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Galvani potential

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where the difference on the left-hand side is the Galvani potential difference between the phases (1) and (2). Thus, the Galvani potential difference is determined entirely by the chemical difference of the two phases; specifically by the difference of the chemical potential of the charge carriers in
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The Galvani potential difference between an electrode and electrolyte (or between other two electrically conductive phases) forms in an analogous fashion, although the chemical potentials in the equation above may need to include all species involved in the electrochemical reaction at the interface.
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First, consider the Galvani potential between two metals. When two metals are electrically isolated from each other, an arbitrary voltage difference may exist between them. However, when two different metals are brought into electronic contact, electrons will flow from the metal with a lower voltage
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From the above equation, two metals in electronic contact (i.e., under electronic equilibrium) must have the same electrode potential. Also, the electrochemical potentials of the electrons within the two metals will be the same. However, their Galvani potentials will be different (unless the metals
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of the electrons in the bulk of both phases are equal. The actual numbers of electrons that passes between the two phases is small (it depends on the capacitance between the objects), and the occupancies of the electron bands are practically unaffected. Rather, this small increase or decrease in
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The Galvani potential difference is not directly measurable using voltmeters. The measured potential difference between two metal electrodes assembled into a cell does not equal the difference of the Galvani potentials of the two metals (or their combination with the solution Galvani potential)
901:{\displaystyle E^{(2)}-E^{(1)}=\left(\phi ^{(2)}-\phi ^{(S)}-{\frac {\mu _{j}^{(2)}}{z_{j}F}}\right)-\left(\phi ^{(1)}-\phi ^{(S)}-{\frac {\mu _{j}^{(1)}}{z_{j}F}}\right)=\left(\phi ^{(2)}-\phi ^{(1)}\right)-\left({\frac {\mu _{j}^{(2)}-\mu _{j}^{(1)}}{z_{j}F}}\right)} 498: 236: 1191: 1010:
which is effectively negative of the reduced electrochemical potential of electrons given in units of volts. It is noted that what one experimentally measures using an inert metallic probe and a voltmeter is
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Now, the electrochemical potential of a species is defined as a sum of its chemical potential and the local electrostatic potential:
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M is the additional metal (here assumed to be the metal (1)) that must be inserted into the circuit to close it,
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j denotes the species which are the carrier of electric current in the system (which are electrons in metals)
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The equality of the electrochemical potential between the two different phases in contact can be written as:
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Virkar, Anil V. (2010). "Mechanism of oxygen electrode delamination in solid oxide electrolyzer cells".
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because the cell needs to contain another metal-metal interface, as in the following schematic of a
1192:"The Course of Oxygen Partial Pressure and Electric Potentials across an Oxide Electrolyte Cell" 1203: 104: 66: 46: 23: 1014: 929: 8: 1045: 1207: 1227: 1145: 493:{\displaystyle \phi ^{(2)}-\phi ^{(1)}={\frac {\mu _{j}^{(1)}-\mu _{j}^{(2)}}{z_{j}F}}} 358: 1219: 1231: 1149: 1090: 1211: 1176: 1172: 1135: 1094: 1085: 1061: 367: 363:
z is the electrical charge carried by a single charge carrier (unity for electrons)
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in one phase. The corresponding potential differences computed between two phases.
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charge results in a shift in all the energy levels in the metals. An electrical
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V.S. Bagotsky, "Fundamentals of Electrochemistry", Willey Interscience, 2006.
