If delta H is negative, will a reaction always be spontaneous?

Question

can someone please explain me in a short sentence how to answer this question? thanks....

Answer 1

A little chart my general chemistry professor gave me when I took his class that's very useful.

ΔH. . . . . .ΔS..........Spontaneous?

Exo (-).......ΔS>0......(+)yes, ΔG<0

Exo (-).......ΔS<0......(-)yes, if TΔS < |ΔH|

Endo (+)....ΔS>0......(+)yes, if TΔS > ΔH

Endo (+)....ΔS<0......(-)no, ΔG>0



ΔH = enthalpy ΔS = entropy ΔG = Gibbs energy

T= temperature exo = exothermic endo = endothermic



I say Gibbs energy because according to my professor, nothing in life is ever free. Enjoy =D

Answer 2

Negative

Answer 3

Look at it this way: Regardless of whether standard enthalpy is positive or negative (or entropy, for that matter), if you start with all reactants and no product, *some* product is gonna form to establish equilibrium, and if you start with all product and no reactants, *some* reactants are gonna form. Spontaneity depends on concentration and temperature, too, not just on enthalpy and entropy.

Answer 4

No, it also depends on the entropy change. It's the combination of the two that decides whether a reaction will be spontaneous or not.

Answer 5

This Site Might Help You.



RE:

If delta H is negative, will a reaction always be spontaneous?

can someone please explain me in a short sentence how to answer this question? thanks....