hey guys,

I'm stuck on this question:

Rubidium has a heat of vaporization of 69.0kj/mol at its boiling point (686 degrees celcius).

Calculate ?S for this process, Rb(l)------->Rb(g), at 1 atm and 686 degrees celcius.

Ok, I think the question wants the ?S of the universem I'm not sure, what does it mean when they just say "?S"?

So I first tried to calculate the ?S of the system and the ?S of the surronding.

converted 69.kj/mol to .069 j/m. Then subtracted reactants from products in above equation = .069-.069=0. So the ?S for the system is 0...I think?

and I don't really know how to proceeed with the surrounding. I have a formula here, but ?H was not provided, and I can't seem to find it.

help would be greatly appreciated, thanks.