posted by Anonymous .
For the solvation of borax in water, would delta Ssys increase or decrease in the reaction?
I was thinking that since delta H is positive then delta Ssys is negative but I am not completely sure.
The ions making up borax have much more freedom of movement in solution. Also, the chemical species in solution are more mixed up than they would be in separate phases. What would that do to the total entropy of system?
So would it be positive then since the a positive S means more disorder?
I gave you the background information needed to draw your own conclusions.
Yes. It would be positive. Given the formula deltaG= delta(H)-Tdelta(S), a positive H minus Tdelta(S) with a low temperature has the ability to make delta G negative, but the greater the temperature, the more negative delta G becomes. The more negative delta G is, the more spontaneous the reaction is. If delta S was negative then delta G would only get larger, and therefore less spontaneous. Since Borax is represented by the following reaction, we know that it is spontaneous.
Na2B4O7·10H2O(s) <-> 2Na+(aq)+ B4O5(OH)4^2-(aq) + H20(l)
You'll have less entropy in a solid, so the reaction will be spontaneous in the forward direction.