[supreme]

I know entrophy increases so that excludes A and B but how do I know the sign of delta H, is there any reasoning given only this information?

[sokas]

They want you to work it out, delta G = delta H - T delta S, the reaction must be feasible. So I think the answer is C, because it is feasible at any temperature when delta H is positive, D will only happen if the temperature is high enough

[Krismas]

Surely you are breaking bonds in the liquid phase, to form free gas molecules. Breaking bonds requires energy, so delta H is positive???

[Hoofbeat]

Yes, Delta H much be positive as you are breaking the intermolecular forces.

[sokas]

but the bonds broken = the bonds formed so the delta H is the same, no?

[Hoofbeat]

No ... you are breaking the intermolecular forces between the liquid molecules and need to put energy in to evaporate it into the gas. (ie this is an endothermic process)

[sokas]

yeh i just came back to say how silly of me! I thought it over, looked into that too much at the start...now that is one mistake I can not be doing in a few weeks!

[supreme]

(Original post by sokas)
They want you to work it out, delta G = delta H - T delta S, the reaction must be feasible. So I think the answer is C, because it is feasible at any temperature when delta H is positive, D will only happen if the temperature is high enough

I did the same thing to start lol

I would like to say a massive thank you to all of you: Krismas, Hoofbeat & sokas.