Chemistry
Electrochemistry
Electrochemistry is the study of the relationship between chemical reactions and electricity. It involves the movement of electrons in chemical reactions, and the conversion of chemical energy into electrical energy, and vice versa. Key concepts in electrochemistry include redox reactions, electrolysis, and electrochemical cells, which have applications in batteries, corrosion prevention, and industrial processes.
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10 Key excerpts on "Electrochemistry"
eBook - PDFElectrochemical Methods
Fundamentals and Applications
- Allen J. Bard, Larry R. Faulkner(Authors)
- 2012(Publication Date)
- Wiley(Publisher)
C H A P T E R 1 INTRODUCTION AND OVERVIEW OF ELECTRODE PROCESSES 1.1 INTRODUCTION Electrochemistry is the branch of chemistry concerned with the interrelation of electri- cal and chemical effects. A large part of this field deals with the study of chemical changes caused by the passage of an electric current and the production of electrical en- ergy by chemical reactions. In fact, the field of Electrochemistry encompasses a huge array of different phenomena (e.g., electrophoresis and corrosion), devices (elec- trochromic displays, electroanalytical sensors, batteries, and fuel cells), and technolo- gies (the electroplating of metals and the large-scale production of aluminum and chlorine). While the basic principles of Electrochemistry discussed in this text apply to all of these, the main emphasis here is on the application of electrochemical methods to the study of chemical systems. Scientists make electrochemical measurements on chemical systems for a variety of reasons. They may be interested in obtaining thermodynamic data about a reaction. They may want to generate an unstable intermediate such as a radical ion and study its rate of decay or its spectroscopic properties. They may seek to analyze a solution for trace amounts of metal ions or organic species. In these examples, electrochemical methods are employed as tools in the study of chemical systems in just the way that spectroscopic methods are frequently applied. There are also investigations in which the electrochemi- cal properties of the systems themselves are of primary interest, for example, in the design of a new power source or for the electrosynthesis of some product. Many electrochemical methods have been devised. Their application requires an understanding of the fundamen- tal principles of electrode reactions and the electrical properties of electrode–solution in- terfaces. In this chapter, the terms and concepts employed in describing electrode reactions are introduced.
eBook - PDFFuel Cells
Principles, Design, and Analysis
- Shripad T. Revankar, Pradip Majumdar(Authors)
- 2016(Publication Date)
- CRC Press(Publisher)
33 2 Review of Electrochemistry Electrochemistry is the study of mutual transformation of chemical and elec-trical energy. Specifically, it deals with chemical reactions driven by an electric current and with the electricity produced by chemical reactions. Examples of Electrochemistry are electroplating, iron oxidation (rusting), solar-energy conversion, electrochemical conversions (fuel cells, batteries), photosynthe-sis, and respiration. In this chapter, the principles of Electrochemistry are reviewed. First, let us briefly look into the history of Electrochemistry. The field of Electrochemistry was discovered near the beginning of the 19th century. In 1791, Italian physician and anatomist Luigi Galvani observed that while dissecting a frog, a coworker touched the internal cru-ral nerves of the frog with the tip of a scalpel and all the muscles of the frog’s limb contracted. This led him to establish a relation between chemical reactions and electricity. In 1880, Alessandro Volta reported on chemical-to-electrical energy conversion to the Royal Society in London. He showed that by placing a brine-soaked membrane in contact with silver and zinc plates, on either side, an electric current would flow in the external circuit connecting the silver and zinc plates. Volta is credited with building the first electrochemical cell, which consisted of two electrodes: one made of zinc, the other of copper and the electrolyte is sulfuric acid or a brine mixture of salt and water. Following this, the same year William Nicholson and Johann Wilhelm Ritter succeeded in decomposing water into hydrogen and oxy-gen by electrolysis (electricity to chemicals). Further work on electrolysis by Sir Humphry Davy led to the conclusion that the production of electricity in simple electrolytic cells resulted from chemical action and that chemi-cal combination occurred between substances of opposite charge.
