Class 11 Chemistry - BIHAR
Thermodynamics
The chapter Thermodynamics in Class 11 Chemistry introduces you to the study of energy changes accompanying physical and chemical processes. It is a crucial physical chemistry chapter for Bihar Board (BSEB) students as it lays the foundation for understanding chemical equilibrium and spontaneity. You will learn about system and surroundings, the First Law of Thermodynamics regarding energy conservation, enthalpy changes in reactions, entropy as a measure of randomness, and Gibbs free energy which determines whether a reaction will happen spontaneously. Scoring well in numerical problems from this chapter will significantly boost your overall chemistry board exam percentage.
Start Learning FreeKey Concepts
System and Surroundings
A system is the specific part of the universe under thermodynamic study, while everything else outside the system constitutes the surroundings.
First Law of Thermodynamics
Energy can neither be created nor destroyed, only transformed from one form to another, expressed mathematically as delta U = q + w.
Enthalpy (H)
Enthalpy is the total heat content of a system at constant pressure, where the change in enthalpy (delta H) determines if a reaction is exothermic or endothermic.
Entropy (S)
Entropy is a measure of the degree of randomness or disorder of a system, which increases during spontaneous processes in an isolated system.
Gibbs Free Energy (G)
Gibbs free energy is the thermodynamic potential that measures the maximum reversible work obtainable from a system, and its sign (delta G) dictates reaction spontaneity.
Important Formulas
Board Exam Info
In the Bihar Board (BSEB) Class 11 Chemistry exams, Thermodynamics is a high-weightage chapter typically carrying around 6 to 8 marks. Questions frequently include numerical problems on enthalpy of reactions (Hess's Law), calculating work done, predicting the sign of entropy and Gibbs free energy, and deriving thermodynamic relationships.
Frequently Asked Questions
What is the difference between state functions and path functions?
A state function depends only on the initial and final states of the system (like pressure, volume, temperature, internal energy), whereas a path function depends on the path taken to reach that state (like heat and work).
How do we know if a reaction is spontaneous using Gibbs free energy?
A reaction is spontaneous if delta G is negative. If delta G is positive, the reaction is non-spontaneous, and if delta G is zero, the system is at equilibrium.
Why is delta n_g important in the enthalpy formula?
Delta n_g represents the change in the number of moles of gaseous products and reactants, which is necessary to convert between internal energy change (delta U) and enthalpy change (delta H) for gas-phase reactions.
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