Second Law of Thermodynamics | complete notes| class 12|NEB|

It states that the total entropy of an isolated system always increases over time, or at best, remains constant in ideal situations. 

Heat flows from hot to cold: Another way of stating the Second Law is that heat will naturally flow from a hot object to a colder one.

Carnot cycle: The Carnot cycle is a theoretical cycle that describes the most efficient possible heat engine.  In this cycle, the maximum efficiency is achieved when the heat is transferred at a constant temperature.

Reversible and irreversible processes: A reversible process is one that can be undone without any net increase in entropy. 

Kelvin-Planck statement and Clausius statement: There are two statements of the Second Law of Thermodynamics: the Kelvin-Planck statement and the Clauses statement. The Kelvin-Planck statement states that no engine can operate in a cycle and produce a net amount of work while transferring heat from a single thermal reservoir. The Clausius statement states that heat cannot spontaneously flow from a cold object to a hot one.

Entropy change and Gibbs free energy: The entropy change of a system can be calculated using the change in Gibbs free energy. The Gibbs free energy is a measure of the energy available to do work in a system.