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NCERT Solutions for Class 11 Chemistry Chapter 6 Equilibrium

NCERT Solutions for Class 11 Chemistry Chapter 6 Equilibrium covers equilibrium in physical and chemical processes, the law of chemical equilibrium and equilibrium constant, factors affecting equilibrium (Le Chatelier's Principle), and ionic equilibrium including acids, bases, and pH.

Overview of Topics & Subtopics (Click to Jump)

1. Equilibrium in Physical and Chemical Processes

Short Note:

• A state of dynamic equilibrium is reached when the rate of the forward reaction equals the rate of the backward reaction, and concentrations of reactants and products remain constant over time.

2. Law of Chemical Equilibrium and Equilibrium Constant

Short Note:

• For a reaction aA + bB ⇌ cC + dD, the equilibrium constant Kc = [C]c[D]d / [A]a[B]b, and Kp is the corresponding expression using partial pressures.

• A large K value indicates the reaction favours products at equilibrium; a small K value indicates it favours reactants.

3. Le Chatelier's Principle

Short Note:

• If a system at equilibrium is subjected to a change in concentration, pressure, volume, or temperature, the equilibrium shifts in the direction that tends to counteract the effect of the change.

4. Ionic Equilibrium: Acids, Bases and pH

Short Note:

• Arrhenius, Bronsted-Lowry, and Lewis concepts define acids and bases in increasingly general terms (Lewis acid = electron pair acceptor, Lewis base = electron pair donor).

• pH = −log[H+]; pH + pOH = 14 (at 25°C). Ionic product of water, Kw = [H+][OH−] = 10−14 at 25°C.

• Common Ion Effect and the Solubility Product (Ksp) govern the equilibrium of sparingly soluble ionic compounds in solution.

NCERT Textbook Exercise Questions

For the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), write the expression for Kc.
Answer: Kc = [NH3]² / ([N2][H2]³).
The equilibrium constant for a reaction is 10. What will be the equilibrium constant for the reverse reaction?
Answer: The equilibrium constant of the reverse reaction is the reciprocal of the forward reaction's constant: K'c = 1/Kc = 1/10 = 0.1.
What will be the effect of an increase in pressure on the equilibrium N2(g) + 3H2(g) ⇌ 2NH3(g)?
Answer: According to Le Chatelier's Principle, increasing pressure shifts equilibrium towards the side with fewer moles of gas. Here, reactants have 4 moles of gas and products have 2 moles, so the equilibrium shifts forward (towards NH3 formation).
Calculate the pH of a solution whose hydrogen ion concentration is 3.8 × 10−3 M.
Answer: pH = −log(3.8 × 10−3) = −(log 3.8 + log 10−3) = −(0.58 − 3) = 2.42.
The Ksp of AgCl is 1.8 × 10−10. Calculate its solubility in mol/L.
Answer: AgCl ⇌ Ag+ + Cl−. Ksp = [Ag+][Cl−] = s² = 1.8 × 10−10. So s = √(1.8×10−10) ≈ 1.34 × 10−5 mol/L.
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Class 11 › Chemistry › Equilibrium
Chapter notesRead the chapterPractice MCQsCheck what you rememberChapter test10 questions on one pageOnline testTest 1, 2 and 3, one question at a timePYQPrevious year questionsStudy materialPDF notes
Topics in this chapter: Equilibrium in Physical & Chemical Processes and Dynamic NatureLaw of Mass Action & Equilibrium Constants (K c and K p )Factors Affecting Equilibrium – Le Chatelier's PrincipleIonic Equilibrium: Acids, Bases, pH, Buffers & Solubility Product (K sp )