Aquatic chemistry concepts

710 Pages·2018·28.45 MB·English

by  Pankow

C D l:xem ist:ry

Aquatic Chemistry
J a m e s E P an k o^ w
Department of Environmental
Science and Engineering
Oregon Graduate Institute
Beaverton, Oregon
( g )
CRC P R E SS
Boca Raton London New York Washington, D.C.
Library of Congress Cataloging-in-Publication Data
Pankow, James F.
Aquatic chemistry concepts / James F. Pankow
p. cm.
Includes bibliographical references and index.
ISBN 0-87371-150-5
1. Water chemistry. I. Title.
GB855.P36 1991
551.46—dc20 91-18535
CIP
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Library of Congress Card Number 91-18535
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and
Werner Stumm

Contents
Part I Introduction 1
Chapter 1 Overview 3
1.1 General Importance of Aquatic Chemistry 3
1.2 Important Types of Chemical Reactions in Natural Waters 3
1.3 Concentration Scales 4
1.4 Activity and Activity Coefficients 6
1.5 Different Approaches May Be Used in Predicting Aqueous Chemistry
Speciation 9
1.5.1 Thermodynamic Equilibrium Approach 9
1.5.2 Kinetic Models 13
1.6 References 15
Chapter 2 Thermodynamic Principles 17
2.1 Free Energy and Chemical Change 17
2.1.1 Constant Pressure(femperature Systems 17
2.1.2 Constant Volume(femperature Systems 18
2.2 A Potential Energy Analog for Chemical Energy-Driven Chemical
Change 19
vii
viii Contents
2.3 The Chemical Potential and Its Relationships to Free Energy 21
2.4 Properties and Applications of the Chemical Potential 22
2.4.1 Changes in Free Energy 23
2.4.2 The Role and Nature of fL? 25
2.4.3 Standard Free Energies of Formation (~Gf) for Neutral Species 27
2.4.4 Standard Free Energies of Formation (~Gf) Values for Ionic
Species 30
2.4.5 Concentration Scales and Standard States 32
2.4.6 The Standard State and the Activity Coefficient Reference
Convention 35
2.5 Effects of Temperature and Pressure on Equilibrium Constants 38
2.6 Combining Equilibrium Expressions 40
2.7 Infinite Dilution, Constant Concentration, and "Mixed" Equilibrium
Constants 42
2.7.1 Infinite Dilution Constants 42
2.7.2 Constant Ionic Medium Constants 43
2.7.3 Mixed Constants 44
2.8 Activity Coefficient Equations 46
2.8.1 Activity Coefficient Equations for Single Ions 46
2.8.2 Activity Coefficient Equations for Neutral Species 49
2.9 References 50
Part 11 Acid/Base Chemistry 51
Chapter 3 [H+] As an Important and Meaningful Thermodynamic Variable in
Aquatic Chemistry 53
3.1 General Importance of H+ in Natural Waters 53
3.2 Question: Should We Refer to the Proton As H+ or As H 0+ in Aqueous
3
Solutions? 54
o;,
3.3 "Dissociated" Protons Exist as a Series of Species, That Is, H+, H 0+, H
3 5
Etc. in Aqueous Solution 55
3.4 References 59
Chapter 4 The Proton Balance, Electroneutrality, and Mass Balance Equations 61
4.1 The Proton Balance Equation (PBE) 61
4.1.1 PBE for Pure Water 61
Contents ix
4.1.2 PBE for a Solution of HA 61
4.1.3 PBE for a Solution of NaA 62
4.1.4 PBE for a Solution of H B 63
2
4.1.5 PBE for a Solution of NaHB 63
4.1.6 PBE for a Solution of N~B 64
4.1.7 Generalized Task Analysis for Writing the PBE for a Solution
of Interest 64
4.1.8 Writing a PBE for a Mixture 65
4.2 The Electroneutrality Equation (ENE) 66
4.3 The Mass Balance Equation (MBE) 66
4.4 The PBE, ENE, and MBE(s): Are They All Linearly Independent? 67
4.5 References 68
Chapter 5 Introduction to Quantitative Equilibrium Calculations 69
5.1 Introduction 69
5.2 General Equations for Solving for the Speciation of a Solution of the Acid
HA-No Activity Corrections 70
5.2.1 Solving for the Speciation of a Solution of the Acid HA-No
Activity Corrections, No Simplifying Assumptions 70
5.2.2 Solving for the Speciation of a Solution of the Acid HA-No
Activity Corrections, with Simplifying Assumptions 80
5.3 General Equations for Solving for the Speciation of a Solution of the Base
NaA-No Activity Corrections 91
5.3.1 Solving for the Speciation of a Solution of the Base NaA-No
Activity Corrections, No Simplifying Assumptions 93
5.3.2 Solving for the Speciation of a Solution of the Base NaA-No
Activity Corrections, with Simplifying Assumptions 95
5.4 General Equations for Solving for the Speciation of Solutions of H B, NaHB,
2
and N~B-No Activity Corrections, No Simplifying Assumptions 104
5.4.1 Solution of H B 104
2
5.4.2 Solution of NaHB 104
5.4.3 Solution of N~B 105
5.5 General Approach for Solving for the Speciation Including Activity
Corrections-Ionic Strength at Equilibrium Not Known A Priori 106
5.6 References 108