What is Gibbs Free Energy?

Gibbs Free Energy (G) is a thermodynamic potential that measures the maximum reversible work that can be performed by a thermodynamic system at constant temperature and pressure. In the context of chemistry, the change in Gibbs Free Energy (ΔG) is the most critical factor for determining whether a chemical reaction will occur spontaneously.

The standard equation for calculating this change is ΔG = ΔH - TΔS, where ΔH represents the change in enthalpy, T is the absolute temperature in Kelvin, and ΔS is the change in entropy. By using this Gibbs Free Energy Calculator, students and scientists can predict reaction behavior without manual unit conversion errors.

How to Interpret the Results

Once you calculate ΔG, the value tells you a specific story about the chemical process:

• ΔG < 0 (Negative): The reaction is spontaneous (exergonic). It can proceed in the forward direction without external energy.
• ΔG > 0 (Positive): The reaction is non-spontaneous (endergonic). Energy must be added to the system for the reaction to occur.
• ΔG = 0: The system is at equilibrium. There is no net change in the concentrations of reactants and products.

Step-by-Step Calculation Guide

To use this tool effectively, follow these simple steps:

1. Enter the Enthalpy Change (ΔH). Be mindful of whether the reaction is exothermic (negative) or endothermic (positive).
2. Enter the Entropy Change (ΔS). Note that entropy is often given in Joules (J), while enthalpy is in kiloJoules (kJ). Our calculator handles this conversion automatically.
3. Input the Temperature. Ensure you specify if your input is in Kelvin or Celsius.
4. Click Calculate to see the Gibbs Free Energy and the spontaneity status.