Understanding Entropy in Closed Systems

Entropy

A measure of disorder in a system.

Extensive Property

Property dependent on system size, like entropy (S).

Specific Entropy

Entropy per unit mass, denoted as s.

Mole Specific Entropy

Entropy per mole, denoted as s̅.

Reversible Process

A process that can be reversed without changes.

Irreversible Process

A process that cannot be reversed without changes.

Cycle Integral

Integral of heat transfer over a cycle.

T-s Diagram

Graphical representation of temperature vs. entropy.

h-s Diagram

Mollier diagram showing enthalpy vs. entropy.

Change in Entropy

Difference in entropy between two states.

Units of Entropy

Measured in J/K or kJ/K.

Reference State

Arbitrary state for calculating entropy values.

Third Law of Thermodynamics

Entropy approaches zero at absolute zero temperature.

Compressed Liquid

Liquid with entropy less than saturated liquid entropy.

Ideal Gas

Hypothetical gas following ideal gas laws.

Calorically Perfect Gas

Gas with constant specific heats and properties.

Isentropic Process

Reversible and adiabatic process with constant entropy.

Heat Transfer (Q)

Energy transferred due to temperature difference.

Absolute Temperature (T)

Temperature measured from absolute zero.

Integration of Entropy Change

Calculating change in entropy through integration.

Entropy Change for Incompressible Substances

Entropy change calculated using constant specific heat.

s_f and s_g

Saturated liquid and vapor entropy, respectively.

s_f < s < s_g

Condition for a mixture of liquid and vapor.

Negligible K.E. and P.E.

Assumption for simple compressible systems.