- S Borenstein(Author)
- 1994(Publication Date)
- Woodhead Publishing(Publisher)
Chapter 4 Electrochemistry Electrochemistry is the science of chemical changes that accompany the passage of electric current. Piron defined Electrochemistry as a chemical science and technology, concerned with the properties of ions in solution and their reactions at metal-solution interfaces.' Electric conduction occurs through the motion of charged particles, of either electrons or ions. Current passes through an electrolyte and causes chemical reactions at the electrodes. A galvanic cell, or battery, is an example of a chemical reaction arranged to produce electrons. The reverse, using electricity to produce a chemical reaction, is termed electroplating, and is also an example of Electrochemistry. The electrochemical nature of corrosion offers a method of determining the corrosion rate. This chapter covers Electrochemistry's relationship with the corrosion of metals. It describes how microorganisms can influence electrochemical reactions and cor- rosion and how electrochemical methods may be used to investigate such processes. Electrochemistry can be discussed in terms of thermodynamics and kinetics. Thermodynamics will tell us what can happen, kinetics will tell us what will happen.2 Thermodynamics relates to the conversion of heat into energy, while kinetics relates to the study of reaction rates and the factors that affect those rates. 4.1 Glossary The following are frequently used terms in Electrochemistry and corrosion. 4.2.1 Corrosion-related terms 0 Corrosion: the deterioration of a substance (usually a metal) or its properties, due to a reaction with its environment. 0 A chemical reaction: a reaction that does not involve the transfer of electrons. An electrochemica1 reaction: a chemical reaction involving the transfer of electrons. 113 114 Microbiologically influenced corrosion handbook 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Electrode: a metal in contact with an electrolyte at the location where the current either enters or leaves the metal to enter the solution.
eBook - PDF- Ageetha Vanamudan(Author)
- 2023(Publication Date)
- Delve Publishing(Publisher)
258 14.18 Metallurgy ................................................................................... 259 14.19 Production of Chemicals.............................................................. 259 14.20 Investigations Into the Natural World ........................................... 260 Introduction to Molecular Science 238 In one of two ways, chemical reactions can absorb or release electricity as energy. Electrochemistry, a branch of chemistry that investigates the process, is concerned with the conversion of chemical and electrical energy. Electrochemistry has a wide range of practical applications in everyday life. Batteries, which are commonly used in flashlights, calculators, and vehicles, generate energy through chemical reactions (Shin et al., 2019). Electricity is used to apply metals such as gold and chromium to objects. Electrochemistry plays a significant role in the propagation of nerve impulses in biological systems. Redox chemistry, or the movement of electrons, underpins all electrochemical reactions. Within an electrochemical cell, electricity and chemical energy may be converted back and forth. The following are the three elements of an electrochemical reaction. Only in the presence of a solution that allows for redox reactions can they occur. Conducting these reactions in water facilitates electron and ion mobility. Electron transfer necessitates the use of a conductor. Electrons may go via this conductor, which is often a wire. The salt bridge must be capable of transferring ions through it as part of its function. 14.1 THE Electrochemistry TECHNIQUE The characteristics of the negatively charged electron impact the interactions between matter and electric current. Atoms, groups of molecules, and the like have a strong attraction to positively charged matter particles like protons. This affinity is similar to the chemical attraction between atoms.
eBook - PDF- Young, William Vining, Roberta Day, Beatrice Botch(Authors)
- 2017(Publication Date)
- Cengage Learning EMEA(Publisher)
AlbertSmirnov/iStockphoto.com 21 Electrochemistry Unit Outline 21.1 Oxidation–Reduction Reactions and Electrochemical Cells 21.2 Cell Potentials, Free Energy, and Equilibria 21.3 Electrolysis 21.4 Applications of Electrochemistry: Batteries and Corrosion In This Unit… Why aren’t there more electric cars? Why do we still use corded power tools instead of only using battery-powered tools? Why do the batteries in our portable electronic devices run down so quickly? The answer to all these questions lies in our ability to make good batteries. In this unit we explore the chemistry of batteries, where spontaneous reactions take place by the indirect transfer of electrons from one reactant to another. We will also investigate electrolysis, the process where we use external power supplies such as batteries to force nonspontaneous reactions to form products. Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300 Unit 21 Electrochemistry 666 21.1 Oxidation–Reduction Reactions and Electrochemical Cells 21.1a Overview of Oxidation–Reduction Reactions In Chemical Reactions and Solution Stoichiometry (Unit 9) we first encountered oxida-tion–reduction reactions in our study of chemical reactions. Electrochemistry is the area of chemistry that studies oxidation–reduction reactions, also called redox reactions, which involve electron transfer between two or more species. Recall that in a redox reaction, ● the species that loses electrons has been oxidized and is the reducing agent in the reaction, and ● the species that gains electrons has been reduced and is the oxidizing agent in the reaction. Oxidizing and reducing agents are identified in a chemical reaction by using the oxida-tion number (or oxidation state) of the species in the reaction. Recall that the oxidation number of an oxidized species increases during the reaction, whereas the oxidation num-ber of a reduced species decreases during the reaction.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
