AmmeterBalls ofglasswool allowionstopassbutkeepKCI(conc)inU-tubeSaltbridgecontainingZn(s)Cu(s)EKCI(conc)anodecathodeS2e2eCu2Zn2+ZnCuZn(NO,)(aq)Cu(NO,)2(a)OxidationReductionZn(s)→ Zn2++2eCu2++2e-→Cu(s)agoftheHalf-cellHalf-cell
1-3-2Electrode Types and Cell Notation(1)Fourtypes of electrode:Metal-metalions electrodeElectrode reaction:Zn?++2e ZnElectrode notation: Zn (s) | Zn2+
1-3-2 Electrode Types and Cell Notation （1）Four types of electrode： l Metal- metal ions electrode Electrode reaction：Zn2+ + 2e Zn Electrode notation：Zn (s) Zn2+
Gas-ionelectrodeStandard hydrogen electrodeH(g, 1 atm) -Electrode reaction:2H++2e 台H,Electrode notation:PtPt/ H, (g) / H+H*(1 M)electrodeThe symbol (Pt) is used to indicate thepresence of an inert platinum cathode
l Gas-ion electrode Standard hydrogen electrode Electrode reaction： 2H+ + 2e H2 Electrode notation： Pt H2 (g)H+ The symbol (Pt) is used to indicate the presence of an inert platinum cathode
I Metal-insoluble metal salts electrode/ Metal-oxide-anionelectrode,eg. Calomel electrode and AgCl electrode are such kind ofelectrodes.Calomel electrode: On the surface of Hg, there is a layer ofHg,Cl,whichisin saturatedKCl solution.Electrodereaction:2Hg,Cl+2e←2Hg+2ClElectrode notation: Hg-Hg,Cl, (s) I ClAgClelectrodeElectrode reaction:AgCl+ e Ag + ClElectrode notation: Ag-AgCI (s) I CI
l Metal-insoluble metal salts electrode/ Metal-oxide-anion electrode, eg. Calomel electrode and AgCl electrode are such kind of electrodes. Calomel electrode：On the surface of Hg, there is a layer of Hg2Cl2 , which is in saturated KCl solution. Electrode reaction：2Hg2Cl2 + 2e 2Hg + 2ClElectrode notation：Hg- Hg2Cl2 (s) ClAgCl electrode Electrode reaction：AgCl + e Ag + ClElectrode notation：Ag-AgCl (s) Cl-
Redox electrode (ion-ion electrode)Electrode reaction:Fe3++eFe2+Electrode notation: PtFe3+, Fe2+
l Redox electrode（ion-ion electrode） Electrode reaction：Fe3+ + e Fe2+ Electrode notation：PtFe3+ , Fe2+