All questions of Gibbs Free Energy Changes for EmSAT Achieve Exam

Understanding Free Energy Change in Chemical Processes
In spontaneous chemical processes, the change in free energy is a crucial indicator of whether a reaction can occur without external intervention.
What is Free Energy?
- Free energy, often represented as G, is a thermodynamic quantity that combines enthalpy and entropy.
- It helps predict the direction of chemical reactions.
Spontaneous Processes
- A spontaneous process is one that occurs naturally under specific conditions without needing to be driven by an external force.
- For such processes, the system tends to move towards equilibrium.
Free Energy Change (ΔG)
- The change in free energy (ΔG) is calculated as the difference in free energy between the products and reactants.
- The sign of ΔG determines the spontaneity of the reaction.
Negative Free Energy Change
- If ΔG is negative (ΔG < 0),="" it="" indicates="" that="" the="" reaction="" can="" occur="" />
- A negative value signifies that the products have lower free energy compared to the reactants, meaning energy is released during the process.
Implications of ΔG
- A negative ΔG implies that the reaction is thermodynamically favorable.
- This release of energy often results in increased entropy, a natural tendency for systems to achieve greater disorder.
Conclusion
- Therefore, for spontaneous chemical processes, the free energy change is indeed negative, confirming that option 'B' is correct.
- Understanding this concept is vital in predicting reaction behavior in chemistry.

A spontaneous process is the time-evolution of a system in which it releases free energy and it moves to a lower, more thermodynamically stable energy state. For cases involving an isolated system where no energy is exchanged with the surroundings, spontaneous processes are characterized by an increase in entropy

Extensive Property:

An extensive property is a physical property of a system that depends on the amount of substance present in the system. In other words, extensive properties are additive and scale with the size or amount of the system. The value of an extensive property changes when the size or amount of the system changes.

Explanation:

Out of the given options, the correct answer is option 'B' - Entropy.

Entropy is a measure of the disorder or randomness of a system. It is a thermodynamic property that quantifies the number of microscopic configurations that a system can have. Entropy is an extensive property because it depends on the size or amount of the system.

Comparison with Other Options:

a) Specific Heat Capacity:
Specific heat capacity is the amount of heat energy required to raise the temperature of a substance by a certain amount. It is an intensive property because it does not depend on the amount of substance present. The specific heat capacity of a substance remains the same regardless of the size or amount of the substance.

b) Entropy:
As mentioned earlier, entropy is an extensive property as it depends on the amount of substance present in the system. If the system size or amount changes, the entropy of the system will also change proportionally.

c) Temperature:
Temperature is an intensive property because it does not depend on the amount of substance present. The temperature of a substance remains the same regardless of the size or amount of the substance.

d) Refractive Index:
Refractive index is a measure of how light propagates through a medium. It is an intensive property because it does not depend on the amount of substance present. The refractive index of a substance remains the same regardless of the size or amount of the substance.

Conclusion:

Among the given options, entropy is the only extensive property. It is a thermodynamic property that depends on the amount of substance present in the system. The other options, specific heat capacity, temperature, and refractive index, are intensive properties that do not depend on the amount of substance present.

The second law of thermodynamics states that for any spontaneous process, the overall ΔS must be greater than or equal to zero; yet, spontaneous chemical reactions can result in a negative change in entropy.

The greater the randomness in a system, greater is its entropy. The randomness is greater in liquid state as compared to solid state so the entropy increases when ice melts into water.

The entropy of vaporization is the increase in entropy upon vaporization of a liquid. This is always positive, since the degree of disorder increases in the transition from a liquid in a relatively small volume to a vapor or gas occupying a much larger space.

A state function is the property of the system whose value depends only on the initial and final state of the system and is independent of the path. It is a state function because it is independent of the path. Heat (q) and work (W) are not state functions being path dependent.