免费吉布斯自由能计算器
计算吉布斯自由能变化，判断反应自发性。
Gibbs Free Energy (ΔG)
-85.10 kJ
Gibbs Free Energy (ΔG) vs Enthalpy Change (ΔH)
公式
## Gibbs Free Energy ### Formula **ΔG = ΔH − TΔS** Where: - **ΔG** = Gibbs free energy change (kJ) - **ΔH** = enthalpy change (kJ) - **T** = temperature (K) - **ΔS** = entropy change (J/K, converted to kJ/K by dividing by 1000) If ΔG < 0, the reaction is spontaneous. If ΔG > 0, it is non-spontaneous. If ΔG = 0, the system is at equilibrium.
计算示例
A reaction with ΔH = -100 kJ and ΔS = -50 J/K at 298 K.
- 01ΔG = ΔH - TΔS
- 02ΔG = -100 - (298 × (-50)/1000)
- 03ΔG = -100 - (-14.9)
- 04ΔG = -100 + 14.9
- 05ΔG = -85.1 kJ (spontaneous)
常见问题
What does ΔG tell you?
ΔG predicts spontaneity at constant temperature and pressure. Negative ΔG means the reaction can proceed spontaneously. It does not predict how fast the reaction occurs.
Can a reaction with positive ΔH be spontaneous?
Yes, if the entropy increase (TΔS) is large enough to make ΔG negative. Endothermic reactions can be spontaneous when entropy drives them.
What is the relationship between ΔG and K?
ΔG° = -RT ln(K). A large negative ΔG° corresponds to a large equilibrium constant, favoring products.
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