Given the reaction $$NH_3 + H_2O \rightleftharpoons NH_4^+ + OH^-$$, if the $pK_b$ of $NH_3$ is 4.75, what can be inferred about the strength of $NH_3$ as a base?

$NH_3$ is neither strong nor weak.

The strength of $NH_3$ cannot be determined from $pK_b$.

In the equilibrium reaction $$CaCO_3(s) \rightleftharpoons CaO(s) + CO_2(g)$$, what will be the effect on the equilibrium position if the pressure is increased by adding an inert gas at constant volume?

The equilibrium will remain unchanged.

The equilibrium will shift to the right.

The equilibrium will shift to the left.

The equilibrium will remain unchanged.

The equilibrium constant will increase.

Which of the following statements is true regarding the Lewis concept of acids and bases?

A Lewis acid is a substance that can accept a pair of electrons.

A Lewis acid is a substance that can donate a pair of electrons.

A Lewis base is a substance that can accept a pair of electrons.

A Lewis acid is a substance that can accept a pair of electrons.

A Lewis base is a substance that can donate a proton.

In a closed system at equilibrium, what happens to the equilibrium position when the concentration of a reactant is increased?

The equilibrium shifts to the right to produce more products.

The equilibrium shifts to the left to produce more reactants.

The equilibrium remains unchanged.

The equilibrium shifts randomly.

Considering the reaction $2NO_2(g) \rightarrow N_2O_4(g)$, which is exothermic, how will an increase in temperature affect the equilibrium constant $K_c$?

The equilibrium constant $K_c$ will decrease.

The equilibrium constant $K_c$ will increase.

The equilibrium constant $K_c$ will decrease.

The equilibrium constant $K_c$ will remain unchanged.

The reaction will become non-spontaneous.

StudyTunnel

by BhamuIntelli Systems LLP

StudyTunnel

Loading content...

Equilibrium

Notes Questions Mock-Test

Learning Objectives

Top

Learning Objectives

Understand the dynamic nature of chemical equilibrium and how it is established when the rate of the forward reaction equals the rate of the reverse reaction.
Apply the law of mass action to write equilibrium constant expressions for various chemical reactions.
Calculate equilibrium constants ( $K_c$ and $K_p$ ) and understand their dependence on stoichiometric coefficients.
Predict the effects of changes in concentration, pressure, and temperature on the position of equilibrium using Le Chatelier's Principle.
Analyze the temperature dependence of equilibrium constants and how it affects the direction of exothermic and endothermic reactions.
Explore heterogeneous equilibria involving multiple phases and understand the exclusion of pure solids and liquids in equilibrium constant expressions.
Use the reaction quotient ( $Q_c$ ) to predict the direction of reaction shifts to reach equilibrium.
Relate Gibbs free energy change ( $\Delta G$ ) to the equilibrium constant to determine reaction spontaneity.
Investigate equilibrium in physical processes, such as phase changes and solubility, including the application of Henry's law.
Utilize equilibrium constants to predict the extent of reactions, direction of reaction shifts, and calculate equilibrium concentrations from initial data.
Classify acids and bases using Arrhenius, Bronsted-Lowry, and Lewis concepts, and calculate ionization constants for weak acids and bases.
Explain the ionization of water, the ionic product ( $K_w$ ), and the relationship between $pH$ and $pOH$ .
Evaluate the strength of acids and bases using $pK_a$ and $pK_b$ values.
Understand the function and calculations related to buffer solutions and their resistance to $pH$ changes.

Practice, Analyze & Improve 🚀

Dont just read—test your knowledge! Unlock the Student Workspace to take chapter tests and get instant performance insights.

Deep Analytics

Peer Comparison

Track Progress

Claim Free Account100% Free • No credit card required

Revision Notes & Summary

Top

Chapter Notes

Dynamic Chemical Equilibrium

Definition: A state where the rate of the forward reaction equals the rate of the reverse reaction, resulting in constant concentrations of reactants and products.
Dynamic Nature: At equilibrium, reactions continue to occur at the molecular level, but no net change is observed in the concentrations.
Law of Mass Action: The rate of a chemical reaction is proportional to the product of the masses of the reacting substances, each raised to a power equal to the coefficient in the balanced chemical equation.

Equilibrium Constant Expressions

Kc: Equilibrium constant in terms of concentration.
Kp: Equilibrium constant in terms of partial pressures.
Expression: For a reaction $aA + bB \rightleftharpoons cC + dD$ , the equilibrium constant is given by: $K_c = \frac{[C]^c[D]^d}{[A]^a[B]^b}$
Dependence on Stoichiometry: The powers in the expression are the stoichiometric coefficients from the balanced equation.

Le Chatelier's Principle

Principle: If a system at equilibrium is subjected to a change in concentration, pressure, or temperature, the system will adjust to counteract the effect of the change and a new equilibrium will be established.
Concentration: Adding a reactant or product shifts the equilibrium to consume the added substance.
Pressure: Increasing pressure shifts the equilibrium towards the side with fewer moles of gas.
Temperature: Increasing temperature favors the endothermic direction.

