Spontaneity & exo/endothermic
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Re: Spontaneity & exo/endothermic
No they are not all spontaneous. This is because there could be a high activation energy required to start the reaction.
A logical example is burning wood or paper. It is an exothermic reaction because it releases heat; however, not all paper or wood spontaneously burns due to the activation energy required to start the reaction.
A logical example is burning wood or paper. It is an exothermic reaction because it releases heat; however, not all paper or wood spontaneously burns due to the activation energy required to start the reaction.
Re: Spontaneity & exo/endothermic
Not all exothermic reactions are spontaneous. A negative Delta G means that a reaction is spontaneous. The change in enthalpy can contribute to this but an exothermic reaction is not the only factor deciding if a reaction is spontaneous.
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Re: Spontaneity & exo/endothermic
The Gibbs free energy of the reaction determines if it is spontaneous by calculation of a negative value.
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Re: Spontaneity & exo/endothermic
On top of the other answers: refer to the equation (in standard conditions). There are some values you can put into that equation that show a relationship between the variables that represent exothermic reactions that don't have to be spontaneous such as when is negative and the other variables represent a non-spontaneous process (e.g, low values in entropy but with a higher temperature).
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