Gibbs-Helmholtz Equation
Formula: G = H - T∆S
The Gibbs-Helmholtz Equation is an important thermodynamic equation that relates the Gibbs free energy change (G) for a process to its enthalpy change (H) and the entropy change (∆S) at a constant temperature (T). This equation is given by G = H - T∆S, where G is the Gibbs free energy, H is the enthalpy, T is the absolute temperature in Kelvin, and ∆S is the change in entropy. However, since ∆S can sometimes be hard to measure directly, it's often more practical to measure ∆G directly and calculate ∆S using ∆G = -T∆S. Hence, the formula is rearranged to G = H - T(∆G/T), which simplifies to G = H - T∆G.
In practical terms, this equation is used to predict the spontaneity of a reaction at a given temperature. If G is negative, the reaction is spontaneous; if it is positive, the reaction is non-spontaneous. This is a crucial concept in fields such as physical chemistry, chemical engineering, and materials science where predicting reaction tendencies is necessary.
Tags: Chemistry, Thermodynamics, Gibbs Free Energy, Enthalpy, Entropy