Chapter 18, Problem 18.85QP

(a)

Interpretation Introduction

Interpretation:

Given two carboxylic acids, the standard free $(\Delta G°)$ values has to be calculated at $25°C$.

Concept Information:

Free energy$(\text{ΔG})$: In thermodynamics free energy or Gibbs free energy is the energy that is used to express the total energy content of a system.  According to second law of thermodynamics, in all spontaneous process is associated with the decrease in free energy of the system.  That is the change in free energy will be negative.

Free energy (Gibbs free energy) is the term that is used to explain the total energy content in a thermodynamic system that can be converted into work.  The free energy is represented by the letter $\text{G}$.  All spontaneous process is associated with the decrease of free energy in the system.  The standard free energy change ${\text{(ΔG}}^{\text{°}}{}_{\text{rxn}})$

  $\begin{array}{l}{\text{ΔG}}^{\text{0}}\text{=-RTln}\text{K}\\ \text{ΔG}=Freeenergy\\ {\text{ΔG}}^{\text{0}}=S\tan dard-statefreeenergy\\ \text{R}\text{=}\text{Gas}\text{Constant}(\text{0}\text{.0826}\text{l}\text{.atm/K}\text{.atm})\\ T=\text{Temprature}\text{273}\text{K}\\ \text{K=}\text{Equlibrium}\text{Constant}{\text{(K}}_{\text{P}}\text{and}{\text{K}}_{\text{C}}\text{)}\end{array}$

(b)

Interpretation Introduction

Interpretation:

Given ionization reaction which is the dominant term in determining the value of ${\text{ΔG}}_{}^{\text{o}}$

Concept Information:

Free energy (Gibbs free energy) is the term that is used to explain the total energy content in a thermodynamic system that can be converted into work.  The free energy is represented by the letter $\text{G}$.  All spontaneous process is associated with the decrease of free energy in the system.  The standard free energy change ${\text{(ΔG}}^{\text{°}}{}_{\text{rxn}})$ is the difference in free energy of the reactants and products in their standard state.

${\text{ΔG}}^{\text{°}}{}_{\text{rxn}}\text{=}\sum {\text{nΔG}}_{\text{f}}{}^{\text{°}}\text{(Products)-}\sum {\text{nΔG}}_{\text{f}}{}^{\text{°}}\text{(Reactants)}$

(c)

Interpretation Introduction

Interpretation:

Given ionization process in which process contribute to $\Delta H°$, it should be determined. 

Concept Information:

Enthalpy changes: The changes in enthalpy that accompanies the formation of one mole of the compound at its normal state from its constituent elements in their standard state.

Bronsted's definition is based on the chemical reaction that occurs when both acids and bases are added with each other. In Bronsted's theory acid donates proton, while base accepts proton.

(d)

Interpretation Introduction

Interpretation:

The $T\Delta S°$ term is more negative for acetic acid, the correct reason should be explained.

Concept Information:

Enthalpy changes: The changes in enthalpy that accompanies the formation of one mole of the compound at its normal state from its constituent elements in their standard state.

In thermodynamics, free energy (Gibbs free energy) is the term that is used to explain the total energy content in a thermodynamic system that can be converted into work.  The free energy is represented by the letter G.

The equation given below helps us to calculate the change in free energy in a system.

$\text{ΔG = }\Delta {\rm H}\text{- T}\Delta \text{S}$