If a system is left to change spontaneously, in what state will it end?
A the same state in which it began
B the state with the lowest possible energy consistent with the state of maximum disorder
C the state with the maximum disorder
D the state with lowest possible energy
The correct answer and explanation is:
The correct answer is D: the state with the lowest possible energy.
In thermodynamics, systems tend to evolve toward a state where the energy is minimized, assuming no external influences or constraints. This is in line with the principle of the second law of thermodynamics, which states that the entropy of an isolated system will either increase or remain constant over time. Entropy is often interpreted as a measure of disorder or randomness. However, maximizing entropy does not necessarily imply the system will end up in a state of maximum disorder in a simple sense—it is more about maximizing the number of possible configurations for a given energy state.
When a system changes spontaneously, it typically moves towards a state where the available energy is used in the most efficient way. This means the system will naturally reach a configuration that allows it to have the lowest energy possible while still being consistent with the overall laws governing the system. This often corresponds to a state of maximum stability, where the system has reached equilibrium.
For example, consider a system like a gas in a container. If the gas particles are initially highly concentrated in one part of the container, they will spontaneously spread out and distribute more evenly. This movement toward uniform distribution lowers the energy state of the system, as the particles are no longer crowded together in a way that would increase internal energy. In the end, the system reaches a state of equilibrium, where energy is as minimized as possible given the constraints, and entropy is maximized within that energy context.
Thus, the spontaneous change leads the system to its most stable and energy-efficient configuration, which is generally the lowest energy state achievable for that system.