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7 L'entropie

What are the units of entropy?
First the units of entropy are Joules per Kelvin but the degree of disorder has no units. Secondly, the equation ( ii) defining entropy change does not recognise that the system has to be at equilibrium for it to be valid.
Why is the entropy of a substance not available?
This action is not available. Because the entropy of a substance depends on the amount of substance, the pressure, and the temperature, it is convenient to describe the entropy of a substance in terms of Sm °, its standard molar entropy, i.e., as the entropy of 1 mol of substance at the standard pressure of 1 atm (101.3 kPa) and given temperature.
What is entropy change in a reversible process?
The entropy change of the system (not including the surroundings) is well-defined as heat transferred to the system divided by the system temperature , . A reversible process is a quasistatic one that deviates only infinitesimally from thermodynamic equilibrium and avoids friction or other dissipation.
What are the Three Laws of entropy?
The first law deals with the conservation of energy, the second law is concerned with the direction in which spontaneous reactions go, and the third law establishes that at absolute zero, all pure substances have the same entropy, which is taken, by convention, to be zero.

What are the units of entropy?