____________________ WORLD TECHNOLOGIES ____________________ Chapter 2 Electrochemistry English chemists John Daniell (left) and Michael Faraday (right), both credited as founders of Electrochemistry today. Electrochemistry is a branch of chemistry that studies chemical reactions which take place in a solution at the interface of an electron conductor (a metal or a semiconductor) and an ionic conductor (the electrolyte), and which involve electron transfer between the electrode and the electrolyte or species in solution. If a chemical reaction is driven by an external applied voltage, as in electrolysis, or if a voltage is created by a chemical reaction as in a battery, it is an electrochemical reaction. In contrast, chemical reactions where electrons are transferred between molecules are called oxidation/reduction (redox) reactions. In general, Electrochemistry deals with situations where oxidation and reduction reactions are separated in space or time, connected by an external electric circuit to understand each process. ____________________ WORLD TECHNOLOGIES ____________________ History 16th to 18th century developments German physicist Otto von Guericke beside his electrical generator while conducting an experiment. Understanding of electrical matters began in the sixteenth century. During this century the English scientist William Gilbert spent 17 years experimenting with magnetism and, to a lesser extent, electricity. For his work on magnets, Gilbert became known as the Father of Magnetism. He discovered various methods for producing and strengthening magnets. In 1663 the German physicist Otto von Guericke created the first electric generator, which produced static electricity by applying friction in the machine. The generator was made of a large sulfur ball cast inside a glass globe, mounted on a shaft. The ball was rotated by means of a crank and a static electric spark was produced when a pad was rubbed against the ball as it rotated.
eBook - PDF- D Pletcher, R Greff, R Peat, L M Peter, J Robinson(Authors)
- 2001(Publication Date)
- Woodhead Publishing(Publisher)
1 Introduction to the fundamental concepts of Electrochemistry This book was initially prepared as lecture notes for an Electrochemistry course which has been presented regularly in Southampton and elsewhere during the past fifteen years. The course seeks to develop an understanding of electro-chemical experiments and to illustrate the applications of electrochemical methods to, for example, the study of redox couples, homogeneous chemical reactions, and surface science. In many studies, several of the techniques will be equally applicable, but there are situations where one technique has a unique advantage and hence the course also seeks to discuss the selection of method and the design of experiments to aid the solution of both chemical and techno-logical problems. It will be shown that the methods are, in general, based on very similar principles. Commonly the need is to carry out an experiment so as to separate the effects on the measurements of the kinetics of electron transfer or a coupled chemical reaction from those which arise from mass transport of species to and from the electrode surface. Thus it is important to understand how the measure-ment of current as a function of time in potential step methods, of potential scan rate in cyclic voltammetry, of frequency in ac methods, or of rotation rate in experiments with a rotating disc electrode, can be used to isolate pure kinetic information. A grasp of the fundamentals of Electrochemistry and an under-standing of the theoretical background to the methods is extremly helpful to the experimental electrochemist for another reason - although often disguised by our use of the literature, e.g. of equations or dimensionless plots, the con-clusions from electrochemical experiments always come from a comparison of the experimental data with a theoretical response, derived from a mathematical description of the experiment and the solution of the resulting equations. Hence
eBook - PDF- Arthur Adamson(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
CHAPTER THIRTEEN ELECTROCHEMICAL CELLS The preceding chapter dealt primarily with the physical chemistry of electrolyte solutions; we now concern ourselves with the overall chemical process that occurs when electricity is passed through a conducting solution. The emphasis will be on the work associated with this overall change, as measured by the reversible cell potential. Since reversible work at constant temperature and pressure corre-sponds to a free energy change, we will thus be able to bring the emf of cells into the general scheme of thermodynamics. The chapter concludes with a discussion of irreversible electrode processes, that is, with the physical chemistry of the approach of ions to, and their reaction àt, the surface of an electrode. 13-1 Definitions and Fundamental Relationships A. Cell Conventions An electrochemical cell has, as essential features, a current-carrying solution and two electrodes at which oxidation and reduction processes occur, respectively, as current flows. Figure 13-1 gives a schematic example of a fairly typical cell for this chapter; we have hydrogen and silver-silver chloride electrodes dipping into an aqueous solution of HCl. The hydrogen electrode, incidentally, typically consists of a platinized platinum metal surface arranged so that hydrogen gas bubbles past as it dips partly into the solution, the object being to provide the most intimate possible gas-solution-metal contact. Platinized platinum is merely platinum metal on which additional, very finely divided platinum has been deposited electrolytically; the result is a high area, catalytically active surface. A silver-silver chloride electrode consists of silver on which a fine-grained, adherent deposit of silver chloride has been placed, again electrolytically.
