Question

"When predicting the Sign of ∆S for a reaction, what are two things to consider? Driving forces for spontaneous processes (reactions) rely on what 2 factors?"

a) Temperature and pressure
b) Enthalpy change and Gibbs free energy change
c) Initial concentration and rate of reaction
d) Heat transfer and work done on the system

Answer 1

In predicting the Sign of ∆S for a reaction, consider if the process is endothermic or exothermic, and an increase or decrease in entropy. The driving forces are enthalpy change and Gibbs free energy change, with enthalpically or entropically driven reactions being influenced by the T∆S term.

Step-by-step explanation:

When predicting the Sign of ∆S for a reaction, two important considerations are:

• Whether the process is endothermic or exothermic.
• Whether the process is accompanied by an increase or decrease in entropy.

The driving forces for spontaneous processes rely on two main factors:

1. Enthalpy change (∆H)
2. Gibbs free energy change (∆G), which incorporates temperature due to the ∆G equation:∆G = ∆H - T∆S.

While enthalpically driven reactions depend on the ∆H term, entropically driven reactions rely more on the T∆S term. The total entropy change (∆Stotal) is the definitive criterion for spontaneous change.

Answering the student's question, the correct choice is: b) Enthalpy change and Gibbs free energy change. These factors are foundational in understanding whether a reaction will proceed without additional energy input (be spontaneous).