Question

asap please
According to the Gibbs free energy equation, G= H-T S, when is a
reaction always spontaneous?

A. When A His positive and AS is negative

B. When A His negative and AS is positive

C. When A Hand AS are both negative

D. When A Hand AS are both positive​

Answer 1

Answer:

When $\Delta H^o < 0$ and $\Delta S^o > 0$

Explanation:

The spontaneity of a reaction can be determined by the sign of the Gibbs free energy change. For a spontaneous reaction, the change in Gibbs free energy should be negative, meaning:

$\Delta G^o = \Delta H^o - T\Delta S^o < 0$

Since the temperature value here corresponds to the absolute temperature, this implies that T > 0 for any T. Therefore, to have a negative difference for any temperature value, the first term, the change in enthalpy, should be negative and the change in entropy should be positive, so that we always subtract a positive number from a negative number. This corresponds to a negative value in $\Delta G^o$.