| Enthalpy | Entropy | Gibbs Free Energy |
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| Enthalpy is the amount of heat energy transferred (heat absorbed or emitted) in a chemical process under constant pressure. | Entropy measures the amount of heat dispersed or transferred during a chemical process. | Gibbs Energy is also known as energy available to initiate a chemical process under constant pressure and temperature. |
| It is expressed as a change in enthalpy (ΔH) because the total enthalpy (H) of a system cannot be measured directly. | Nature tends to form chaos than order — aging, decaying, rusting, etc. Usable energy is transformed to unusable energy when work is performed. Entropy is often described as a measure of randomness but this mustn’t be confused with random patterns or arrangements.Entropy is about heat. The change in entropy is expressed as ∆S. The higher energy dispersal means higher entropy. | Some reactions are spontaneous (eg. rusting). A spontaneous process happens by itself without any energy added to the system (apart from the activation energy). A non-spontaneous process will not take place unless it is driven by an external source of energy.
∆G = ∆H — T•∆S∆G = Gibbs Free Energy ∆H = Change in Enthalpy T = Temperature in K ∆S = Change in Entropy |
| ΔH < 0 | ∆S > 0 | ∆G < 0 |
| • Total energy of products lower than total energy of reactants.
• The process is exothermic. • Gives off heat. |
Entropy increases. | Process is spontaneous |
The relation [dS <0] looks like a typo. I think it should be [dG <0], neatly fitting beneath the explanation for Gibbs' Energy :).
Thank you!!
I believe there is a typo……
In an exothermic reaction Total energy of products is lower than total energy of reactants..the natural flow is energy minimisation…..hence the delta is negative
With Positive change in H the process is endothermic…absorbs (latent) heat…..
Thank you so much for letting me know!