Electrochemistry spontaneous reaction

These early observations have evolved into the branch of chemistry called electrochemistry. This subject deals not only with the use of spontaneous chemical reactions to produce electricity but also with the use of electricity to drive non-spontaneous reactions forward. Electrochemistry also provides techniques for monitoring chemical reactions and measuring properties of solutions such as the pK, of an acid. Electrochemistry even allows us to monitor the activity of our brain and heart (perhaps while we are trying to master chemistry), the pH of our blood, and the presence of pollutants in our water supply. 

In this section, you learned about electrolytic cells, which convert electrical energy into chemical energy. You compared the spontaneous reactions in galvanic cells, which have positive cell potentials, with the non-spontaneous reactions in electrolytic cells, which have negative cell potentials. You then considered cells that act as both galvanic cells and electrolytic cells in some common rechargeable batteries. These batteries are an important application of electrochemistry. In the next two sections, you will learn about many more electrochemical applications. 

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. 

Well-known phenomena as corrosion of e.g. cobber roofs are closely related to the electrochemistry. Because corroded metal as e.g. iron looses its strength corrosion chemistiy has great practical importance. Metals are especially exposed to corrosion as metals are easily oxidised. From tables of standard reduction potentials one will see that with the exception of noble metals as e.g. gold the standard reduction potentials of common metals are lower than for oxygen. This means that the oxidation of most metals is a spontaneous reaction even though not metals are equally oxidised in the presence of oxygen. 

Corrosion phenomenon is a natural one that occurs in nature. Gibbs free energy orders it as a spontaneous reaction. Basically, it is the oxidation reaction part of an electrochemical one. This suggests that corrosion could be explained from the viewpoint of electrochemistry. 

In electrochemistry, spontaneous redox reactions are used for what purpose ... 

Only one equilibrium constant for gas-phase reactions (Chapter 12), the thermodynamic constant K, often referred to as Kp. This simplifies not only the treatment of gaseous equilibrium, but also the discussion of reaction spontaneity (Chapter 17) and electrochemistry (Chapter 18). 

There are two principal chemical concepts we will cover that are important for studying the natural environment. The first is thermodynamics, which describes whether a system is at equilibrium or if it can spontaneously change by undergoing chemical reaction. We review the main first principles and extend the discussion to electrochemistry. The second main concept is how fast chemical reactions take place if they start. This study of the rate of chemical change is called chemical kinetics. We examine selected natural systems in which the rate of change helps determine the state of the system. Finally, we briefly go over some natural examples where both thermodynamic and kinetic factors are important. This brief chapter cannot provide the depth of treatment found in a textbook fully devoted to these physical chemical subjects. Those who wish a more detailed discussion of these concepts might turn to one of the following texts Atkins (1994), Levine (1995), Alberty and Silbey (1997). 

To master one scientific topic after another, Haber skipped dinners and studied until 2 a.m. With overflowing enthusiasm, he ignored the conventional boundaries between abstract and practical science between chemistry, physics, and engineering and between mechanics, technicians, and scientists. He solved industrial problems posed by the iron plates used to print banknotes and by Karlsruhe s corroded water and gas mains, and then made fundamental discoveries in electrochemistry. Conversely, he used the abstract theory of gas reactions in flames to explain to manufacturers why some reactions continue spontaneously while others stop. Soon he had contributed basic scientific insights to almost every area of physical chemistry. 

If one takes a spontaneous electron-transfer reaction and separates the materials undergoing oxidation and reduction, allowing the electron transfer to occur through a good conductor such as a copper wire, a battery is created. By proper design, the electrical energy associated with reactions of this type can be harnessed. The fields of electrochemistry (e.g., batteries) and pyrotechnics (e.g., fireworks) are actually very close relatives. The reactions involved in the two areas can look strikingly similar ... 

In addition to the foregoing, it is customary to include under electrochemistry (I) processes for which the net reaction is physical transfer, e g., concentration cells (2) electrokinetic phenomena, e.g.. electrophoresis. eleclroosmnsis, and streaming potential (3) properties ot electrolytic solutions, if they are determined by electrochemical or other means, e g.. activity coefficients and hydrogen ion concentration (4) processes in which electrical energy is first converted to heal, which in turn causes a chemical reaction that would not occur spontaneously at ordinary temperature. The... 

Electrochemistry is the area of chemistry concerned with the interconversion of chemical and electrical energy. Chemical energy is converted to electrical energy in a galvanic cell, a device in which a spontaneous redox reaction is used to produce an electric current. Electrical energy is converted to chemical energy in an electrolytic cell, a cell in which an electric current drives a nonspontaneous reaction. It s convenient to separate cell reactions into half-reactions because oxidation and reduction occur at separate electrodes. The electrode at which oxidation occurs is called the anode, and the electrode at which reduction occurs is called the cathode. 

In Section 21.2, you learned that rechargeable batteries can regain their electrical potential and be reused. You learned that a current can be introduced to cause the reverse reaction, which is not spontaneous, to happen. This aspect of electrochemistry—the use of an external force, usually in the form of electricity, to drive a chemical reaction—is important and has many practical applications. 

Electrochemistry is best defined as the study of the interchange of chemical and electrical energy. It is primarily concerned with two processes that involve oxidation-reduction reactions the generation of an electric current from a spontaneous chemical reaction and the opposite process, the use of a current to produce chemical change. 

Oxidation-reduction reactions are the basis of the branch of chemistry called electrochemistry. Such a reaction may occur spontaneously and produce electrical energy, as in a galvanic cell. If the reaction does not occur spontaneously, the addition of electrical energy may initiate a chemical change, a process called electrolysis. 

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