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Chapter Analysis
Intermediate40 pages • EnglishQuick Summary
The chapter on Equilibrium for Class 11 Chemistry Part 1 covers the dynamic nature of equilibrium in chemical and physical processes. It discusses the law of chemical equilibrium and introduces equilibrium constants (Kc and Kp) along with the reaction quotient (Qc). The chapter also elaborates on factors affecting equilibrium such as concentration, temperature, pressure, and the addition of inert gases, applying Le Chatelier's Principle. Additionally, it explains various concepts like acids and bases, ionization, pH, buffer solutions, solubility product, and equilibrium in ionic solutions.
Key Topics
- •Dynamic Equilibrium
- •Le Chatelier's Principle
- •Equilibrium Constants (Kc and Kp)
- •Reaction Quotient (Qc)
- •Acid-Base Equilibrium
- •Ionization and pH
- •Buffer Solutions
- •Solubility Product
Learning Objectives
- ✓Identify the dynamic nature of chemical and physical equilibrium.
- ✓Apply the law of chemical equilibrium and calculate equilibrium constants.
- ✓Predict the effects of changing conditions using Le Chatelier's Principle.
- ✓Classify substances using Arrhenius, Bronsted-Lowry, and Lewis concepts.
- ✓Calculate and understand the significance of pH and buffer solutions.
- ✓Use the solubility product to predict solubility and precipitation reactions.
Questions in Chapter
A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased. What is the initial effect of the change on vapour pressure? How do rates of evaporation and condensation change initially? What happens when equilibrium is restored finally and what will be the final vapour pressure?
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What is Kc for the following equilibrium when the equilibrium concentration of each substance is: [SO2]= 0.60M, [O2] = 0.82M and [SO3] = 1.90M?
Page 210
At 1127 K and 1 atm pressure, a gaseous mixture of CO and CO2 in equilibrium with solid carbon has 90.55% CO by mass. Calculate Kc for this reaction at the above temperature.
Page 211
Calculate a) ∆G⁰ and b) the equilibrium constant for the formation of NO2 from NO and O2 at 298K.
Page 211
Does the number of moles of reaction products increase, decrease, or remain same when each of the following equilibria is subjected to a decrease in pressure by increasing the volume?
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Which of the following reactions will get affected by increasing the pressure? Also, mention whether change will cause the reaction to go into forward or backward direction.
Page 211
The equilibrium constant for the following reaction is 1.6 ×105 at 1024K. H2(g) + Br2(g) --> 2HBr(g). Find the equilibrium pressure of all gases if 10.0 bar of HBr is introduced into a sealed container at 1024K.
Page 211
Dihydrogen gas is obtained from natural gas by partial oxidation with steam as per following endothermic reaction: CH4 (g) + H2O (g) --> CO (g) + 3H2 (g). (a) Write as expression for Kp for the above reaction. (b) How will the values of Kp and composition of equilibrium mixture be affected by (i) increasing the pressure (ii) increasing the temperature (iii) using a catalyst?
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Describe the effect of: addition of H2, addition of CH3OH, removal of CO, removal of CH3OH on the equilibrium of the reaction: 2H2(g) + CO (g) --> CH3OH (g).
Page 211
Additional Practice Questions
Explain how Le Chatelier’s principle is used to predict the effect of pressure changes on a chemical reaction at equilibrium.
mediumAnswer: Le Chatelier's principle states that if an external pressure is applied to a system at equilibrium, the system adjusts in a way that counteracts the change. For example, increasing pressure will favor the reaction direction that produces fewer gas molecules, thus reducing the pressure.
What is the significance of the equilibrium constant (Kc) in a chemical reaction?
easyAnswer: The equilibrium constant, Kc, signifies the ratio of product concentrations to reactant concentrations at equilibrium. A large Kc indicates that the reaction favors products, while a small Kc suggests reactants are favored. It is specific to a particular reaction at a given temperature.
Illustrate with an example how temperature affects the equilibrium constant of an exothermic reaction.
mediumAnswer: For an exothermic reaction, the equilibrium constant decreases with an increase in temperature. Consider the Haber process for ammonia synthesis: N2(g) + 3H2(g) ⟷ 2NH3(g). Here, increasing temperature shifts the equilibrium back towards reactants (N2 and H2), reducing the equilibrium constant.
Define the concept of dynamic equilibrium in a chemical reaction and provide an example.
mediumAnswer: Dynamic equilibrium occurs when the rate of the forward reaction equals the rate of the reverse reaction, resulting in no net change in concentrations of reactants and products. An example is the synthesis of water: H2(g) + O2(g) ⟷ 2H2O(g), where both the forward and reverse reactions occur at equal rates.
How do catalysts affect chemical equilibrium?
easyAnswer: Catalysts do not affect the position of chemical equilibrium; they increase the rate at which equilibrium is achieved by lowering the activation energy, thus speeding up both forward and reverse reactions equally.
What role does the reaction quotient (Qc) play in determining the direction of a reaction at non-equilibrium conditions?
mediumAnswer: The reaction quotient, Qc, helps predict the direction of a reaction. If Qc < Kc, the reaction will proceed forward to create more products. If Qc > Kc, the reaction will shift backward to form more reactants until equilibrium is achieved.