posted by Robert on .
Explain why each of the following is incorrect:
(a) Entropy increases in all spontaneous reactions.
Wouldn't (a) be actually correct? Because when there's a spontaneous reaction, you have less stable molecules and more disorder. It will be lower in some reactions than in others, but doesn't it always increase when a reaction favors spontaneity?
So when there's a spontaneous reaction, deltaS is > 0 , I confused that with increase. I still don't see how it's incorrect
(b) deltaG < 0 , are product-favored and occur with rapid transformation of reactants to products.
HOw is this incorrect? deltaG < 0 is product-favored and is rxn forward.
For dS, it depends upon what dS you are talking about. dS is positive(increases) for all spontaneous reactions IF you are talking about total dS; i.e.,
dSsurrounds + dSsystem = positive.
For dG, the first part is correct about < 0; the last part makes it incorrect. dG says nothing about how fast a reaction will occur.
Thanks Bob! As for deltaS, it just says Entropy increases in all spontaneous reactions, there's nothing more specified, so I assumed that it was deltaS and not deltaSuniverse
Regarding dS for the system, there are some reactions that occur spontaneously in which dS decreases. Since
dG = dH - TdS, the delta H part may override the TdS part just as in endothermic reactions the TdS part can overcome the dH part.
I get it now, thanks again Bob