# Entropy

- Entropy Change (ΔS) - The change in entropy (ΔS) is determined by subtracting the initial entropy from the final entropy of a thermodynamic system. It measures the disorder or number of configurations within the system.
- Gibbs-Helmholtz Equation - The Gibbs-Helmholtz Equation relates the Gibbs free energy change to the enthalpy and entropy changes of a reaction at a constant temperature. Learn how to use this equation.
- Shannon's Information Entropy - Shannon's information entropy quantifies the uncertainty of a random variable by measuring the average rate at which information is produced by a stochastic source of data.