Important Chemistry Formulas For JEE
Chemistry forms a critical part of the Joint Entrance Examination (JEE) and having a solid foundation in key formulas is essential to excel in this subject. Whether you're aiming to clear JEE Main or JEE Advanced, understanding and applying these formulas can make a significant difference in your performance. In this article, we'll explore the essential chemistry formulas for JEE and highlight their significance in your preparation.
Chemistry stands out as a highly promising and rewarding subject within the IIT JEE curriculum. As the final days of preparation approach, it becomes crucial to swiftly revise all the vital chemistry formulas. Hence, provided below are essential chemistry formulas organized by topic for your convenience.
Important Formulas of Chemistry : Table View
No. |
Topic |
Formulas |
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1 |
Chemical Equilibrium |
A. Law of mass action: rf = rb, Keq = (C)^x (D)^y / (A)^a (B)^b. B. Kp = (Pcm1)(Pdm2) / (pan1)(pbn2). C. Kx = XcC XdD / XaA XbB. D. Kp = Kc (RT)Δn. E. ΔGo = – RT ln Keq. F. Q = (C)c (D)d/ (A)a (B)b. G. Degree of dissociation (ɑ), K(diss). |
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Ionic Equilibrium |
A. Ostwald Dilution Law, K = (A)+ (B)- / (AB) = Ca.Ca / C (1-a). B. Buffer Capacity. C. Solubility, Solubility (s). D. Solubility Product, Ksp. |
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3 |
Electrochemistry |
A. EMF of cell, E0Cell = (E0 Cathode) - (E0 Anode). B. Nernst Equation. C. Gibbs Free Energy Change. D. Concentration Cell. |
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Solutions and Colligative Prop. |
A. Concentration of a Solution. B. Relative Lowering of Vapour Pressure. C. Raoult’s Law. D. Elevation of Boiling Point. E. Freezing Point Depression. |
Important Formulas of Chemistry are Given below Topic-Wise
1. Formulas for Chemical Equilibrium
A. Law of mass action or chemical equilibrium
At equilibrium Condition,
rf = rb, i.e.,
rate of forward reaction = rate of backward reaction
Keq or Kc = (C)x (D)y / (A)a (B)b
Where, Kc = kf / kb
Where the braces and powers are used to indicate “molar concentration”.
B. Formula for Equilibrium Constant in terms of Partial Pressure
Kp = (Pcm1)(Pdm2) /( pan1)(pbn2)
Where Kp is equilibrium constant in terms of partial pressure.
C. Formula for Equilibrium Constant in terms of Mole Fraction
Kx = XcC XdD / XaA XbB
Where Kx is the equilibrium constant in terms of mole fraction.
D. Expression for Relation between Kp and Kc
Kp = Kc (RT)Δn
where R is gas constant 0.0821 liters.atm/degree/mole and Δn is the total number of molecules of the product – the total number of molecules of the reactants.
E. Relation between Equilibrium Constant and Standard Free Energy
ΔGo = – RT ln Keq
or,
ΔGo = – 2.303RT log Keq
F. Formula for Reaction Quotient (Q)
The reaction quotient has the same algebraic formula as Keq but the current concentrations instead of specifically the equilibrium concentrations are used in calculations.
The expression for Q is
Q = (C)c (D)d/ (A)a (B)b
G. Formula for Degree of Dissociation
Degree of dissociation (ɑ) = No. of molecules dissociated/Total no.of molecules taken.
Dissociation constant, K(diss):
Kdiss = (alpha)2 . C/ (1- alpha) mol dm-3
2. Formula for Ionic Equilibrium
A. Formula for Ostwald Dilution Law
Ostwald pointed out that the law of chemical equilibrium is applicable to ionic equilibrium.
K = (A)+ (B)- / (AB) = Ca.Ca / C (1-a)
Here a denotes alpha sign.
B. Formula for Representing Buffer Capacity
Buffer Capacity = Number of moles of acid/ Base added to UL of solution/change in pH
C. Formula for Solubility
Solubility is the weight of solute in grams present in 100ml of solvent. It is denoted by s and is expressed in mole per litre or gram per litre.
Solubility (s) = 1 / Concentration of common ions or number of common ions
D. Formula for Solubility Product
The solubility product constant Ksp is the equilibrium constant for the equilibrium established between a slightly soluble ionic compound and its ions in a saturated aqueous solution.
