Class 11 Chemistry - CBSE
Thermodynamics
The Thermodynamics chapter in Class 11 Chemistry explores energy changes accompanying physical and chemical processes. You will study key terms like system, surroundings, internal energy, enthalpy, entropy, and Gibbs free energy. Understanding the First Law of Thermodynamics helps calculate heat and work, while the Second and Third Laws explain spontaneity and disorder. This chapter is fundamental for understanding chemical equilibrium and electrochemistry. For CBSE board exams, it is a high-scoring, numerical-heavy chapter that consistently contributes significant weightage, making a clear grasp of thermodynamic sign conventions and enthalpy calculations essential for success.
Start Learning FreeKey Concepts
System and Surroundings
The part of the universe under thermodynamic study is the system, and everything else in the universe constitutes the surroundings.
First Law of Thermodynamics
Energy can neither be created nor destroyed, only converted from one form to another, expressed mathematically as delta U = q + w.
Enthalpy (H)
A state function representing heat content measured at constant pressure, where the change in enthalpy (delta H) determines whether a reaction is exothermic or endothermic.
Entropy (S)
A measure of the degree of randomness or disorder in a system, which increases in spontaneous processes according to the Second Law.
Gibbs Free Energy (G)
The thermodynamic potential that predicts the spontaneity of a reaction at constant temperature and pressure, where a negative delta G indicates spontaneity.
Important Formulas
Board Exam Info
In CBSE Class 11 Chemistry exams, Thermodynamics typically carries around 6 to 8 marks. Questions frequently include numerical problems on Hess's Law, calculating enthalpy changes, finding delta G to predict spontaneity, and conceptual reasons regarding entropy and state functions.
Frequently Asked Questions
What is the difference between state functions and path functions?
State functions (like pressure, volume, temperature, internal energy) depend only on the initial and final states of the system, whereas path functions (like work and heat) depend on the specific path taken during the change.
Why is delta H negative for exothermic reactions?
In exothermic reactions, the system releases heat to the surroundings, meaning the enthalpy of the products is lower than that of the reactants, resulting in a negative delta H.
How do we know if a reaction is spontaneous?
A reaction is spontaneous if the total entropy change (delta S total) is positive, or equivalently, if the Gibbs free energy change (delta G) is negative at constant temperature and pressure.
Learn Thermodynamics with Your AI Tutor
10 different ways to study this chapter. Free for 3 chapters per day.
Lecture
Key Points
Interactive
Quiz
Flashcards