7.2 Electrochemical cells -7.2.1 The construction of an electro- chemical cell 7.2.2 Electrolysis cells and the Faraday's law -7.2.3 The measurement of the electro- motive force of the cell 7.2.4 The maximum amount of electrical work and the Gibbs function
§ 7.2 Electrochemical cells 7.2.1 The construction of an electrochemical cell * 7.2.2 Electrolysis cells and the Faraday’s law 7.2.3 The measurement of the electromotive force of the cell 7.2.4 The maximum amount of electrical work and the Gibbs function
7.2.1 The construction of an electro- chemical cell The construction of Cu-Zn electrochemical cell: Electrons flow from Zn electrode to Cu electrode Salt bridge: agar KCI Zn/ZnSO solt. Cu/CuSO,solution ampere meter
7.2.1 The construction of an electrochemical cell The construction of Cu-Zn electrochemical cell: Electrons flow from Zn electrode to Cu electrode Cu/CuSO4 solution Zn/ ZnSO4 solt. ampere meter Salt bridge: agar + KCl
1.Galvanic (voltaic)cell anode:electrode at (原电池) which oxidation occurs 阳极：发生氧化反应的电极（亿） cathode:electrode at which reduction occurs 阴极：发生还原反应的电极(Cu) nagative electrode: ZnSO CuSO leasing electrons 负极：原电池中给出电子的电 极（因电子带负电），电势低 ampere meter positive electrode: Negative electrode Positive electrode (anode) (cathode) accepting electrons Zn/ZnSOsolt. Cu/CuSOsolt. 正极：原电池中接受电子的 电极（它吸引带负电的电子）， m然ca Cu-Zn cell 电势高
Cu-Zn cell 1. Galvanic (voltaic) cell （原电池） Positive electrode （cathode ） Cu/CuSO 4solt. Negative electrode (anode ） Zn/ ZnSO4 solt. 负极：原电池中给出电子的电 极 (因电子带负电 )，电势低 阴极：发生还原反应的电极(Cu) 正极：原电池中接受电子的 电极 (它吸引带负电的电子), 电势高 anode ：electrode at which oxidation occurs 阳极：发生氧化反应的电极 (Zn) cathode: electrode at which reduction occurs nagative electrode: leasing electrons positive electrode : accepting electrons ampere meter Zn ZnSO 4 Cu CuSO 4
In the voltaic cell: (releasing clectrons )Zn(s)-2e -Zn2*(ag) Oxidation negative electrode;anode reaction (accepting electrons)Cu2*(aq)+2e -Cu(s) Reduction reaction positive electrode;cathode Cell reaction: Zn(s)+Cu2*(aq)-Zn2*(aq)+Cu(s) Oxidized form +Ze-Reduced form Electronic couple:Zn2+/Zn,Cu2+/Cu Conducting metals,such as Cu.Zn Electrode Chemically inert conductor,such as Pt、graphite
Electronic couple：Zn /Zn ，Cu /Cu 2 + 2 + Conducting metals, such as Cu、Zn Chemically inert conductor, such as Pt、graphite Electrode (releasing electrons ) ：Zn(s) 2e Zn (aq) 2 − − + Oxidation reaction (accepting electrons) ：Cu (aq) 2e Cu(s) 2 + + − Reduction reaction Cell reaction： Zn(s) Cu (aq) Zn (aq) Cu(s) 2 2 + + + + Oxidized form e Reduced form − + Z In the voltaic cell: negative electrode; anode positive electrode; cathode
Cell diagram: ()Zn Zn2*(1.0molL)Cu2(1.0molL)Cu (+ The rules for writing the cell diagram: DBy convention,the negative electrode is written to the left side and the positive electrode appears to the right side.The salt bridge is denoted by the double vertical lines“l‖”if it is present.. 2A phase boundary between a solid electrode and the solution in a half cell is indicated by a single line"".The various species in the same phase are separated by a comma",".A solution or a gas should be given clear indication of its cB or pB
The rules for writing the cell diagram ： ①By convention, the negative electrode is written to the left side and the positive electrode appears to the right side. The salt bridge is denoted by the double vertical lines “ ‖ ” if it is present. Cell diagram ： ②A phase boundary between a solid electrode and the solution in a half cell is indicated by a single line “︱”. The various species in the same phase are separated by a comma “,” . A solution or a gas should be given clear indication of its c B or p B