The JEE Exam 2025 is one of the most challenging and competitive exams for aspiring engineering students in India. A strong foundation in Chemistry plays a crucial role in securing a top rank. To help students streamline their preparation, mastering key chemistry formulas is essential.
In this guide, we will cover the most important chemistry formulas for JEE 2025, focusing on critical topics from Physical Chemistry, Organic Chemistry, and Inorganic Chemistry. By understanding and memorizing these formulas, students can boost their problem-solving skills and improve their chances of success in the exam.
A. Chemical equilibrium or the law of mass action
In a state of balance,
rf = rb, that is,
forward response rate = backward reaction rate
(C)x (D)y / (A)a (B)b = Keq or Kc
Where Kc = kf / kb.
Where “molar concentration” is indicated by braces and powers.
B. Equilibrium Constant in Partial Pressure Equation
Kp = (Pcm¹)(Pdm²) /( pan¹)(pbn²)
The partial pressure equilibrium constant is Kp.
C. Relationship of Kp and Kc expression
Kp = Kc (RT)Δn
n is the total number of molecules in the product – the total number of molecules in the reactants, and R is the gas constant of 0.0821 litres. atm/degree/mole.
D. The Equilibrium Constant and Standard Free Energy Relationship
ΔGo = – RT ln Keq or, ΔGo = – 2.303RT log Keq
E. Reaction Quotient Formula (Q)
The reaction quotient has the same algebraic formula as Keq, however, it is calculated using current concentrations rather than equilibrium concentrations.
Q has the following expression:
Q= (C)c (D)d/ (A)a (B)b
F. Dissociation Formula
The degree of dissociation (a) is calculated as the number of molecules dissociated divided by the total number of molecules taken.
K(diss): K(diss) is the dissociation constant.
K(diss) = (alpha)² . C/ (1- alpha) mol dm –³
A. Ostwald Dilution Law Formula
The law of chemical equilibrium, according to Ostwald, also applies to ionic equilibrium.
K = Ca.Ca / C (1-a)
The letter a represents the alpha symbol.
B. Buffer Capacity Representation Formula
Number of moles of acid/base added to UL of solution/change in pH = buffer capacity
C. The Solubility Formula
The weight of the solute in grams present in 100mL of solvent is referred to as solubility. It is represented by the letter s and is measured in moles per liter or grams per liter.
Solubility (s) = 1 / The number of common ions or the concentration of common ions.
A. EMF of a cell formula
EºCell = (standard cathode reduction potential) – (standard reduction potential of anode)
Eº Cell = Eº Cathode – Eº Anode = EºRight – Eº Left
B. Gibbs Free Energy Change Formula
In an electrochemical process, the Gibbs free energy change can be represented as the potential difference.
– Del G = nEF
A. Concentration of a Solution Formula
Concentration = Solute Quantity / Solution Volume
B. Vapour Pressure Relative Lowering Formula
It’s the ratio of reduced vapour pressure to pure solvent vapour pressure.
The relative reduction in vapour pressure is provided by,
= PAº -p / paº
Simply memorizing the formulae is insufficient; you will not be able to use these formulas unless and until your notions are clear. Furthermore, without practice, you are almost certain to forget the formulae or become confused about which formula to employ while completing the test paper.
The Joint Entrance Examination (JEE) is an examination that which candidates can benefit from the following key formulae in a number of ways: It contributes to exam time savings. It simplifies the math. Errors are less likely to occur.