# Chemistry, Thermodynamics

posted by
**Taasha** on
.

I have a couple questions:

1. When analyzing which has greater entropy, do you look at the larger number or the smaller number?

2. What two things must be met for a reaction to be spontaneous under ALL temperature conditions?

3. If heat is in the products, the equation is exothermic right? If heat is in the reactants, the equation is endothermic?

I don't understand question #1.

#2. delta G = delta H - T*delta S

so if delta H is negative and delta S is positive, delta G MUST be negative and the reaction will be spontaneous at all temperatures.

#3. right.

Thanks!

For number 1, for example, if Br2 (l) has a delta S of 152.5 and Br2 (g) has a delta S of 245.4, which one has the greater entropy? Br2 (g) because the number is larger?

Is the delta S of NaCl (aq) included in your table? I was looking for it and I couldn't find it anywhere!

S^{o} at 298.15 (solid) NaCl is 72.38 J/mol*K. Note S is in J while delta G and delta H are in kJ/mol.

I am so sorry, and maybe it is because it is so late, but I'm not understanding anything you previously said. First of all, did you answer the question: For number 1, for example, if Br2 (l) has a delta S of 152.5 and Br2 (g) has a delta S of 245.4, which one has the greater entropy? Br2 (g) because the number is larger? Maybe I just need to stop and look at this stuff tomorrow :)

Secondly, is delta S of NaCl (aq) 298.15? What is 72.38 J/mol*K?

Once again, I am really sorry

You posted no questions about Br2 gas or liquid so I haven't answered anything about that. Second, the 298.15 Kelvin is the TEMPERATURE at which I gave you S^{o} of 72.38 J/mol*K for NaCl (solid). Aqueous NaCl is 115.5 J/mol*K at 298.15 Kelvin