Electrochemistry oxidation-reduction reactions

Oxidation—reduction reactions, commonly called redox reactions, are an extremely important category of reaction. Redox reactions include combustion, corrosion, respiration, photosynthesis, and the reactions involved in electrochemical cells (batteries). The driving force involved in redox reactions is the exchange of electrons from a more active species to a less active one. You can predict the relative activities from a table of activities or a halfreaction table. Chapter 16 goes into depth about electrochemistry and redox reactions. 

If a chemical reaction can make electricity it should not be surprising to learn that electricity can make a chemical reaction. Using an electric current to cause a chemical reaction is called electrolysis, a technique widely used to win elements from their compounds. For example, pure sodium metal (Na) and chlorine gas (CI2) are obtained by passing electricity through molten sodium chloride (NaCl). The study of the interplay of electricity and oxidation-reduction reactions is called electrochemistry. 

Electrochemistry is the study of chemical reactions in which electricity plays a role. Some electrochemical reactions generate electricity as the reaction proceeds, while in other cases the opposite occurs—electricity drives the reaction. In either case, electrochemical reactions involve the transfer of electrons, which are the negatively charged particles surrounding an atom s nucleus. Reactions in which electrons are transferred (or appear to be transferred) from atom to atom are called oxidation-reduction reactions. 

Practically in every general chemistry textbook, one can find a table presenting the Standard (Reduction) Potentials in aqueous solution at 25 °C, sometimes in two parts, indicating the reaction condition acidic solution and basic solution. In most cases, there is another table titled Standard Chemical Thermodynamic Properties (or Selected Thermodynamic Values). The former table is referred to in a chapter devoted to Electrochemistry (or Oxidation - Reduction Reactions), while a reference to the latter one can be found in a chapter dealing with Chemical Thermodynamics (or Chemical Equilibria). It is seldom indicated that the two types of tables contain redundant information since the standard potential values of a cell reaction ( n) can be calculated from the standard molar free (Gibbs) energy change (AG" for the same reaction with a simple relationship... 

Electrochemistry is the study of the relationship between electrical energy and chemical change. It involves oxidation-reduction reactions to produce electricity, or electricity to cause an oxidation-reduction reaction. 

Master the half-reaction method before studying electrochemistry. The studies of electrochemistry rely on the recognition of oxidation and reduction, understanding the half-reactions, and possessing the ability to balance oxidation-reduction reactions. Because of these factors, the half-reaction method will be stressed in this book. 

Classification of Solvents. Solvent classification helps to identify properties useful in solvent selection for individual applications for example, the study of acid-base reactions, oxidation-reduction reactions, inorganic coordination chemistry, organic nucleophilic displacement reactions, and electrochemistry. 

The chemistry of difluoramines of the type X—NF has been studied to gain an understanding of the nature of the N—F and N—X bonds, to obtain a picture of the relative electron distributions in X—NFg compounds, and to determine the existence and stabilities of N—F radicals and ions. These compounds have been studied using electrochemistry, com-plexation, infrared spectroscopy, and theoretical calculations. Oxidation-reduction reactions have been carried out, and the effects of various environments on the N—F and N—X bonds have been investigated. The results of these studies emphasize the chemistry of difluoramine and the existence and stability of NFf+, NFg, NFg, and HgNFg+. 

Cyano metal complexes undergo a variety of oxidation-reduction reactions. One of the most studied is the fast self-exchange reaction of the [Fe(CN)4] /" anions information from this research was instrumental in establishing the outer-sphere mechanism (see Outer-sphere Reaction) for transition metal oxidation-reduction reactions (see Electrochemistry Applications in Inorganic Chemistry). The nature... 

Kostiner, Edward. Oxidation-Reduction Reactions and Electrochemistry. Sturfy Keys to Chemistry. Barron s Educational Series, Inc, 1992. 

A. Oxidation-reduction reactions versus electron transfer reactions in organic chemistry and electrochemistry... 

A. Oxidation-Reduction Reactions Versus Electron Transfer Reactions in Organic Chemistry and Electrochemistry... 

W e now turn our attention to several analytical methods that are based on oxidation/reduction reactions. These methods, which are described in Chapters 18 through 23, include oxidation/reduction titrimetry, potentiometry, coulometry, electrogravimetry, and voltammetry. Fundamentals of electrochemistry that are necessary for understanding the principles of these procedures are presented in this chapter. 

We learn much about chemical reactions from the study of electrochemistry. The amount of electrical energy consumed or produced can be measured quite accurately. All electrochemical reactions involve the transfer of electrons and are therefore oxidation-reduction reactions. The sites of oxidation and reduction are separated physically so that oxidation occurs at one location, and reduction occurs at the other. Electrochemical processes require some method of introducing a stream of electrons into a reacting chemical system and some means of withdrawing electrons. In most applications the reacting system is contained in a cell, and an electric current enters or exits by electrodes. 

Electrochemistry is the branch of chemistry that deals with the interconversion of electrical energy and chemical energy. Electrochemical processes are redox (oxidation-reduction) reactions in which the energy released by a spontaneous reaction is converted to electricity or in which electrical energy is nsed to cause a nonspontaneous reaction to occur. Although redox reactions were discnssed in Chapter 4, it is helpful to review some of the basic concepts that will come np again in this chapter. 

A battery uses the energy from an oxidation-reduction reaction to produce an electric current. This is an important illustration of electrochemistry, the study of the interchange of chemical and electrical energy. 

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