Gibbs Free Energy Calculator

Calculate ΔG = ΔH − TΔS to determine reaction spontaneity and equilibrium.

⚡ Gibbs Free Energy – ΔG = ΔH − TΔS

ΔH – Enthalpy Change kJ/mol

T – Temperature K

ΔS – Entropy Change J/(mol·K)

ΔG – Gibbs Free Energy kJ/mol

⚠ Enter three known values.

Gibbs Equation

ΔG = ΔH − T·ΔS

ΔG

—

kJ/mol

⚡ Gibbs Free Energy Explained

ΔG = ΔH − TΔS

ΔG < 0 → Spontaneous ✓

ΔG > 0 → Non-spontaneous ✗

ΔG = 0 → Equilibrium ⚖️

ΔG° = −RT ln(K)

Note: ΔS is in J/(mol·K), so convert by dividing by 1000 when using kJ/mol units for ΔH.

📖 Example

✅ Water Formation: 2H₂ + O₂ → 2H₂O

ΔH = −286 kJ/mol, ΔS = −163 J/(mol·K), T = 298 K

TΔS = 298 × (−163/1000) = −48.57 kJ/mol

ΔG = −286 − (−48.57) = −237.4 kJ/mol

ΔG < 0 → Reaction is spontaneous!

❓ FAQ

What does negative ΔG mean?

ΔG < 0 means the reaction releases free energy and is thermodynamically favorable (spontaneous). It will proceed without external energy input.

What's the relationship between ΔG and K?

ΔG° = −RT ln(K), where K is the equilibrium constant, R = 8.314 J/(mol·K). If ΔG° < 0, K > 1 (products favored).

🔗 Related

Comprehensive Guide

Understanding Gibbs Free Energy: A Complete Guide

The Gibbs Free Energy Calculator is an essential analytical tool for chemistry students, educators, and laboratory professionals. Accurate Gibbs Free Energy calculations form the backbone of both theoretical studies and physical experiments. Mastering the concepts behind Gibbs Free Energy is crucial for understanding advanced chemical reactions and laboratory procedures.

Why is Gibbs Free Energy Important?

In analytical chemistry, precision is everything. Having a reliable way to compute Gibbs Free Energy saves time, prevents wasted materials, and ensures scientific accuracy.

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Speed

Instant

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Accuracy

100%

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Level

All Levels

Always verify your input units before calculating. Mismatched units (e.g., using mL instead of L) are the most common source of error when determining Gibbs Free Energy!

Common Applications

Academic Study: Verifying manual homework calculations.
Laboratory Practice: Standardizing lab reagent preparations.
Data Validation: Cross-checking experimental data analysis.

Relying solely on the calculator without understanding the underlying formula. Always review the step-by-step breakdown to internalize the mechanics.