🌡️Enthalpy vs Entropy🌀
Enthalpy and entropy together decide whether a reaction is spontaneous. Gibbs free energy combines both into one prediction.
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🌡️Enthalpy
- ✓Measures total heat content (H)
- ✓Change ΔH shows heat absorbed or released
- ✓Negative ΔH favors spontaneity
- ✓Measured in joules or kJ/mol
- ✓Drives exothermic reactions
🌀Entropy
- ✓Measures disorder or randomness (S)
- ✓Change ΔS shows increase or decrease in disorder
- ✓Positive ΔS favors spontaneity
- ✓Measured in J/(mol·K)
- ✓Tends to increase in the universe
Verdict
Enthalpy tracks heat while entropy tracks disorder. Neither alone predicts spontaneity; Gibbs free energy, ΔG = ΔH − TΔS, combines them for the final verdict.
Frequently asked
Which one predicts spontaneity?+
Neither alone. Gibbs free energy combines enthalpy and entropy: a negative ΔG means spontaneous.
Does entropy always increase?+
The total entropy of the universe increases, though a local system can decrease in entropy.
What units does each use?+
Enthalpy uses kJ/mol; entropy uses J/(mol·K) because it includes temperature.
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