Using values of ΔfH° and S°, calculate the standard molar free energy of formation, ΔfG°, for each of the following:
- (a) Ca(OH)2(s)
- (b) Cl(g)
- (c) Na2CO3(s)
Compare your calculated values of ΔfG° with those listed in Appendix L. Which of these formation reactions are predicted to be product-favored at equilibrium at 25 °C?
(a)
Interpretation:
The the standard molar free energy for formation of
Concept introduction:
The Gibbs free energy or the free energy change is a thermodynamic quantity represented by
The sign of
Answer to Problem 34PS
The standard molar energy of formation for
Explanation of Solution
The standard molar energy of formation for
Given:
The Appendix L referred for the values of standard entropies and enthalpies.
The enthalpy change is expressed as,
Substituting the values,
The entropy change is expressed as,
Substituting the values,
Now,
Substitute the value of
The value in Appendix L is
The value of free energy change is negative. Thus, the reaction is product-favored at equilibrium.
(b)
Interpretation:
The the standard molar free energy for formation of
Concept introduction:
The Gibbs free energy or the free energy change is a thermodynamic quantity represented by
The sign of
Answer to Problem 34PS
The standard molar energy of formation for
Explanation of Solution
The standard molar energy of formation for
Given:
The Appendix L referred for the values of standard entropies and enthalpies.
The enthalpy change is expressed as,
Substituting the respective values,
The entropy change is expressed as,
Substituting the respective values,
Now,
Substitute the value of
The value in Appendix L is
The value of free energy change is positive. Thus, the reaction is reactant-favored at equilibrium.
(c)
Interpretation:
The the standard molar free energy for formation of
Concept introduction:
The Gibbs free energy or the free energy change is a thermodynamic quantity represented by
The sign of
Answer to Problem 34PS
The standard molar energy of formation for
Explanation of Solution
The standard molar energy of formation for
Given:
The Appendix L referred for the values of standard entropies and enthalpies.
The enthalpy change is expressed as,
Substituting the values,
The entropy change is expressed as,
Substituting the values,
Now,
Substituting the value of
The value in Appendix L is
The value of free energy change is negative. Thus, the reaction is product-favored at equilibrium.
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Chapter 18 Solutions
Chemistry and Chemical Reactivity - AP Edition
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