Entropy and Free Energy Table Builder

Build thermodynamic data tables for chemical reactions and processes. Compute standard entropy (ΔS°), Gibbs free energy (ΔG°), and reaction spontaneity from enthalpy (ΔH°) and temperature. Supports units: J, kJ, cal, kcal, eV; K, °C, °F. Fully offline, no data sent.

Educational only. Follow your lab SOPs and SDS.

Thermodynamic Table Input

Reaction / Process Name

Temperature (T)

Enthalpy Change (ΔH°)

Entropy Change (ΔS°)

Precision:

Why Thermodynamic Tables Matter

Building tables of entropy and free energy changes helps predict reaction feasibility, equilibrium positions, and energy requirements for industrial processes, biological pathways, and materials synthesis. This tool automates the calculations while keeping units consistent.

Step‑by‑Step Usage

Enter reaction name, temperature, enthalpy change (ΔH°), and entropy change (ΔS°). Use positive for endothermic/entropy‑increase, negative for exothermic/entropy‑decrease.
Select appropriate units for each field. The tool internally converts to J and K.
Click "Calculate ΔG & Build Row" to compute Gibbs free energy (ΔG° = ΔH° – TΔS°) and equilibrium constant (K = e^–ΔG°/RT).
The row is added to the table. You can build a multi‑reaction table for comparison.
Use "Copy Row" or "Export Table" for your lab notebook.

Realistic Examples

Example 1: Formation of water (liquid)

T = 298.15 K, ΔH° = –285.83 kJ/mol, ΔS° = –0.163 kJ/(mol·K) → ΔG° = –237.13 kJ/mol, K ≈ 3.5×10⁴¹ (highly favorable).

Example 2: Vaporization of water at 373 K

T = 373 K, ΔH° = +40.7 kJ/mol, ΔS° = +109 J/(mol·K) → ΔG° = 0 kJ/mol, K = 1 (at boiling point, equilibrium).

Reference Values & Common Pitfalls

Constant	Value	Unit
Gas constant (R)	8.314462618	J/(mol·K)
Faraday constant (F)	96485.33212	C/mol
Zero Celsius	273.15	K

Unit mismatch: Using ΔH in kJ and ΔS in J gives wrong ΔG by factor of 1000.
Temperature scale: ΔS° must be per Kelvin, not per °C.
Sign convention: Negative ΔG means spontaneous in forward direction under standard conditions.

Frequently Asked Questions

What are the assumptions of this calculator?

Assumes ideal behavior, constant ΔH° and ΔS° over the temperature range (no phase changes), and standard state (1 bar for gases, 1 M for solutions).

When do these approximations fail?

At extreme pressures, for real gases, during phase transitions, or when heat capacity changes significantly with temperature.

How should I measure ΔH and ΔS experimentally?

Use calorimetry for ΔH, and measure heat capacities or equilibrium constants at different temperatures for ΔS. Always calibrate instruments and use pure substances.

Any safety considerations?

Thermodynamic data alone does not indicate reaction kinetics or hazards. Highly exothermic reactions (large negative ΔH) may be energetic. Always consult SDS before mixing chemicals.

Menu

Entropy and Free Energy Table Builder

AI Assistant

Was this tool helpful?