Question

At what temperature is the dissociation spontaneous?
(∆G = ∆H – T∆S)

Answer 1

The dissociation reaction, like any reaction, becomes spontaneous when delta G is negative. That happens whenever the temp * delta entropy (S) term is greater than the H term for enthalpic energy.

To get an expression for when that change takes place, set the equation equal to zero and solve for T.

0 = H - T*delta S
H = T*deltaS

T = H / deltaS.

Hope that's helpful.