Here’s a explanation of the relationship between enthalpy, entropy, and free energy:
1. Enthalpy (H)
- Measures the heat content of a system at constant pressure.
- Positive ΔH → heat is absorbed (endothermic).
- Negative ΔH → heat is released (exothermic).
2. Entropy (S)
- Measures the disorder or randomness of a system.
- Positive ΔS → system becomes more disordered.
- Negative ΔS → system becomes more ordered.
3. Free Energy (G, Gibbs Free Energy)
- Combines enthalpy and entropy to predict if a process is spontaneous at constant temperature and pressure.
- Spontaneous reactions: free energy decreases.
- Non-spontaneous reactions: free energy increases.
Relationship (Conceptual)
- Free energy depends on both heat and disorder:
- A process can be spontaneous if it releases heat (ΔH negative) or if entropy increases (ΔS positive), or both.
- If heat is absorbed but entropy increases enough, the reaction can still be spontaneous.
Simple Example:
- Ice melting at room temperature:
- ΔH > 0 (absorbs heat)
- ΔS > 0 (disorder increases)
- Free energy ΔG < 0 → the process happens spontaneously.
In short: Free energy = balance between enthalpy and entropy, and it tells whether a process will happen naturally.