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NCERT Solutions for Class 11 Chemistry Chapter 5 Thermodynamics - PDF Download

JEE Mains & Advanced

NCERT Solutions class 11 chemistry - chapter 5 deals with the topic of thermodynamics in class 12 chemistry. This chapter provides an in-depth overview of the topic and responds to all the questions posed during the exercise. To ensure that students acquire a thorough understanding of the topics related to thermodynamics, it is suggested that they access NCERT Solutions class 12 chemistry - chapter 5. These solutions are written in plain language to be easier to understand. These class 11 chemistry solutions of chapter 5  are prepared by the chemistry teachers of eSaral.

Once you’ve completed this chapter, thermodynamics, you’ll be able to:

  • Provide an explanation of the terms system and surrounding

  • Distinguish between close, open and isolated systems

  • Explain internal energy, work and heat

  • States thermodynamics’s first law and expresses it mathematically

  • Calculate energy changes as work and heat contributions in chemical systems

  • Explain state functions (U, H), compares U and H

  • Measure experimentally U and H; defines standard states for H

  • Calculate enthalpy changes in various types of reactions

  • Distinguish between extensive and intensive properties

  • Define spontaneous and non-spontaneous processes

  • Explain entropy as a thermodynamic state function and applies it for spontaneous processes

  • Explain Gibbs energy (∆G) and establish a relationship between Gibbs energy (∆G) and the equilibrium constant.

Sections Covered in Chapter 5 - Thermodynamics

Section Name

Topic Name




Thermodynamics terms




Measurement of ΔU and ΔH: calorimetry


Enthalpy change, ΔH of a reaction-reaction enthalpy


Enthalpies for different types of reactions




Gibbs energy change and equilibrium

5.1 Thermodynamics terms: Thermodynamics refers to the study of how energy behaves in systems and how it changes over time. It includes a broad range of terms and concepts that describe how energy behaves, how heat behaves, how work behaves, and how different properties of matter interact with each other.

Here are some key terms and subtopics will be discussed in this section:

 5.1.1 the system and the surroundings

 5.1.2 types of the system

 5.1.3 the state of the system

 5.1.4 the internal energy as a state function 

5.2 Applications: As a fundamental science, thermodynamics has many practical applications in many different areas. Here are some of the most important applications of thermodynamics which are mentioned in the following subtopics.

      5.2.1 Work

      5.2.2 Enthalpy, ΔH

5.3 Measurement of ΔU and ΔH: calorimetry: Calorimetry uses a calorimeter to measure how much heat is being transferred between a system and the environment. It's used to measure changes in internal temperature (ΔU), as well as enthalpy (ΔH), which is how much energy is being transferred from one system to another.
Following subtopics will be discussed in this section:

  • ΔU measurements

  • ΔH measurements

5.4 Enthalpy change, ΔH of a reaction-reaction enthalpy: Enthalpy change is the amount of heat energy that's transferred during a chemical reaction at a constant pressure. It's the difference between the products' enthalpy and the reactants' enthalpy. It's often used to measure how much heat is released or absorbed during a reaction, and it can give us insight into the energy changes that happen during chemical processes.

Following subtopics will be discussed in this section:

  • Standard enthalpy of reactions

  • Enthalpy change during phase transformations

  • Standard enthalpy of formation

  • Thermochemical equations

  • Hess’s law of constant heat summation

5.5 Enthalpies for different types of reactions: Different types of reactions have enthalpies that give us an idea of the energy changes that happen in different chemical reactions.

Following subtopics will be discussed in this section:

  • Standard enthalpy of combustion

  • Enthalpy of atomization

  • Bond enthalpy

  • Lattice enthalpy

  • Enthalpy of solution

  • Enthalpy of dilution

5.6 Spontaneity: Spontaneity is a concept in thermodynamics that refers to the ability of a process to self-organize without the need for external intervention. It is a fundamental concept that describes the direction that a process will take under certain conditions. Spontaneity is closely related to the second law, which addresses the general behavior of energy and entanglement in a system.

Following subtopics will be discussed in this section:

  • Is decrease in enthalpy a criterion for spontaneity?

  • Entropy and spontaneity

  • Gibbs energy and spontaneity

  • Entropy and second law of thermodynamics

  • Absolute entropy and third law of thermodynamics

5.7 Gibbs energy change and equilibrium: Gibbs free energy change ( ΔG) is a fundamental principle of thermodynamics that describes whether a chemical reaction occurs spontaneously and in what direction. It is especially important for reactions at constant temperatures and pressures. ΔG evaluates both the enthalpy and the entropy of a system to determine thermodynamic feasibility and the direction of a reaction.

Key Points of Class 11 Chemistry NCERT Solutions Chapter 5 Thermodynamics

  • Thermodynamics is concerned with the effects of energy changes on chemical or physical systems and allows for the quantification of these changes and the development of predictions. For this purpose, the universe is divided into a system and the surroundings.

  • Energy is converted into heat if the system and environment are at different temperature levels.

  • Intrinsic properties are those whose value is not dependent on the quantity of the substance in the system. For example, temperature, pressure and viscosity are intensive properties, while surface tension and dielectric properties are extensive properties. For example, mass, volume and surface area are extensive properties, while enthalpy and entropy are intensive properties. Free energy and heat capacity are also extensive properties.

  • The first law of thermodynamics states that the amount of energy in the universe is always the same during changes in chemical and physical conditions. Enthalpy (H) is the sum of the internal energy and the pressure-volume energy of a system at a certain temperature and pressure, also known as heat content. Enthalpy change (ΔH) is the amount of heat change that occurs during the process at a given temperature and pressure. Enthalpy of reactions ( ΔrHθ) is the enthalpy change that occurs during a chemical reaction when a balanced chemical equation predicts the products of the reaction.

  • Hess's law states that the enthalpy changes in a given reaction are the same whether it is a single step reaction or a series of steps. 

  • The bond enthalpy is the average energy needed to break a mole of a specific bond type in a gas molecule.

Benefits of Downloading the PDF of NCERT Solutions Class 11 Chemistry Chapter 5 Thermodynamics

  • Students studying this subject can benefit from the convenience of downloading the PDF of the NCERT Solutions for Chapter 5 of Class 11 Chemistry, "Thermodynamics". 

  • NCERT solutions offer a range of benefits to help students gain a better understanding of thermodynamics, such as clarity of concepts, insights, and explanations beyond what is provided in the textbook. 

  • NCERT solutions provide practice and revision options to ensure that students have a thorough grasp of the material, allowing for regular practice and revision. 

  • Furthermore, NCERT solutions can help students prepare for exams by allowing them to work through various types of questions that may be included in the exam. 

  • NCERT solutions can save time by providing clear explanations, allowing students to move forward without being bogged down in a problem. Finally, once the PDF is downloaded, students can access the solution offline, allowing them to study without the need for an internet connection.

Frequently Asked Questions

Question 1: What is thermodynamics?

Answer 1: Thermodynamics is a field of study that focuses on energy transformations and relationships between different types of energy. It includes concepts such as heat, work and properties of matter associated with temperature and pressure.

Question 2: What are the laws of thermodynamics?

Answer 2: The Four Laws of Thermodynamics are the fundamental laws that govern energy and its transformation. They are Zeroth Law, First Law, Second Law, and Third Law. The Zeroth Law describes temperature equilibrium, the First Law describes conservation of energy, the Second Law describes entropy and directionality, and the Third Law describes approaching absolute zero.



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