Explain why each of the following is incorrect:

Question

(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?

Answer 1

So when there's a spontaneous reaction, deltaS is > 0 , I confused that with increase. I still don't see how it's incorrect

Answer 2

(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.

Thank you

Answer 3

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.

Answer 4

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

Answer 5

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.

Answer 6

I get it now, thanks again Bob