In which set of conditions would result in a spontaneous reaction? a. an exothermic reaction; a decrease in entropy; at high temperatures b. an exothermic reaction; an increase in entropy; at any temperature c. an endothermic reaction; an increase in entropy; at low temperatures d. an endothermic reaction; a decrease in entropy; at any temperature

The correct answer is Option B.

Explanation:

For a reaction to be spontaneous, the Gibbs' Free Energy must be negative.

Equation for Gibbs Free energy is given by:

Where, G = Gibbs free energy

H = Enthalpy of the reaction

T = Temperature of the system

S = Entropy of the system

Sign convention for all the quantities:

For H: It is negative for exothermic reactions and positive for endothermic reactions

For S:  It is positive when there is increase in entropy and it is negative when there is decrease in entropy.

If we want G to be negative, the conditions necessary are:

The product of temperature and entropy must be positive and that will be positive when there is increase in entropy at any temperature.

Hence, the correct answer is Option B.