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Home Q & A Board Science-Related Homework Help Chemistry (Moderator: Laser_3)
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firegirl2012 firegirl2012
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11 years ago
If a chemical reaction is exothermic, will it be spontaneous under all conditions?
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#1
11 years ago
That depends on its entropy change. Remember that spontaneous reactions have a DG <0 and that DG = DH - TDS (D = delta).

So, an exothermic reaction that increases in entropy will always be spontaneous. But one which has a negative entropy change will be spontaneous at lower temperatures but not spontaneous at higher temperatures.
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11 years ago
The simple answer is: no!  There is always an activation energy necessary to "kick-off" a reaction.  Once the reaction starts, the exotherm keeps the reaction going.  You can sometimes lower the activation energy using a catalyst.
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mickeyKmickeyK
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11 years ago
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