   Chapter 21, Problem 64PS

Chapter
Section
Textbook Problem

The overall reaction involved in the industrial synthesis of nitric acid is NH 3 ( g ) + 2  O 2 ( g ) → HNO 3 (aq) + H 2 O( l ) Calculate ΔrG° for this reaction and its equilibrium constant at 25°C.

Interpretation Introduction

Interpretation:

The free energy change for the given reaction has to be calculated.

Concept introduction:

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by ΔG. The expression for the free energy change is:

ΔrG°=nΔfG°(products)nΔfG°(reactants)

ΔG is also related to the equilibrium constant K by the equation,

ΔrG=RTlnKp

The rearranged expression is,

Kp=eΔrGRT

Explanation

The ΔrG° and the equilibrium constant for the reaction of ammonia and oxygen is calculated below.

Given:

Refer to Appendix L for the values of standard free energies.

The standard free energy of HNO3(aq) is 111.25 J/Kmol.

The standard free energy of H2O(l) is 237.15 J/Kmol.

The standard free energy of NH3(g) is 16.37 J/Kmol.

The standard free energy of O2(g) is 0 J/Kmol.

The balanced chemical equation is:

NH3(g)+2O2(g)HNO3(aq)+H2O(l)

The ΔrG° can be calculated by the following expression,

ΔrG°=nΔfG°(products)nΔfG°(reactants)=[[(1 mol HNO3(aq)/mol-rxn)ΔfG°[HNO3(aq)]+(1 mol H2O(l)/mol-rxn)ΔfG°[H2O(l)]][(1 mol NH3(g)/mol-rxn)ΔfG°[NH3

Still sussing out bartleby?

Check out a sample textbook solution.

See a sample solution

The Solution to Your Study Problems

Bartleby provides explanations to thousands of textbook problems written by our experts, many with advanced degrees!

Get Started 