic First Law

 Statement 2: 

Whenever a quantity of one kind of energy is consumed or disappears, an equivalent amount of another form of energy appears. 

The first law of thermodynamics (mathematical statement)

We will understand with the mathematical statement as below,



∆U = change in internal energy

 q = Heat absorbed

 W = Work performed

Hess’s Law of constant heat summation

Hess’s Law of constant heat summation states that the heat of a reaction or the enthalpy difference in a chemical reaction depends upon the initial phase of reactants and final state of products and free of the path by which that reaction is brought about (in the single-step or series of steps)

The second law of thermodynamics

We know the all-natural processes are spontaneous, they are taking place with an increase in enthalpy.

Therefore, the second law o thermodynamics can be represented mathematically as, 

Third law of thermodynamics

The third law of thermodynamics states that the entropy of a pure and perfectly ordered crystalline substance is zero at absolute zero (i.e. 0 K) temperature.

Hence, at 0 K, for pure crystalline substance, S = 0

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Kohlrausch’s law of independent migration of ions

 This states that, at infinite dilution of the solution, each ion of an electrolyte migrates independently of its co-ions and contributes independently to the total molar conductivity of the electrolyte, irrespective of the nature of other ions present in the solution.

Faraday’s First Law of Electrolysis

Faraday’s first law of electrolysis said that the amount of the substance generated due to oxidation or reduction at the electrode during electrolysis proportional to the quality of electricity that carries within the electrolytic cell.

Faraday’s 2nd Law of Electrolysis

According to Faraday’s second law of electrolysis, when the same quantity of electricity is transferred through different electrolytic cells carrying different electrolytes, designed in series, then the amounts of the substances produced by oxidation or reduction at the respective electrodes are directly proportional to their respective chemical equivalent mass.

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