Under given conditions, if a change is spontaneous in one direction, it is not spontaneous in the other. A. True B. False
The correct answer and explanation is:
The correct answer is A. True.
In thermodynamics, the spontaneity of a process is determined by the Gibbs free energy change (ΔG). A process is considered spontaneous if the change in Gibbs free energy is negative (ΔG < 0). If a process is spontaneous in one direction, the reverse process will have a positive Gibbs free energy change (ΔG > 0), meaning it is non-spontaneous.
This principle is derived from the second law of thermodynamics, which states that the total entropy of the system and surroundings must increase for a process to be spontaneous. When a change occurs in one direction, it leads to an increase in the overall entropy, making the process spontaneous. However, reversing the process would decrease the entropy, making it non-spontaneous.
For example, consider the phase transition from liquid water to ice. Melting ice into liquid water is a spontaneous process at temperatures above 0°C because the entropy of the system increases as the solid structure breaks down into a liquid. However, freezing liquid water to form ice is non-spontaneous at temperatures above 0°C, because it results in a decrease in entropy. The reverse process (freezing) only becomes spontaneous at temperatures below 0°C.
In summary, spontaneity is direction-dependent. If a process is spontaneous in one direction, it will not be spontaneous in the opposite direction under the same conditions.