entropy, enthalpy, spontaneity...

[Ice-cream]

For the dissociation reaction of the acid HF:

 

HF(aq) --> H+(aq) + F-(aq)

 

DeltaS is observed to be negative. The BEST explanation for this is:

 

a) This is the expected result since each of the HF molecule produces two ions when it dissociates.

b) Hydration of the ions produces the negative value of deltaS.

c) The reaction is expected to be exothermic and thus deltaS should be negtaive.

d) The reaction is expected to be endothermic and thus deltaS should be negative.

e) None of these explain the negative value of deltaS.

 

Can someone please help me with this question?

 

What I know so far is that if deltaS is negative, the reaction must not be spontaneous.

 

I know the formula deltaS(surroundings) = -deltaH / temperature....but that is for the entropy of the surroundings and not for the system....so I think maybe c) and d) are probably both incorrect because the deltaS they are referring to should be for the system.

 

I really have no idea what a) and b) are talking about....

 

Any help would be greatly appreciated. Thanks