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Question 4.37 in O-Chem Book

Posted: Sun Feb 28, 2016 1:32 pm
by HoganFenster2E
When commenting on the possible values for standard enthalpies of activation (delta H) and standard entropies of activation (delta S) why are delta H values always unfavorable positive and why are delta S values often unfavorable negative? The book answer key gives a little explanation but I don't really understand it. Also, it says the delta S values are often unfavorable negative because there is usually a decrease in entropy, but wouldn't it be favorable?

Re: Question 4.37 in O-Chem Book

Posted: Sun Feb 28, 2016 2:11 pm
by Chem_Mod
If you think about it, delta G^double dagger is always positive for the TS peaks right? If you remember delta G = deltaH -TdeltaS, then you will see that for delta G to be positive, enthalpy and entropy are usually positive and negative, respectively (for the TS).