Need help with Gibbs free Energy!

[kfcman289]

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The enthalpy part of the equation just confuses me so much. I had a question where it asked if a solid to aqueous reaction would lower its free energy if the temperature was increased.

AgCl(s)------- Ag+ (aq) + Cl-(aq)


Obviously, its easy to say yes it would because the T part would go up and S should decrease as well. But, wouldn't enthalpy go up as well with temperature? If H= U + PV, and we assume that P and V are the same because there are not any gases in this reaction, U must have gone up if temperature went up, correct?

 

[Cawolf]

The entropy in that reaction would increase - one molecule is becoming two.

S(formation)

AgCl(s) = 96.2 J/molK
Ag+ (aq) = 72.7 J/molK
Cl- (aq) = 56.5 J/molK

We can show that S(products) - S (reactants) = 33 J/molK --------> a net increase in entropy for the system.

I do agree that the enthalpy will also increase in the system.

As for the rest of your question - I don't have a great answer off the top of my head but I just wanted to mention the entropy thing.

 

[MedHopeful20134]

When something becomes more stable, its free energy decreases. Hence, if you dissolve something, it would dissociate into ions (a more stable state).