What does it mean for a reaction to be "thermodynamically favored?"






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Adriana Rangel 1A
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Joined: Fri Sep 29, 2017 7:04 am

What does it mean for a reaction to be "thermodynamically favored?"

Postby Adriana Rangel 1A » Sat Feb 03, 2018 1:25 pm

I saw somewhere that reactions with a negative enthalpy change are exothermic and thus more favorable than reactions with a positive enthalpy change (endothermic).
But according to the 2nd Law of Thermodynamics (states that reactions tend to go from low to high entropy) then why is a reaction with a negative enthalpy change favorable?

Ishita Monga 1B
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Re: What does it mean for a reaction to be "thermodynamically favored?"

Postby Ishita Monga 1B » Sat Feb 03, 2018 1:31 pm

Whether or not a reaction is favored is determined by deltaG. You have to use the relation deltaG=deltaH - TdeltaS in order to determine favorability. If a reaction has a negative enthalpy and entropy increases over the course of the reaction, then a negative minus a positive is still negative. Thus, deltaG would be negative which means that the reaction is favorable.

Cristina Sarmiento 1E
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Re: What does it mean for a reaction to be "thermodynamically favored?"

Postby Cristina Sarmiento 1E » Sat Feb 03, 2018 1:51 pm

Reactions that do not require energy are seen as more favorable. Since exothermic reactions release energy and endothermic reactions require energy, exothermic reactions are more favorable.

Angela G 2K
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Re: What does it mean for a reaction to be "thermodynamically favored?"

Postby Angela G 2K » Sat Feb 03, 2018 2:12 pm

Enthalpy tends to go from high enthalpy to low enthalpy, whereas entropy tends to go from low entropy to high entropy.
Delta H -, Delta S + = favored
Delta H -, Delta S - = favored at low temperatures only
Delta H +, Delta S + = favored at high temperatures only
Delta H +, Delta S - = not favored (reverse reaction is thermodynamically favored)

Shreya Ramineni 2L
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Re: What does it mean for a reaction to be "thermodynamically favored?"

Postby Shreya Ramineni 2L » Sat Feb 03, 2018 2:20 pm

Thermodynamically favorable means spontaneous, or that the reaction does not require energy in order to happen.

Phillip Winters 2F
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Re: What does it mean for a reaction to be "thermodynamically favored?"

Postby Phillip Winters 2F » Sat Feb 03, 2018 6:00 pm

A reaction if thermodynamically favorable if delta G is negative, which means that the reaction is spontaneous and thus doesn't require energy to occur

Kevin Tabibian 1A
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Re: What does it mean for a reaction to be "thermodynamically favored?"

Postby Kevin Tabibian 1A » Sun Feb 04, 2018 12:08 am

It means that it is energetically favorable and naturally occurring ( spontaneous). This is represented by a negative delta G


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