Gibbs Free Energy Calculator
ΔG = ΔH − TΔS, with the unit mismatch handled.
Work out Gibbs Free Energy. ΔG = ΔH − TΔS, with the unit mismatch handled. Names the convention that makes the answer wrong.
ΔG (kJ/mol)
-159.63
Spontaneous at this temperature
ΔG = ΔH − TΔS, with enthalpy in kJ/mol and entropy in J/(mol·K) because that is how tables publish them — mixing the two by a factor of a thousand is the commonest error here, and the conversion is done for you above. With ΔH and ΔS opposed in sign, the outcome is the same at every temperature. Spontaneous means thermodynamically favoured, not fast — diamond turning to graphite has a negative ΔG and takes geological time.
How the Gibbs Free Energy Calculator works
Enthalpy is tabulated in kJ/mol and entropy in J/(mol·K), and mixing the two by a factor of a thousand is the commonest error in this calculation. The conversion happens here rather than being left to the reader.
Also known as: delta g calculator · spontaneity calculator · gibbs free energy formula · is a reaction spontaneous
Frequently asked questions
How do I calculate Gibbs free energy?
ΔG = ΔH − TΔS, with T in kelvin and the units reconciled — entropy is usually in J/(mol·K) while enthalpy is in kJ/mol.
What does a negative ΔG mean?
The reaction is thermodynamically favoured. It does not mean fast: diamond turning to graphite has a negative ΔG and takes geological time.
When does temperature decide the outcome?
When ΔH and ΔS share a sign. Then there is a crossover temperature where ΔG changes sign — which this page reports when one exists.
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