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Postby Elle_Bertuccelli_1B » Sat Jan 28, 2017 4:04 pm

When is the equation [delta]S = [delta]H / T negative? I'm confused because the solutions manual contradicts the formula sheet and I'm not sure which one is right (and how to understand this conceptually).

Stephanie Demo 2N
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Re: Entropy=enthalpy/T

Postby Stephanie Demo 2N » Sat Jan 28, 2017 4:35 pm

You can also think of that equation as ΔS = q/T as given by the second law of thermodynamics. ΔS will always be positive for a spontaneous reaction, meaning any reaction/change that happens on its own (i.e. volume of a gas expanding when the volume of the container increases). Any non-spontaneous change (i.e. condensation: gas -> liquid, making the system more ordered) will be the result of an outside force acting on it, and it will be -ΔS. Basically, ΔS will be negative whenever the system goes from a more random/disordered state to a more ordered state (another example is water freezing).

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Re: Entropy=enthalpy/T

Postby stephanieyang_3F » Sat Jan 28, 2017 5:40 pm

Elle, do you mean deltaS(surroundings)=negative deltaH(rxn)/T?

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