Free Gibbs Free Energy Calculator
Use this Free Gibbs Free Energy Calculator to work through the same calculation as the main calculator page with clear steps, examples, and result context.
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What This Free Gibbs Free Energy Calculator Helps You Do
This page keeps the two most practical Gibbs-energy workflows together: calculate Delta G from enthalpy and entropy, or convert standard Gibbs energy into an equilibrium constant. That covers most spontaneous/non-spontaneous and equilibrium questions without extra algebra.
The interpretation text spells out spontaneity directly so the sign of Delta G becomes immediately useful.
How to Calculate Free Gibbs Free Energy Calculator
- Choose the Gibbs workflow: Use thermodynamic mode to compute Delta G from Delta H, Delta S, and temperature, or switch to equilibrium mode to estimate K from Delta G°.
- Enter temperature and energy values: The calculator converts entropy to the same energy basis as enthalpy before evaluating the equation.
- Evaluate spontaneity or equilibrium tendency: Negative Delta G indicates spontaneity under the stated conditions, while the size of K indicates which side is favored at equilibrium.
- Use the result in context: A process can switch from spontaneous to non-spontaneous if temperature changes the TDelta S term enough.
Free Gibbs Free Energy Calculator Formula
| Variable | Meaning | Unit |
|---|---|---|
| Delta G | Gibbs free energy change | kJ/mol |
| Delta H | Enthalpy change | kJ/mol |
| Delta S | Entropy change | J/mol·K |
| T | Absolute temperature | K |
| K | Equilibrium constant | dimensionless |
Use the worked examples below to check how the formula behaves with real values. If the result looks unexpected, verify the unit assumptions and the meaning of each variable before interpreting the answer.
Worked Examples
- Delta H: -92 kJ/mol
- Delta S: -198 J/mol·K
- T: 298 K
Result: Delta G is about -33.0 kJ/mol.
The reaction remains spontaneous because the enthalpy term outweighs the unfavorable entropy contribution.
- Delta H: 20 kJ/mol
- Delta S: 120 J/mol·K
- T: 350 K
Result: Delta G is -22.0 kJ/mol.
A positive entropy term can make a process spontaneous at sufficiently high temperature.
- Delta G°: -10 kJ/mol
- T: 298 K
Result: K is about 56.6.
The equilibrium favors products because the standard Gibbs energy is negative.
- Delta G°: 0 kJ/mol
- T: 298 K
Result: K is 1.
A zero standard Gibbs energy corresponds to an equilibrium constant of 1 under the chosen standard-state framework.
How to Interpret Your Results
| Range | Meaning | Action |
|---|---|---|
| Delta G below 0 | Spontaneous under the stated conditions. | The process is thermodynamically favored in the forward direction. |
| Delta G near 0 | Near equilibrium. | Small changes in conditions can shift the direction of preference. |
| Delta G above 0 | Non-spontaneous in the forward direction. | External work or different conditions would be needed to favor the forward process. |
Frequently Asked Questions
References
Last reviewed: March 2026