Gibbs Free Energy & Spontaneity Calculator

Determine whether a chemical reaction proceeds spontaneously utilizing standard enthalpy changes, entropy shifts, and temperature boundary parameters. Find dynamic equilibrium crossover thresholds instantly.

Gibbs Free Energy & Spontaneity Solver

Inputs

Enthalpy Change (ΔH)

kJ/mol

Entropy Change (ΔS)

J/(mol·K)

Temperature (T)

Gibbs Free Energy change (ΔG°)

-142.18 kJ/mol

Reaction Spontaneity State

Spontaneous (Exergonic)

The forward reaction proceeds naturally. Energy is released into the surroundings, and the system moves toward equilibrium without external work.

Thermodynamic Equation Verification Block

Base Equation: ΔG = ΔH − (T × ΔS)

ΔG = -198.20 kJ − (298.15 K × (-187.9 / 1000) kJ/K)

ΔG = -198.20 kJ − (298.15 K × -0.1879 kJ/K)

ΔG = -142.18 kJ/mol

Entropy Constraint Matrix Rule: Spontaneous ONLY at LOW temperatures

Equilibrium Threshold (ΔG = 0) at Temperature: 1054.82 K (781.67 °C)

Understanding Gibbs Free Energy (ΔG)

Gibbs Free Energy (G) is a thermodynamic potential that measures the maximum reversible work performable by a system at constant temperature and pressure. In chemical reactions, the net change in Gibbs Free Energy (\(\Delta G\)) functions as the ultimate metric determining reaction spontaneity.

The standard criterion relationship is defined mathematically by the Gibbs-Helmholtz function statement:

ΔG = ΔH − TΔS

Where individual variables track distinct thermal fields:

ΔH (Enthalpy Change): The heat energy exchanged during chemical bond reconfigurations at constant pressure (kJ/mol).
T (Absolute Temperature): The molecular kinetic energy state baseline, quantified strictly using the absolute Kelvin scale.
ΔS (Entropy Change): The system's dimensional degree of molecular disorder or energy dispersion, tabulated in J/(mol·K). *(Must be divided by 1,000 to balance kJ units).*

The Spontaneity Status Matrix Matrix

By evaluating the sign outcome profile of \(\Delta G\), thermodynamic behaviors fall into three clean categories:

ΔG < 0 (Spontaneous / Exergonic): The process drops down an energy gradient, releasing free energy available to do work. The reaction moves forward independently.
ΔG > 0 (Non-Spontaneous / Endergonic): The reaction requires a continuous input of external energy to force the forward transformation.
ΔG = 0 (Dynamic Chemical Equilibrium): The forward transformation rate perfectly equals the reverse path speed. Net composition remains constant.