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Thermodynamics
Thermodynamics

Entropy Change

ΔS=QrevT\Delta S = \frac{Q_{rev}}{T}

Entropy change for reversible isothermal process.

Variables

ΔS
Entropy change
Change in entropy
J/K
Q_rev
Reversible heat
Heat in reversible process
J
T
Temperature
Absolute temperature
K

Derivation

dS = δQ_rev/T. For isothermal: ΔS = Q/T.

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Common questions

What is the Entropy Change formula?

Entropy Change is written ΔS = frac{Qᵣₑᵥ}{T}. Entropy change for reversible isothermal process. It belongs to Thermodynamics, under Second Law.

What are the units in ΔS = frac{Qᵣₑᵥ}{T}?

In SI units, ΔS is entropy change, measured in kg·m²/(s²·K); Q_rev is reversible heat, measured in kg·m²/s²; T is temperature, measured in K.

How is the Entropy Change formula derived?

dS = δQ_rev/T. For isothermal: ΔS = Q/T. The result is ΔS = frac{Qᵣₑᵥ}{T}.