Bihar Board - Class 11 - Chemistry - Chapter 6: Thermodynamics Handwritten Notes

The "Thermodynamics" chapter deals with the study of energy, its transformations, and its relation to matter. It explains the fundamental principles of thermodynamics that govern the physical and chemical processes, including heat, work, and energy changes. This chapter is crucial for understanding the energy exchanges that occur during chemical reactions and physical transformations.

Key Points:

1. Definition of Thermodynamics:

   • Thermodynamics is the branch of science that deals with the relationships between heat, work, energy, and the transformations of energy in various systems.

2. Laws of Thermodynamics:

   • Zeroth Law: If two systems are each in thermal equilibrium with a third system, they are in thermal equilibrium with each other.
   • First Law (Law of Energy Conservation): Energy cannot be created or destroyed; it can only change from one form to another. Mathematically, $$ΔU=Q−W\Delta U = Q - W, where $$ΔU\Delta U is the change in internal energy, $$QQ is the heat added to the system, and $$WW is the work done by the system.
   • Second Law: The entropy of an isolated system always increases over time. It states that natural processes tend to move towards a state of greater disorder or randomness.
   • Third Law: As the temperature of a system approaches absolute zero, the entropy of the system approaches a minimum value.

3. Work and Heat:

   • Work is done when a force is applied to move an object, and energy is transferred in the process.
   • Heat refers to the transfer of energy due to temperature difference.

4. Internal Energy and Enthalpy:

   • Internal Energy (U): The total energy contained within a system, including both kinetic and potential energy of molecules.
   • Enthalpy (H): The heat content of a system at constant pressure. It is given by $$H=U+PVH = U + PV, where $$PP is pressure and $$VV is volume.

5. Entropy:

   • Entropy is a measure of disorder or randomness in a system. Higher entropy means greater disorder and lower energy availability for work.

6. Gibbs Free Energy:

   • Gibbs Free Energy (G): The energy available to do work at constant temperature and pressure. It is given by $$G=H−TSG = H - TS, where $$TT is the temperature and $$SS is the entropy.
   • If $$ΔG\Delta G is negative, the process is spontaneous; if positive, it is non-spontaneous.

7. Spontaneous and Non-Spontaneous Processes:

   • A process is considered spontaneous if it occurs naturally without external influence, and its spontaneity can be predicted using Gibbs free energy.

8. Thermodynamic Equilibrium:

   • A system is in thermodynamic equilibrium when its macroscopic properties do not change with time, and there is no net flow of energy.

9. Heat Engines and Refrigerators:

   • A heat engine is a device that converts heat energy into mechanical work.
   • A refrigerator is a device that transfers heat from a cooler to a warmer place, requiring external work to function.

Conclusion:

The "Thermodynamics" chapter provides essential knowledge of how energy is transferred and transformed in physical and chemical processes. By understanding the laws of thermodynamics, students gain insight into the principles that govern energy flow and the spontaneity of reactions. This chapter is fundamental for comprehending a wide range of processes in chemistry, physics, and engineering. Mastery of thermodynamics helps in understanding not only natural phenomena but also the practical applications like engines, refrigerators, and chemical reactions.

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