Spontaneous Processes

Definition

Spontaneous processes are natural, self-driven changes that occur in a system without the need for external energy input. They are characterized by an increase in the disorder or randomness of the system, as described by the Second Law of Thermodynamics.

5 Must Know Facts For Your Next Test

1. Spontaneous processes occur naturally and do not require external energy input to proceed.
2. The spontaneity of a process is determined by the change in Gibbs free energy, with negative values indicating a spontaneous process.
3. Spontaneous processes are associated with an increase in the entropy or disorder of the system, as described by the Second Law of Thermodynamics.
4. Endothermic reactions, such as the melting of ice, can be spontaneous if the increase in entropy outweighs the energy required for the process.
5. The tendency of systems to move towards a state of higher entropy is a fundamental driver of spontaneous processes in nature.

Review Questions

• Explain how the concept of entropy is related to the spontaneity of a process.
  • The spontaneity of a process is closely linked to the change in entropy of the system. Spontaneous processes are characterized by an increase in the disorder or randomness of the system, as described by the Second Law of Thermodynamics. This increase in entropy is a key factor in determining the spontaneity of a process, as systems tend to move towards states of higher entropy. The greater the increase in entropy, the more likely a process is to occur spontaneously, without the need for external energy input.
• Describe how Gibbs free energy can be used to predict the spontaneity of a process.
  • Gibbs free energy is a thermodynamic quantity that combines the concepts of energy and entropy, and is used to determine the spontaneity and feasibility of a process. The change in Gibbs free energy, $\Delta G$, is the key indicator of spontaneity. If $\Delta G$ is negative, the process is spontaneous and will occur naturally. If $\Delta G$ is positive, the process is non-spontaneous and will require an input of energy to proceed. The magnitude of $\Delta G$ also provides information about the extent of the spontaneity, with larger negative values indicating a more favorable and spontaneous process.
• Analyze the role of equilibrium in the context of spontaneous processes.
  • Spontaneous processes often lead a system towards a state of equilibrium, where the net change in the system is zero, and the system is in a stable, balanced condition. At equilibrium, the forward and reverse reactions occur at equal rates, and the system is no longer undergoing spontaneous change. However, the system may still be in a state of dynamic equilibrium, with continuous spontaneous processes occurring at the molecular level, but with no net change in the overall state of the system. Understanding the relationship between spontaneous processes and equilibrium is crucial for predicting the behavior of chemical and physical systems.

Related terms

Entropy: A measure of the disorder or randomness in a system, which tends to increase over time in spontaneous processes.

Gibbs Free Energy: A thermodynamic quantity that combines the concepts of energy and entropy, and determines the spontaneity and feasibility of a process.

Equilibrium: The state of a system where the net change is zero, and the system is in a stable, balanced condition.