Chapter 7 Electrochemistry §76 Reversible cell Outside class reading vine: pp. 417 14.4 Galvanic cells pp. 423 14.5 types of reversible electrodes
Chapter 7 Electrochemistry §7.6 Reversible cell Levine: pp. 417 14.4 Galvanic cells: pp. 423 14.5 types of reversible electrodes Outside class reading
§76 Reversible cell 7.6.1 Basic concepts of electrochemical apparatus (1) Electrochemical apparatus Anode 078 Cathode Electrolytic cell; u Galvanic/voltaic cell Components Electrodes: positive/negative electrolytic solution? Reaction: oxidation reaction anode anodic reaction reductive reaction: cathode cathodic reactions
Electrolytic cell; Galvanic/voltaic cell (1) Electrochemical apparatus Reaction: oxidation reaction: anode, anodic reaction reductive reaction: cathode, cathodic reactions. Components: Electrodes: positive/negative electrolytic solution? 7.6.1 Basic concepts of electrochemical apparatus §7.6 Reversible cell
§76 Reversible cell 7.6.1 Basic concepts of electrochemical apparatus (2)Components of an electrode 1. Current collector(first-type conductor 2. Active materials: involves in electrochemical reaction 3. Electrolytic solution(second-type conductor) Question: Point out the current collector, active materials and electrolytic solution of the following electrode. 1)Zn(s) Zn*(sIn 2)(Pt), H2(g, Pe)H*(sIn
(2) Components of an electrode: 1. Current collector (first-type conductor) 2. Active materials: involves in electrochemical reaction 3. Electrolytic solution (second-type conductor). Question: Point out the current collector, active materials and electrolytic solution of the following electrode. 1) Zn(s)|Zn2+ (sln.) 2) (Pt), H2 (g, p)|H+ (sln.) 7.6.1 Basic concepts of electrochemical apparatus §7.6 Reversible cell
§76 Reversible cell 7.6.2 Interfacial reaction-half reaction and electrode reaction Differences between chemical and electrochemical reactions (e 2Fe3++ sn2 2Fe2++ Sn4+ at electrode/solution interface Interfacial reaction Fee sn: @irel half-reactions S Sn4++2 Fe3 2Fe3++2e-)2Fe in bulk solution cathode anode Principle for cell design: To harvest useful energy, the oxidizing and reducing agent has to be separated physically in two different compartments so as to make the electron passing through an external circuit
Differences between chemical and electrochemical reactions 2Fe3+ + Sn2+ ⎯→ 2Fe2+ + Sn4+ half-reactions: Sn2+ ⎯→ Sn4+ + 2e− 2Fe3+ + 2e- ⎯→ 2Fe2+ at electrode / solution interface in bulk solution Interfacial reaction 7.6.2 Interfacial reaction—half reaction and electrode reaction Principle for cell design: To harvest useful energy, the oxidizing and reducing agent has to be separated physically in two different compartments so as to make the electron passing through an external circuit. §7.6 Reversible cell
§76 Reversible cell 7.6.3 Reversibility of electrochemical cell (1)Relationship between chemical energy Thermodynamic reversibility and electric energy dG=-SdT+vdp+sw 1. Reversible reaction The electrode At constant temperature and pressure reaction reverts when shift from charge △G=W to discharge Reversible process: conversion of chemical reversible electrode energy to electric energy in a thermo dynamic reversible manner or vice versa. 2. Reversible pre △G=W"'=gv=-mFE 1→0, no current flows. Maximum useful work The relation bridges thermodynamics and electrochemistry
Maximum useful work (1) Relationship between chemical energy and electric energy At constant temperature and pressure Reversible process: conversion of chemical energy to electric energy in a thermodynamic reversible manner or vice versa. The relation bridges thermodynamics and electrochemistry §7.6 Reversible cell 7.6.3 Reversibility of electrochemical cell 1. Reversible reaction: The electrode reaction reverts when shift from charge to discharge. reversible electrode 2. Reversible process: I → 0, no current flows. Thermodynamic reversibility §7.6 Reversible cell d d d ' G S T V p W = − + + = G W ' = = − G W QV nFE ' =