Question

What does it mean to say that the difference between the ΔG and ΔH values is due to entropy?

A) ΔH represents the heat exchange during a reaction, while ΔG is the Gibbs free energy change. The negative sign in ΔH means heat is released, and in ΔG, it signifies a spontaneous reaction.
B) ΔH measures the disorder of a system, while ΔG accounts for the heat transfer. The negative sign in ΔH indicates increased disorder, and in ΔG, it denotes a non-spontaneous reaction.
C) ΔH is the enthalpy change, while ΔG is the energy available to do work. The negative sign in ΔH indicates energy absorbed, and in ΔG, it signifies a spontaneous reaction.
D) ΔH reflects the heat content change, while ΔG represents the free energy change. The negative sign in ΔH means decreased heat content, and in ΔG, it indicates a spontaneous reaction.

Answer 1

The difference between ΔG and ΔH is attributed to entropy, where ΔG represents the free energy available for work after entropy is considered, and ΔH indicates the heat content change during a chemical reaction. A negative ΔG signifies a spontaneous reaction, while a negative ΔH indicates an exothermic process.

Step-by-step explanation:

When discussing the difference between ΔG (Gibbs free energy change) and ΔH (enthalpy change), we consider entropy as a key factor. ΔH represents the total heat content change of a system, primarily associated with the breaking and forming of chemical bonds. If more energy is produced in bond formation than that needed for bond breaking, the reaction is exothermic, indicated by a negative ΔH value. Conversely, ΔG reflects the amount of energy that is free to do work after accounting for the system's entropy — essentially the energy available beyond that which is 'lost' to disorder. When ΔG is negative, it signifies a spontaneous reaction, meaning the products have less free energy available and are therefore more stable.

The difference between ΔG and ΔH is essentially due to entropy. As the equation G = H - TS suggests, the Gibbs free energy change (ΔG) at a constant temperature is equal to the change in enthalpy (ΔH) minus the product of the change in entropy (ΔS) and the temperature in Kelvin (T). Therefore, a reaction may have a negative ΔG (spontaneous) even if ΔH is positive (endothermic), provided that the entropy change ΔS is sufficiently positive and the temperature is high enough to result in a negative value for ΔH - TΔS.