AG for a spontaneous process at constant pressure and temperature is :

Question

Accepted Answer

For a spontaneous process at constant pressure and temperature, the correct answer is Option 2: $\Delta G < 0$. ### Explanation for Option 2 ($\Delta G < 0$): The Gibbs free energy change ($\Delta G$) is a thermodynamic potential that helps predict the direction of chemical reactions and processes. At constant pressure and temperature, a process is considered spontaneous if it leads to a decrease in the Gibbs free energy of the system. This is because a negative $\Delta G$ indicates that the process can occur without the input of external energy, thus being energetically favorable. Therefore, for a spontaneous process, $\Delta G$ must be less than zero ($\Delta G < 0$). ### Explanation for why the other options are incorrect: 1. **Option 1 ($\Delta G = 0$)**: - A $\Delta G$ of zero indicates that the system is at equilibrium. At equilibrium, there is no net change occurring in the system, meaning the process is neither spontaneous nor non-spontaneous. Therefore, $\Delta G = 0$ does not describe a spontaneous process. 2. **Option 3 ($\Delta G > 0$)**: - A positive $\Delta G$ indicates that the process is non-spontaneous under the given conditions. This means that the process requires an input of energy to proceed, which is the opposite of a spontaneous process. Hence, $\Delta G > 0$ is incorrect for a spontaneous process. 3. **Option 4 ($\Delta G = 1$)**: - This option is not meaningful in the context of spontaneity. The value of $\Delta G$ being exactly 1 does not provide any specific information about the spontaneity of a process. It is not a standard condition or threshold for spontaneity, making it irrelevant to the question. In conclusion, the only correct option that describes a spontaneous process at constant pressure and temperature is Option 2: $\Delta G < 0$.