Tell whether the free-energy changes, ΔG, for the processes listed in Problem 9.127 are likely to be positive, negative, or zero.

Verified step by step guidance

insert step 1: Understand the concept of Gibbs free energy (ΔG). It is a thermodynamic quantity that can predict the direction of a chemical reaction.

insert step 2: Recall that if ΔG is negative, the process is spontaneous; if ΔG is positive, the process is non-spontaneous; and if ΔG is zero, the system is at equilibrium.

insert step 3: Identify the processes listed in Problem 9.127. Since the specific processes are not provided here, consider common examples such as melting of ice, combustion reactions, or dissolution of salts.

insert step 4: Analyze each process based on its thermodynamic nature. For example, melting of ice at temperatures above 0°C is spontaneous, so ΔG would be negative.

insert step 5: Apply the criteria for spontaneity to each process to determine whether ΔG is positive, negative, or zero.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Gibbs Free Energy (ΔG)

Gibbs Free Energy (ΔG) is a thermodynamic potential that measures the maximum reversible work obtainable from a thermodynamic system at constant temperature and pressure. It indicates the spontaneity of a process: a negative ΔG suggests a spontaneous process, a positive ΔG indicates non-spontaneity, and a ΔG of zero signifies equilibrium.

Spontaneity of Reactions

The spontaneity of a reaction refers to whether a reaction can occur without external intervention. This is determined by the sign of ΔG; reactions with negative ΔG are spontaneous, while those with positive ΔG are non-spontaneous. Factors influencing spontaneity include enthalpy changes (ΔH) and entropy changes (ΔS) in the system.

Relationship between ΔG, ΔH, and ΔS

The relationship between Gibbs Free Energy (ΔG), enthalpy (ΔH), and entropy (ΔS) is described by the equation ΔG = ΔH - TΔS, where T is the temperature in Kelvin. This equation shows that both the heat content of the system and the disorder (entropy) influence the free energy change, thus affecting the spontaneity of the process.