Electrochemistry balancing oxidation-reduction

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. 

Balancing Oxidation-Reduction Reactions by the Half-Reaction Method 1 7.5 Electrochemistry An Introduction 1 7.6 Batteries 1 7.7 Corrosion 1 7.8 Electrolysis... 

You had a brief introduction to the topic of electrochemistry in Chapter 11 when you reviewed the oxidation-reduction process in which reactions occur by the transfer of electrons. One of the procedures you looked at was the half-reaction method of balancing redox equations. In this chapter, we will be looking at the oxidation and reduction process in even more depth. 

The loss of an electron by M, M + + e, is the process of oxidation in electrochemistry. The electron is then accepted by an electrode of well defined potential, so that the oxidation potential Eox is the free energy of the reaction, as was seen in Figure 4.1. Similarly the reduction potential Ered is the energy of the reduction reaction, e.g. N + e - N. By definition the molecule, which is oxidized, is the donor (M in this case), and the molecule, which is reduced, is the acceptor. The electron transfer from M to N is therefore equivalent to the combined oxidation of the donor and reduction of the acceptor, so that the energy balance is... 

ESI nebulization involves a variety of electrochemical processes at the needle and at the counter electrode [27, 30]. The ESI interface can be considered as a electrochemical cell, in which part of the ion transport takes place through the gas phase (Figure 6.1). In positive-ion mode, an emichment of positive electrolyte ions occurs at the solution meniscus as the result of an electrophoretic charge separation. The liquid meniscus is pulled into a cone which emits a fine mist of droplets with an excess positive charge. Charge balance is attained by electrochemical oxidation at the capillary tip and reduction at the counter electrode. The topic arose significant discussion in 2000 and the discussion partners continued to disagree on the role of electrochemistry inESI-MS [39]. 

The half-reaction method for balancing redox reactions divides the overall redox reaction into oxidation and reduction half-reactions. Each half-reaction is balanced for atoms and charge. Then, one or both are multiplied by some integer to make electrons gained equal electrons lost, and the half-reactions are recombined to give the balanced redox equation. The half-reaction method is commonly used for studying electrochemistry because... 

Of course, electrochemistry is only possible in a cell which contains both an anode and a cathode and, owing to the need to maintain an overall charge balance, the amount of reduction at the cathode and oxidation at the anode must be equal. The total chemical change in the cell is determined by adding the two individual electrode reactions thus the chemical change in a lead/acid battery is obtained by... 

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