Question

On the basis of which two factor, one can tell whether a reaction will be spontaneous or not?

• A. The stability and state of the reactants
• B. The energy gained and the heat evolved
• C. A negative value for $\Delta$H and a positive value for $\Delta$S
• D. A positive value of $\Delta$H and a negative value for $\Delta$S
• E. The endothermic energy and the structure of the products

Answer 1

The correct option is C A negative value for $\Delta$H and a positive value for $\Delta$S

On the basis of a negative value for $\Delta H$ and a positive value for $\Delta S$ one can tell whether a reaction will be spontaneous or not.
A spontaneous reaction has negative value of $\Delta G$. A non spontaneous reaction has positive value of $\Delta G$. An equilibrium reaction has $\Delta G$ of zero.
$\Delta G=\Delta H-T\Delta S$
It is possible when $\Delta H<0$ and $\Delta S>0$, $\Delta G<0$.