What this Gibbs free energy calculator tells you
This Gibbs free energy calculator turns the values for this specific relationship into an answer with visible substitutions and units. Select ΔG, ΔH, ΔS, or temperature as the unknown, then enter the three visible known quantities for one consistent reaction basis.
The result answers only the selected Gibbs free energy question. It uses the model and assumptions stated on this page together with the values and choices shown in the form. Record any reference state or convention required by your course before comparing the answer with a textbook or data table.
Formula and unit check for Gibbs free energy
The page shows the working expression ΔG = ΔH − TΔS. ΔH and ΔG use kJ/mol, ΔS uses J/(mol·K), and TΔS is divided by 1,000 before it is combined with the energy terms.
Read the displayed substitution from left to right and confirm that each input appears once in the role named by the formula. If the units or sign do not lead to the requested quantity, correct the setup instead of trusting a plausible-looking decimal.
Work through a Gibbs free energy example
For a representative classroom example, with ΔH = −92.22 kJ/mol, ΔS = −199.65 J/(mol·K), and T = 298.15 K, the result is about −32.7 kJ/mol. The calculator keeps the substituted values visible so you can compare the sign, scale, and rounding with your own work. Try changing one input at a time: the direction of the change should agree with the formula, while the other assumptions remain fixed.
When a result surprises you, repeat the arithmetic with the displayed intermediate value, then reread the active fields described above. A different mode, sign, unit, or model assumption can change the conclusion even when the arithmetic itself is correct.
How to interpret the result
A negative calculated ΔG is favorable for the stated direction under the supplied conditions, but it does not establish reaction speed, yield, or safety.
Keep significant figures appropriate to the measurements and constants. Do not report ten meaningful digits just because the calculator can display them. For a formal assignment, cite the data source or convention required by the course. For a practical decision, confirm the result with a validated property table, instrument, or qualified professional.
Scope, limitations, and private use
Spontaneity is conditional on the supplied state, temperature, and standard-state basis; it is not a reaction-rate prediction. The page is intended for learning, checking homework, and routine estimates. It does not provide a safety limit, operating procedure, regulatory conclusion, or guarantee that a real sample follows an ideal model.
The values are calculated in the current browser tab. NexaCurrent does not upload the quantities, formulas, chemical names, element choices, or other information entered here, and no account is needed. Copying is a deliberate action after the answer and working are visible. Refreshing or leaving the page clears the current calculation, so keep a copied result if it is needed for later study.