Standard Potentials in Aqueous Solution

Allen J. Bard, Roger Parsons, Joseph Jordan

• Publisher: CRC Press
• Year: 2017
• ISBN:
  9781351414739
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Molecular Biology
• Index: Biological Sciences

The best available collection of thermodynamic data!The first-of-its-kind in over thirty years, this up-to-date book presents the current knowledgeon Standard Potentials in Aqueous Solution.Written by leading international experts and initiated by the IUPAC Commissions onElectrochemistry and Electroanalytical Chemistry, this remarkable work begins with athorough review of basic concepts and methods for determining standard electrodepotentials. Building upon this solid foundation, this convenient source proceeds to discussthe various redox couples for every known element.The chapters of this practical, time-saving guide are organized in order of the groups ofelements on the periodic table, for easy reference to vital material. AND each chapteralso contains the fundamental chemistry of elements... numerous equations of chemicalreactions... easy-to-read tables of thermodynamic data... and useful oxidation-statediagrams.Standard Potentials in Aqueous Solution is an ideal, handy reference for analytical andphysical chemists, electrochemists, electroanalytical chemists, chemical engineers, biochemists, inorganic and organic chemists, and spectroscopists needing information onreactions and thermodynamic data in inorganic chemistry. And it is a valuable supplementarytext for undergraduate- and graduate-level chemistry students.

1

Standard Electrode Potentials: Units, Conventions, and Methods of Determination^*

ROGER PARSONS^† Laboratoire d'Electrochimie Interfaciale du CNRS, Meudon, France

I. Symbols

The standard electrode potential is a physical quantity and, like all physical quantities, it is the product of a numerical value (a pure number) and a unit (volt). It is represented by the symbol E°, the superscript indicating the standard nature of the quantity. More precisely, E° in the context of this book is the standard potential of a cell reaction when that reaction involves the oxidation of molecular hydrogen to solvated protons. When necessary the reaction will be indicated in parentheses or brackets after the symbol E°, for example,

Eo(Zn2+(aq)+H2(g)+2H+(aq)+Zn(s))⁢(1.1)

which may be abbreviated [assuming that the reaction H(g) → 2H⁺ (aq) + 2e^” is always present]

Eo(Zn2+(aq)+2e−→Zn)⁢(1.2)

or

Eo(Zn2+/Zn)⁢(1.3)

Other important physical quantities to be used in this work are:

T Thermodynamic temperature

G Molar Gibbs energy

S Molar entropy

C_p Molar heat capacity

H Molar enthalpy

x_A Mole fraction of species A

m_A Molality of species A (number of moles of A dissolved in 1 kg of solvent

c_A Concentration of species A, also indicated as [A] (number of moles of A contained in 1 liter of solution, formerly called molarity)

p_A Partial pressure of species A

pA* Fugacity of species A

a_A Activity of species A

K Thermodynamic equilibrium constant of a reaction

n Charge number of a cell reaction [see Section III, following (1.8)]

II. Units and Constants

The units of energy and potential employed are those adopted by the Confèrence Gènèrale des Poids et Mesures and known as SI (Système International) units. The primary energy unit is the joule, defined in terms of the SI base units, the kilogram, meter, and second:

1joule≡1J≡1kgm2s−2⁢(1.4)

Many data in the literature are quoted in calories. They have been converted into joules using the conversion factor 4.1840 J cal⁻¹. Also, 1 eV = 1.6021892 × 10⁻¹⁹ J. The unit of electrical potential difference is the volt, defined in terms of these SI base units together with the ampere:

1volt≡1V≡1kgm2s−3A−1≡1JA−1s−1⁢(1.5)

Pressure, molality, and concentration units have most usually been

1atmosphere≡101325Nm−2(Pa)1molkg−1(massofsolvent)1molL−1=1moldm−3(valumeofsolution)

and these will continue to be used here. Conversion of pressure or concentration units to the coherent SI units of 1 N m⁻² and 1 mol m⁻³ involves recalculation of the values of standard thermodynamic quantities [se...