Change in enthalpy






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melissa_dis4K
Posts: 106
Joined: Fri Sep 28, 2018 12:28 am

Change in enthalpy

Postby melissa_dis4K » Tue Feb 26, 2019 12:29 am

Why does an endothermic (positive delta H) not favor the forward process?

Jack DeLeon 1B
Posts: 30
Joined: Fri Sep 28, 2018 12:20 am

Re: Change in enthalpy

Postby Jack DeLeon 1B » Tue Feb 26, 2019 1:15 am

it doesn't always favor the reverse reaction. When enthalpy is positive and entropy is negative, then the reaction favors the reverse. However when enthalpy is positive and entropy is also positive, the sign of Delta G depends on the temperature. You would use the equation "DeltaG= DeltaH - T(DeltaS)" to figure out whether the temp makes Delta G positive or negative.

Christina Chang 1C
Posts: 34
Joined: Thu May 10, 2018 3:00 am

Re: Change in enthalpy

Postby Christina Chang 1C » Tue Feb 26, 2019 1:16 am

Endothermic would not be favorable because positive entropy is favorable (since more disorder is generally created) and as a result, if you want free energy to be negative and entropy is positive, enthalpy would have to be negative at a high temperature to guarantee a spontaneous reaction (negative free energy). Hope that made sense!


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