Calculator Servicescalculatorservices.com
Chemistry

Gibbs Free Energy

ΔG = ΔH − TΔS. Free online Gibbs Free Energy. Calculate gibbs free energy online — fast, accurate, mobile-friendly, no signup needed.

ΔG (kJ/mol)
-79.8

Derivation

  1. ├── 01GivenH = -50, T = 298, S = 100
  2. ├── 02Formulae.H-e.T × e.S / 1e3
  3. ├── 03Substitutee.-50-e.298 × e.100 / 1e3
  4. └── 04Compute ΔG (kJ/mol)-79.8
Did you know?

The phrase "kinetic energy" was coined by William Thomson (Lord Kelvin) and Peter Guthrie Tait in 1867 — before that physicists called it vis viva, "living force".

§01What is

Understanding the Gibbs Free Energy

The Gibbs Free Energy computes ΔG (kJ/mol) from 3 inputs: δh (kj/mol), t (k), δs (j/mol·k). ΔG = ΔH − TΔS.

Chemistry turns grams and moles into reactions. Getting the stoichiometry, dilutions, or concentrations right is the difference between a lab result you can trust and one you can’t reproduce. The Gibbs Free Energy sits in that toolkit — it ΔG = ΔH − TΔS. Enter your numbers above and the result updates instantly; every step of the math is shown in the Derivation panel so you can see exactly how the answer was reached.

§02The Formula

How it’s calculated

e.H-e.T × e.S / 1e3

Where

H
ΔH (kJ/mol)
T
T (K)
S
ΔS (J/mol·K)
§03Practical Example

Step-by-step walkthrough

Scenario

Apply the formula to a realistic set of inputs: ΔH (kJ/mol) = -50, T (K) = 298, ΔS (J/mol·K) = 100.

  1. 01Start by noting the input — ΔH (kJ/mol): -50.
  2. 02Start by noting the input — T (K): 298.
  3. 03Start by noting the input — ΔS (J/mol·K): 100.
  4. 04Substitute these values into the formula: e.H-e.T × e.S / 1e3
  5. 05Compute ΔG (kJ/mol): the calculator returns -79.8.
  6. 06Cross-check the answer by opening the Derivation panel above — every line of math is shown so you can follow the computation end-to-end.
§04Variants

Common Gibbs Free Energy Problems

The formula gets rearranged depending on which variable you need. Here are the patterns you’ll run into in the real world — find the one that matches your problem and follow the worked steps.

01 · PATTERN

ΔH (kJ/mol) halved

H = -25 (from -50)

Keep every other input at its default and halve the δh (kj/mol). See how δg (kj/mol) responds.

  1. 01New ΔH (kJ/mol): -25
  2. 02Baseline ΔG (kJ/mol): -79.8
  3. 03New ΔG (kJ/mol): -54.8
  4. 04ΔG (kJ/mol) increases by 31.3% → use this sensitivity to plan for real-world variation.
02 · PATTERN

ΔH (kJ/mol) doubled

H = -100 (from -50)

Keep every other input at its default and double the δh (kj/mol). See how δg (kj/mol) responds.

  1. 01New ΔH (kJ/mol): -100
  2. 02Baseline ΔG (kJ/mol): -79.8
  3. 03New ΔG (kJ/mol): -129.8
  4. 04ΔG (kJ/mol) decreases by 62.7% → use this sensitivity to plan for real-world variation.
03 · PATTERN

T (K) halved

T = 149 (from 298)

Keep every other input at its default and halve the t (k). See how δg (kj/mol) responds.

  1. 01New T (K): 149
  2. 02Baseline ΔG (kJ/mol): -79.8
  3. 03New ΔG (kJ/mol): -64.9
  4. 04ΔG (kJ/mol) increases by 18.7% → use this sensitivity to plan for real-world variation.
04 · PATTERN

T (K) doubled

T = 596 (from 298)

Keep every other input at its default and double the t (k). See how δg (kj/mol) responds.

  1. 01New T (K): 596
  2. 02Baseline ΔG (kJ/mol): -79.8
  3. 03New ΔG (kJ/mol): -109.6
  4. 04ΔG (kJ/mol) decreases by 37.3% → use this sensitivity to plan for real-world variation.
§05FAQ

Frequently asked questions

Yes. The calculator implements the standard formula as documented and returns exact floating-point results. No approximations are used unless noted in the formula.
Your feedback

How useful was this calculator?

Your ratings stay in your browser — they help us learn which tools people actually rely on.

Rate it
Was this helpful?