Spontaneity of Exo and Endo reactions






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AditiSax
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Joined: Fri Sep 28, 2018 12:20 am

Spontaneity of Exo and Endo reactions

Postby AditiSax » Sun Feb 03, 2019 4:59 pm

Are exothermic reactions more likely to be spontaneous than endothermic reactions?

Cienna Henry 1J
Posts: 61
Joined: Fri Sep 28, 2018 12:15 am
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Re: Spontaneity of Exo and Endo reactions

Postby Cienna Henry 1J » Sun Feb 03, 2019 5:08 pm

Yes but not all spontaneous reactions are exothermic.

Anjali_Kumar1F
Posts: 62
Joined: Fri Sep 28, 2018 12:25 am

Re: Spontaneity of Exo and Endo reactions

Postby Anjali_Kumar1F » Sun Feb 03, 2019 5:44 pm

Why aren't all exothermic reaction spontaneous?

kateminden
Posts: 63
Joined: Fri Sep 28, 2018 12:24 am

Re: Spontaneity of Exo and Endo reactions

Postby kateminden » Sun Feb 03, 2019 5:45 pm

Generally, exothermic reactions are more likely to be spontaneous than endothermic, but there are some instances when endothermic reactions are spontaneous. If the change in entropy at a given temperature is sufficient to overcome the unfavorable change in enthalpy, then the reaction will spontaneously occur, therefore making it a spontaneous endothermic reaction.

ran2000
Posts: 66
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Re: Spontaneity of Exo and Endo reactions

Postby ran2000 » Fri Feb 08, 2019 2:11 pm

Yes. But spontaneity is largely dependent on the 3 factors: enthalpy change, entropy change and temperature. Based on the values of each, the gibbs free energy is either positive or negative. Usually, however, exothermic reactions are more likely to be spontaneous because is H is less than 0, and since S is usually positive for exothermic reactions- G= negative. G= H-TS where H is negative and S is positive. Thus, G is usually negative and the reaction is spontaneous.


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