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Hannah's Energetics Emporium
Entropy? Enthalpy? more like gibberish!?!! Don't worry you have come to the right place!
Spontaneity
Definition
If a reaction is referred to as being "spontaneous", it causes a system to move from a less stable to a more stable state. It is the opposite of Enthalpy.
It depends on both the enthalpy change and the entropy change.
Both the enthalpy change and the entropy change can be combined and are expressed as Gibb's Free Energy change.
What does it depend on?
ALWAYS REMEMBER PRODUCTS - REACANTS!
Gibb's Free Energy
Gibb's Free Energy is represented by Delta G, it also is known as the 'free energy change'.
Gibb's Free Energy: Formula
∆G = ∆H - T∆S
If a reaction is spontaneous it does not always ensure that it will proceed without the addition of any energy.
For example; the combustion of coal is spontanoeus despite this coal is stable in the air. Coal will only burn on its own accord subsequent to recieving some initial energy in order for some of the molecules to have teh required activation energy for the reaction to proceed.
REMEMBER...
What makes it spontaneous?
For it to be spotaneous. the ∆G value MUST be nagative;
∆G <0 spontaneous
∆G > 0 NOT spontaneous
* where all values are measured under stanard conditions.