Temperature Dependence of Equilibrium

Exothermic Reactions: Increase in temperature decreases $K$ .
Endothermic Reactions: Increase in temperature increases $K$ .

Heterogeneous Equilibria

Definition: Equilibria involving more than one phase.
Expression: Pure solids and liquids do not appear in the equilibrium constant expression.

Reaction Quotient (Qc)

Definition: A ratio similar to the equilibrium constant but for non-equilibrium conditions.
Use: Predicts the direction of the reaction shift to reach equilibrium by comparing $Q_c$ with $K_c$ .

Gibbs Free Energy and Equilibrium

Relationship: $\Delta G = \Delta G^\circ + RT \ln Q$
Equilibrium: At equilibrium, $\Delta G = 0$ and $Q = K$ , so $\Delta G^\circ = -RT \ln K$ .

Equilibrium in Physical Processes

Examples: Solid-liquid, liquid-vapour, solid-vapour, solid-in-liquid, and gas-in-liquid equilibria.
Vapour Pressure: At equilibrium, the vapour pressure is constant.

Applications of Equilibrium Constant

Extent of Reaction: Large $K$ indicates products predominate; small $K$ indicates reactants predominate.
Direction: Compare $Q$ with $K$ to predict the direction of the reaction.
Equilibrium Concentrations: Calculate using initial concentrations and $K$ .

Acids and Bases: Arrhenius, Bronsted-Lowry and Lewis Concepts

Arrhenius: Acids produce $H^+$ in water, bases produce $OH^-$ .
Bronsted-Lowry: Acids are proton donors, bases are proton acceptors.
Lewis: Acids accept electron pairs, bases donate electron pairs.

Ionisation Constants of Weak Acids and Weak Bases

Ka and Kb: Measure the strength of weak acids and bases.
Ostwald's Dilution Law: Relates degree of ionization to concentration.

Ionisation of Water, Kw, pH and pOH

Kw: Ionic product of water, $Kw = [H^+][OH^-]$ .
pH and pOH: $pH + pOH = pKw$ .

pKa, pKb and Strength of Acids/Bases

Relation: $pKa = -\log Ka$ , $pKb = -\log Kb$ .
Strength: Lower $pKa$ or $pKb$ indicates stronger acid or base.

Buffer Solutions

Definition: Solutions that resist changes in pH upon addition of small amounts of acid or base.
Components: Typically consist of a weak acid and its conjugate base or a weak base and its conjugate acid.

Do you belong in the Top 10%?

Our analytics show that most students struggle with specific concepts in Equilibrium. Take a free diagnostic test to generate your personal Learning DNA profile.

Practice Test – MCQs, True/False

Top

Multiple Choice Questions

Increasing the pressure

Decreasing the temperature

Removing

NH_3

as it forms

Adding an inert gas at constant volume

Correct Answer: A

Solution:

Increasing the pressure shifts the equilibrium to the right because it reduces the total number of moles of gas, favoring the formation of

NH_3

Chapter Concept:

Dynamic Chemical Equilibrium

Increasing the temperature

Decreasing the pressure

Increasing the pressure

Adding an inert gas at constant volume

Correct Answer: C

Solution:

Increasing the pressure will favor the formation of ammonia because the reaction results in a decrease in the number of gas molecules, shifting the equilibrium towards the products.

Chapter Concept:

Acids and Bases: Arrhenius, Bronsted-Lowry and Lewis Concepts

Experience the StudyTunnel Method

We do not just give you mock tests. We guide you through a gamified, AI-driven learning path designed to guarantee mastery.

Step 1: Practicing the Concepts

Equilibrium

Step 2: Master Boss Exam

Locked • Full Phase Assessment

Step 3: Redemption Arena

Locked • AI Weakness Tracker

True or False

Correct Answer: True

Solution:

The Bronsted-Lowry concept defines an acid as a proton donor.

Chapter Concept :

Acids and Bases: Arrhenius, Bronsted-Lowry and Lewis Concepts

Correct Answer: True

Solution:

The equilibrium constant

K_c

is a characteristic of the reaction at a given temperature and does not depend on the initial concentrations of reactants and products.

Chapter Concept :

Equilibrium in Physical Processes

Correct Answer: True

Solution:

The equilibrium constant expression is derived from the balanced chemical equation, where the concentrations of the products are raised to the power of their stoichiometric coefficients and divided by the concentrations of the reactants raised to the power of their stoichiometric coefficients.

AI Learning Assistant

StudyTunnel Methodology

1

Master the Concepts

2

Conquer Boss Exams

3

The Redemption Arena

Equilibrium

Learning Objectives

Learning Objectives

Practice, Analyze & Improve 🚀

Revision Notes & Summary

Chapter Notes

Dynamic Chemical Equilibrium

Equilibrium Constant Expressions

Le Chatelier's Principle

Temperature Dependence of Equilibrium

Heterogeneous Equilibria

Reaction Quotient (Qc)

Gibbs Free Energy and Equilibrium

Equilibrium in Physical Processes

Applications of Equilibrium Constant

Acids and Bases: Arrhenius, Bronsted-Lowry and Lewis Concepts

Ionisation Constants of Weak Acids and Weak Bases

Ionisation of Water, Kw, pH and pOH

pKa, pKb and Strength of Acids/Bases

Buffer Solutions

Do you belong in the Top 10%?