eBook - PDFBatteries for Electric Vehicles
Materials and Electrochemistry
- Helena Berg(Author)
- 2015(Publication Date)
- Cambridge University Press(Publisher)
I Electrochemistry and battery technologies 1 The electrochemical cell The most fundamental unit of a battery is the electrochemical cell. All performance characteristics are dependent on the materials inside the cell, and all cells work according to some general principles independent of the materials employed. The purpose of this chapter is to bring together the fundamental aspects of an electrochemical cell as the basis for all further steps in the development of a battery intended for electric vehicles. An electrochemical cell converts chemical energy to electric energy when discharged, and vice versa. In addition, the electrochemical cells can be said to be either electrolytic or galvanic. In an electrolytic cell, the electric energy is converted to chemical energy (charging of the battery) and in a galvanic cell chemical energy is converted to electric energy (discharging of the battery). The basic design of an electrochemical cell consists of a positive and a negative electrode separated by an electrolyte, as shown in Figure 1.1. The chemical reactions taking place during charge and discharge processes are based on electrochemical oxidation and reduction reactions, known as the redox reactions, at the two electrodes. In these reactions, electrons are transferred via an external circuit from one electrode to another, and at the same time ions are transferred inside the cell, through the electrolyte, to maintain the charge balance. The species oxidised is called the oxidant, and the species reduced is called the reductant. The oxidation reaction takes place at the negative electrode, the anode, and electrons are transferred, via the external circuit, to the positive electrode, the cathode, where the reduction reaction takes place by accepting the electrons. The negative electrode is thus an electron donor, and the positive electrode an electron acceptor. During charge and discharge of a battery, the nomenclature of the electrodes changes.
eBook - PDF- Vladimir S. Bagotsky(Author)
- 2005(Publication Date)
- Wiley-Interscience(Publisher)
This was the starting point for the concepts of electrode potentials, which are a highly important compo- nent of modern Electrochemistry. On the other hand, a number of observations were made in the first half of the nineteenth century from which it was concluded that potential gradients exist even in living tissue. In fact, even Galvani, when repeating his experiments with identical metal pieces, had obtained the same effect as before; but his contemporaries had paid no attention to these studies. Thus, Galvani’s ideas were also vindicated, and it is from these ideas that bioElectrochemistry started. BioElectrochemistry is a science at the junction of many other sciences: electro- chemistry, biophysics, biochemistry, electrophysiology, and others. The biological systems are extremely diverse in their constitution and detailed mechanism of func- tioning; each system has its own specific morphological and physiological features. In contrast to electrophysiology, bioElectrochemistry is concerned only with the 573 Fundamentals of Electrochemistry, Second Edition, By V. S. Bagotsky Copyright © 2006 John Wiley & Sons, Inc. general and basic laws of the electrochemical processes occurring in biological enti- ties, and disregards the particular features of specific systems. For this reason, bio- electrochemical studies often are conducted not on natural objects but on synthetic model systems (e.g., artifical membranes). From an electrochemical viewpoint, biological systems are highly branched cir- cuits consisting of ionic conductors: of aqueous electrolyte solutions and highly selective membranes. These circuits lack metallic conductors, but it has been found relatively recently that they contain sections that behave like electronic conductors (i.e., sections in which electrons can be transferred over macroscopic distances, owing to a peculiar relay-type mechanism).
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