Chapter 18
Electrochemistry
By Boundless
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A voltaic cell is a device that produces an electric current from energy released by a spontaneous redox reaction in two half-cells.
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Electrolysis uses electrical energy to induce a chemical reaction, which then takes place in an electrolytic cell.
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Cell notation is shorthand that expresses a certain reaction in an electrochemical cell.
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Standard reduction potentials provide a systematic measurement for different molecules' tendency to be reduced.
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The direction of a redox reaction depends on the relative strengths of the oxidants and reductants in a solution.
A metal is soluble in acid if it displaces H2 from solution, which is determined by the metal's standard reduction potential.
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The thermodynamics of redox reactions can be determined using their standard reduction potentials and the Nernst equation.
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In electrochemistry, the Nernst equation can be used to determine the reduction potential of an electrochemical cell.
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Walther Nernst proposed a mathematical model to determine the effect of reactant concentration on the electrochemical cell potential.
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In a galvanic cell, where a spontaneous redox reaction drives the cell to produce an electric potential, the change in Gibbs free energy must be negative.
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The equilibrium constant K can be calculated using the Nernst equation.
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A dry-cell battery uses an immobilized electrolyte that minimizes moisture and allows for superior portability.
Mercury batteries were a common electrochemical battery that were phased out of mainstream use in the U.S. by the 1996 Battery Act.
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Lead-acid batteries provide high currents and store charge for long periods of time, making them essential for vehicles.
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The demand for many varieties of rechargeable batteries is due to their lower cost and lower environmental impact.
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Lithium-ion batteries are rechargeable batteries commonly used in consumer electronics; they rely on Li+ migration.
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Fuel cells are a compelling alternative to batteries, but they are still in the early stages of development.
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Electrolysis is a way of separating a compound by passing an electric current through it; the products are the compound's component ions.
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Two commonly used methods of electrolysis involve molten sodium chloride and aqueous sodium chloride, which give different products.
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Pure water cannot undergo significant electrolysis without an electrolyte, such as an acid or a base.
The amount of chemical change that occurs in electrolysis is stoichiometrically related to the amount of electrons that pass through the cell.