Practice Test – MCQs, True/False

Multiple Choice Questions

Q1.In the reaction N2(g)+3H2(g)→2NH3(g)N_2(g) + 3H_2(g) \rightarrow 2NH_3(g)N2​(g)+3H2​(g)→2NH3​(g), which of the following changes will shift the equilibrium to the right?

Correct Answer: A

Q2.In the reaction N2(g)+3H2(g)→2NH3(g)N_2(g) + 3H_2(g) \rightarrow 2NH_3(g)N2​(g)+3H2​(g)→2NH3​(g), which condition will favor the formation of ammonia according to Le Chatelier's principle?

Correct Answer: C

Experience the StudyTunnel Method

Step 1: Practicing the Concepts

Step 2: Master Boss Exam

Step 3: Redemption Arena

True or False

Q1.According to the Bronsted-Lowry concept, an acid is a substance that donates a proton.

Correct Answer: True

Q2.In a closed system, the equilibrium constant KcK_cKc​ for a reaction is independent of the initial concentrations of the reactants and products.

Correct Answer: True

Q3.The equilibrium constant expression for the reaction N2(g)+3H2(g)→2NH3(g)N_2(g) + 3H_2(g) \rightarrow 2NH_3(g)N2​(g)+3H2​(g)→2NH3​(g) is given by Kc=[NH3]2[N2][H2]3K_c = \frac{[NH_3]^2}{[N_2][H_2]^3}Kc​=[N2​][H2​]3[NH3​]2​.

Correct Answer: True

Q3.Given the reaction HA⇌H++A−HA \rightleftharpoons H^+ + A^-HA⇌H++A− with an ionization constant Ka=1.8×10−5K_a = 1.8 \times 10^{-5}Ka​=1.8×10−5, calculate the pKapK_apKa​ of the acid.

Correct Answer: A

Unlock the Detailed Solution

Q4.Given the reaction NH3+H2O⇌NH4++OH−NH_3 + H_2O \rightleftharpoons NH_4^+ + OH^-NH3​+H2​O⇌NH4+​+OH−, if the pKbpK_bpKb​ of NH3NH_3NH3​ is 4.75, what can be inferred about the strength of NH3NH_3NH3​ as a base?

Correct Answer: B

Unlock the Detailed Solution

Q5.What is the relationship between Gibbs free energy change (ΔG\Delta GΔG) and the equilibrium constant (KKK) for a reaction at equilibrium?

Correct Answer: A

Unlock the Detailed Solution

Q6.In the equilibrium reaction CaCO3(s)⇌CaO(s)+CO2(g)CaCO_3(s) \rightleftharpoons CaO(s) + CO_2(g)CaCO3​(s)⇌CaO(s)+CO2​(g), what will be the effect on the equilibrium position if the pressure is increased by adding an inert gas at constant volume?

Correct Answer: C

Unlock the Detailed Solution

Q7.Which of the following statements is true regarding the Lewis concept of acids and bases?

Correct Answer: C

Unlock the Detailed Solution

Q8.In a closed system at equilibrium, what happens to the equilibrium position when the concentration of a reactant is increased?

Correct Answer: A

Unlock the Detailed Solution

Q9.For the reaction 2NO2(g)→N2O4(g)2NO_2(g) \rightarrow N_2O_4(g)2NO2​(g)→N2​O4​(g), which of the following changes will shift the equilibrium to the right?

Correct Answer: B

Unlock the Detailed Solution

Q10.Considering the reaction 2NO2(g)→N2O4(g)2NO_2(g) \rightarrow N_2O_4(g)2NO2​(g)→N2​O4​(g), which is exothermic, how will an increase in temperature affect the equilibrium constant KcK_cKc​?

Correct Answer: B

Unlock the Detailed Solution

Sign in to reveal the answer

Q4.According to Le Chatelier's principle, increasing the pressure on a gaseous reaction where the number of moles of gaseous reactants is greater than the number of moles of gaseous products will shift the equilibrium towards the products.

Correct Answer: True

Sign in to reveal the answer

Q5.The equilibrium constant KcK_cKc​ for an exothermic reaction decreases as the temperature increases.

Correct Answer: True

Sign in to reveal the answer

Q6.In a heterogeneous equilibrium involving the reaction CaCO3(s)→CaO(s)+CO2(g)CaCO_3(s) \rightarrow CaO(s) + CO_2(g)CaCO3​(s)→CaO(s)+CO2​(g), the equilibrium constant expression includes the concentration of CaCO3(s)CaCO_3(s)CaCO3​(s).

Correct Answer: False

Sign in to reveal the answer