# Entropy Formula

Entropy is simply a measure of the amount of molecular disorder within a system. A system that has all its atoms arranged in some perfectly ordered manner has an entropy value of zero. This is the substance of the third law of thermodynamics. Entropy is a measure of the amount of molecular disorder within a system. Entropy can only be produced within a system.

**The change in entropy is denoted by the formula,**

$\Delta$$S = S_{f} - S_{i}$.

**In thermodynamic definition, the expression for entropy is given below.**

dS = $\frac{dq_{rev}}{T}$

$\Delta$$S_{o}$ = $\Delta$$S_{products}$ - $\Delta$$S_{reactant}$

$\Delta$$S_{V}$ = $\frac{\Delta H_{V}}{T_{b}}$.