Chapter 18: Electrochemistry: Galvanic Cells, Potentials, and Electrolysis

The foundation rests on oxidation-reduction reactions, where electron transfer drives the conversion of chemical energy into usable electrical current. Galvanic cells, also known as voltaic cells, represent spontaneous redox systems that generate electricity through controlled electron flow from the anode to the cathode via an external circuit, while ions migrate through an internal salt bridge to maintain charge balance. Students learn to represent these systems using standard cell notation and to identify the roles of each component. The chapter introduces standard reduction potentials, tabulated values that quantify the tendency of a species to accept electrons under reference conditions. By comparing reduction potentials of half-reactions, students calculate the overall cell potential and determine spontaneity using the fundamental relationship linking Gibbs free energy, the number of electrons transferred, Faraday's constant, and cell potential. The Nernst equation extends these calculations to non-standard conditions by accounting for concentration gradients and temperature effects on cell potential. The text then examines practical electrochemical systems including primary batteries like alkaline cells that provide single-use discharge, secondary batteries such as lead-acid and lithium-ion cells that can be recharged by reversing the internal redox reaction, and fuel cells that sustain electrical generation through continuous chemical supply. A dedicated section addresses corrosion, an electrochemical degradation process where metals lose electrons and deteriorate, using iron rusting as the primary example and exploring protection strategies including galvanization and sacrificial anode placement. The final major topic covers electrolysis, the non-spontaneous process where external electrical energy drives unfavorable redox reactions forward. Students apply Faraday's laws to relate electrical charge to moles of electrons and subsequently to quantities of reactants consumed and products formed, with emphasis on industrial processes such as aluminum extraction and chlorine generation. Together, these topics demonstrate how electrochemistry bridges chemical thermodynamics and practical technology in batteries, corrosion management, and industrial synthesis.