🌡️ Thermodynamic Spontaneity & Equilibrium
Gibbs Free Energy Calculator ($\Delta G = \Delta H - T\Delta S$)
Compute change in Gibbs free energy ($\Delta G$), determine chemical reaction spontaneity (exergonic vs endergonic), equilibrium constant ($K_{\text{eq}}$), and crossover temperature ($T_{\text{eq}}$).
🏭 Haber Ammonia Synthesis
🧊 Ice Melting at 0°C
🔥 Glucose Combustion
🧱 Limestone Decomposition
Thermodynamic Parameters
kJ/mol
ΔH < 0 = Exothermic, ΔH > 0 = Endothermic
J / (mol·K)
ΔS > 0 = Increase in disorder / entropy
Change in Gibbs Free Energy (ΔG)
-32.96 kJ/mol
Equilibrium ($K_{\text{eq}}$)
5.98 × 10⁵
Entropy Term ($T\Delta S$)
-59.26 kJ/mol
Crossover Temp ($T_{\text{eq}}$)
464.0 K (190.9 °C)
💡 Thermodynamic Behavior:
Because $\Delta H < 0$ and $\Delta S < 0$, the reaction is spontaneous at lower temperatures ($T < 464.0\text{ K}$) and non-spontaneous at elevated temperatures.
The Second Law of Thermodynamics & Gibbs Energy
Gibbs free energy determines whether a reaction occurs without external work:
$$\Delta G = \Delta H - T \Delta S, \quad K_{\text{eq}} = e^{-\frac{\Delta G^\circ}{R T}}$$
| $\Delta H$ | $\Delta S$ | $\Delta G = \Delta H - T\Delta S$ | Spontaneity Condition |
|---|---|---|---|
| Negative ($-$) | Positive ($+$) | Always Negative ($-$) | Spontaneous at all temperatures |
| Positive ($+$) | Negative ($-$) | Always Positive ($+$) | Non-spontaneous at all temperatures |
| Negative ($-$) | Negative ($-$) | Negative at low $T$ | Spontaneous only at low temperatures ($T < \Delta H/\Delta S$) |
| Positive ($+$) | Positive ($+$) | Negative at high $T$ | Spontaneous only at high temperatures ($T > \Delta H/\Delta S$) |