Question

what will be the free energy under the following conditions; if both delta S and H are (+) if both delta S and H are (-) if delta S is (-) and H is (+) if delta S is (+) and H is (-)

Answer 1

The free energy under different conditions depends on the signs of both ΔH and ΔS. When both are positive, the process is spontaneous at high temperatures. When both are negative, the process is spontaneous at low temperatures. When ΔH is positive and ΔS is negative, the process is nonspontaneous at all temperatures. When ΔH is negative and ΔS is positive, the process is spontaneous at all temperatures.

Step-by-step explanation:

1. Both ΔH and ΔS are positive. This condition describes an endothermic process that involves an increase in system entropy. In this case, ΔG will be negative if the magnitude of the TΔS term is greater than ΔH. If the magnitude of the TΔS term is less than ΔH, the free energy change will be positive. Such a process is spontaneous at high temperatures and nonspontaneous at low temperatures.

2. Both ΔH and ΔS are negative. This condition describes an exothermic process that involves a decrease in system entropy. In this case, ΔG will be negative if the magnitude of the TΔS term is less than ΔH. If the magnitude of the TΔS term is greater than ΔH, the free energy change will be positive. Such a process is spontaneous at low temperatures and nonspontaneous at high temperatures.

3. ΔH is positive and ΔS is negative. This condition describes an endothermic process that involves a decrease in system entropy. In this case, ΔG will be positive regardless of the temperature. Such a process is nonspontaneous at all temperatures.

4. ΔH is negative and ΔS is positive. This condition describes an exothermic process that involves an increase in system entropy. In this case, ΔG will be negative regardless of the temperature. Such a process is spontaneous at all temperatures.

These four scenarios are summarized in Figure 13.8.