Ksp = (Xs)x. (Ys)y = Xx.Yy.(S)x+y
3. Formulas on Electrochemistry
A. Formula for EMF of cell
E0Cell = (standard reduction potential of cathode) - (standard reduction potential of anode)
E0 Cell = E0 Cathode - E0 Anode = E0 Right - E0 Left
B. Formula for Nernst Equation
Dependence of electrode potential and EMF on concentration and temperature.
For electrode potential:
Mn+ + ne- ------- M(s)
E = E0 RT In M(s) / nF (Mn+)aq
C. Formula for Gibbs Free Energy Change
Gibbs free energy change in an electrochemical reaction can be expressed as the equivalent of the potential difference.
- Del G = nEF
D. Formula for Concentration Cell
E cell = -( 0.0592/2) log (a2/ a1)
E0 cell = 0
4. Formula on Solutions and Colligative Property
A. Formula for Concentration of a Solution
Concentration = Quantity of Solute / Volume of Solution
B. Formula For Relative Lowering of Vapour Pressure
It is the ratio of lowering of vapour pressure to the vapour pressure of pure solvent.
Relative lowering of vapour pressure is given by,
= PA0 -p / pa0
C. Formula for Raoult’s Law
The vapour pressure of a solution is equal to the product of a mole fraction of the solvent and its vapour pressure in the pure state.
P / pA = (1-XB)
Where xA+xB = 1, therefore xA= 1-xB
D. Formula For Elevation of Boiling Point
Boiling point elevation = Tb - Tb0
Tb = Kb M.m /1000
E. Formula for Freezing Point Depression
Freezing point depression = Tf0 - Tf
Key Formulas for JEE Chemistry:
Physical Chemistry:
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Ideal Gas Law (PV = nRT): This formula relates the pressure, volume, amount of gas, and temperature of an ideal gas.
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Nernst Equation (E = E° - (0.0592/n) * log(Q)): It's used to calculate the cell potential of an electrochemical cell under non-standard conditions.
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Rate Law (rate = k[A]^m[B]^n): This formula quantifies the relationship between reaction rate and the concentrations of reactants.
Organic Chemistry:
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SN1 and SN2 Reactions: These formulas explain the mechanisms of nucleophilic substitution reactions.
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E1 and E2 Reactions: They describe the mechanisms of elimination reactions.
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Functional Group Transformations: Understanding reagents and conditions for various functional group transformations is essential.
Inorganic Chemistry:
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Ionization Energy Trends: The trend of ionization energy across the periodic table follows specific patterns.
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Electron Affinity Trends: Similar to ionization energy, electron affinity also follows trends across elements.
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Solubility Product (Ksp): This formula helps determine the solubility of salts in solution.
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Redox Reactions: Balancing redox reactions and understanding oxidation states are crucial.
Applying Formulas Effectively
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Conceptual Understanding: Don't just memorize formulas; understand the concepts behind them. This makes it easier to apply them to different scenarios.
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Practice Extensively: Solving a variety of problems is key to becoming comfortable with using formulas. JEE-level problems and previous years' question papers are valuable resources.
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Use of Units: Always pay attention to units when applying formulas. Inaccurate units can lead to incorrect answers.
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Derivations: If time allows, understanding the derivation of a formula can provide deeper insights into its application.
Mastering important chemistry formulas is a significant step towards achieving success in JEE. However, remember that formulas are just one part of the puzzle; understanding the concepts and their applications is equally important. Approach your preparation with a balance of theoretical understanding and practical application, and you'll be well-equipped to tackle the chemistry section of the JEE with confidence.
Important Chemistry Formulas For JEE FAQs
Q1. What are the key chemistry formulas for JEE?
Ans. Essential chemistry formulas encompass various topics, including fundamental equations like the ideal gas law, Nernst equation, equilibrium constants, and reaction rate formulas.
Q2. Which chapter is challenging in JEE chemistry?
Ans. The difficulty perception varies, but "Organic Chemistry" and "Chemical Bonding" are often tough for JEE due to intricate concepts and numerous reactions.
Q3. Is NCERT sufficient for IIT chemistry?
Ans. While NCERT builds a foundation, additional resources like specialized JEE chemistry books are recommended for comprehensive IIT JEE preparation.
Q4. Which chemistry topic scores well in JEE mains?
Ans. Generally, topics like "Chemical Bonding," "Coordination Compounds," "Ionic Equilibrium," and "Thermodynamics" are more scoring due to direct and conceptual questions.
Q5. What rank is 99.5 in JEE Mains?
Ans. A JEE Mains score of 99.5 percentile generally signifies a top 0.5% ranking among test-takers, but the specific rank varies yearly.
