Question

A certain reaction is NONspontaneous under stp conditions but becomes spontaneous at lower Ts. What conclusions may be drawn under STP conditions. The answer given to me is deltaH < 0, deltaS < 0, and deltaG > 0 I can understand why deltaG is > 0 cause of NONspontinei But I do not understand why deltaH and deltaS must also be less than 0 Please elaborate as to why the answer is as given above. why? thanks

Answer 1

​​​​​​See above, 4 condition are actually possible and your case is just one of them .

As you can see above, that ∆G can be only negative if value of T∆S is lower than -∆H . And this is only possible at lower temperature because at lower value of T , value of T∆S will be also low.