1089:, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) " 518: 135: 1140: 1123: 1098: 231:{\displaystyle {\overline {\mu }}_{j}^{(1)}={\overline {\mu }}_{j}^{(2)}} 148: 128: 1215: 124: 120: 116: 1050: 112: 343:{\displaystyle {\overline {\mu }}_{j}=\mu _{j}+z_{j}F\phi } 1053:(interface between two immiscible electrolyte solutions) 546:
Instead, the measured cell potential can be written as:
141: 511: 1017: 963: 932: 555: 385: 290: 277:(1) and (2) denote phase 1 and phase 2, respectively. 250: 168: 69: 49: 26: 156:is formed at the interface between the two phases. 1023: 998: 938: 900: 492: 342: 263: 230: 75: 55: 32: 1190:Jacobsen, Torben; Mogensen, Mogens (2008-12-18). 999:{\displaystyle \pi =-{\frac {\mu _{e}}{F}}+\phi } 1243: 1189: 147:to the metal with the higher voltage until the 542:the vertical bar, |, denotes a phase boundary. 1117: 1115: 1139: 915:E is the potential of a single electrode, 1165:International Journal of Hydrogen Energy 1121: 15: 1112: 1244: 1162: 107:between two points in the bulk of two 918:(S) denotes the electrolyte solution. 533:M and M are the two different metals, 134:The Galvani potential is named after 142:Galvani potential between two metals 111:. These phases can be two different 512:Relation to measured cell potential 13: 1086:Compendium of Chemical Terminology 264:{\displaystyle {\overline {\mu }}} 14: 1268: 103:, Δφ, delta phi) is the electric 372:Φ is the electrostatic potential 271:is the electrochemical potential 1122:Trasatti, S. (1 January 1986). 1183: 1177:10.1016/j.ijhydene.2010.06.058 1156: 1103: 1074: 871: 865: 847: 841: 811: 805: 792: 786: 746: 740: 720: 714: 701: 695: 655: 649: 629: 623: 610: 604: 586: 580: 567: 561: 467: 461: 443: 437: 416: 410: 397: 391: 376:From the two equations above: 223: 217: 192: 186: 1: 1067: 1091:Galvani potential difference 1041:Absolute electrode potential 297: 256: 206: 175: 97:Galvani potential difference 7: 1034: 10: 1273: 1257:Electrochemical potentials 1128:Pure and Applied Chemistry 952:electromotive potential in 536:S denotes the electrolyte, 119:joined), or a solid and a 101:inner potential difference 1252:Electrochemical concepts 1141:10.1351/pac198658070955 1099:10.1351/goldbook.G02574 1025: 1000: 940: 902: 494: 344: 265: 232: 84: 77: 63:and surface potential 57: 34: 1026: 1001: 941: 903: 495: 345: 266: 233: 78: 76:{\displaystyle \chi } 58: 56:{\displaystyle \psi } 35: 33:{\displaystyle \phi } 19: 1024:{\displaystyle \pi } 1015: 961: 939:{\displaystyle \pi } 930: 926:Moreover, if define 553: 383: 288: 248: 166: 105:potential difference 67: 47: 24: 1208:2008ECSTr..13z.259J 1046:Electrode potential 875: 851: 750: 659: 471: 447: 227: 196: 1021: 996: 948:electric potential 936: 898: 855: 831: 730: 639: 490: 451: 427: 359:chemical potential 340: 261: 228: 200: 169: 85: 73: 53: 30: 20:Galvani potential 1216:10.1149/1.3050398 1171:(18): 9527–9543. 988: 892: 766: 675: 488: 300: 259: 209: 178: 93:Galvani potential 1264: 1236: 1235: 1196:ECS Transactions 1187: 1181: 1180: 1160: 1154: 1153: 1143: 1119: 1110: 1107: 1101: 1078: 1062:Donnan potential 1030: 1028: 1027: 1022: 1005: 1003: 1002: 997: 989: 984: 983: 974: 945: 943: 942: 937: 923:are identical). 907: 905: 904: 899: 897: 893: 891: 887: 886: 876: 874: 863: 850: 839: 829: 820: 816: 815: 814: 796: 795: 772: 768: 767: 765: 761: 760: 749: 738: 729: 724: 723: 705: 704: 681: 677: 676: 674: 670: 669: 658: 647: 638: 633: 632: 614: 613: 590: 589: 571: 570: 504:the two phases. 499: 497: 496: 491: 489: 487: 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163: 144: 123:(e.g., a metal 68: 65: 64: 48: 45: 44: 42:Volta potential 25: 22: 21: 12: 11: 5: 1270: 1260: 1259: 1254: 1238: 1237: 1182: 1155: 1134:(7): 955–966. 1111: 1102: 1072: 1071: 1069: 1066: 1065: 1064: 1059: 1054: 1048: 1043: 1036: 1033: 1020: 1008: 1007: 995: 992: 987: 982: 978: 972: 969: 966: 935: 920: 919: 916: 909: 908: 896: 890: 885: 881: 873: 870: 867: 862: 858: 854: 849: 846: 843: 838: 834: 827: 823: 819: 813: 810: 807: 803: 799: 794: 791: 788: 784: 779: 775: 771: 764: 759: 755: 748: 745: 742: 737: 733: 727: 722: 719: 716: 712: 708: 703: 700: 697: 693: 688: 684: 680: 673: 668: 664: 657: 654: 651: 646: 642: 636: 631: 628: 625: 621: 617: 612: 609: 606: 602: 597: 593: 588: 585: 582: 578: 574: 569: 566: 563: 559: 544: 543: 540: 537: 534: 527: 526: 513: 510: 501: 500: 486: 481: 477: 469: 466: 463: 458: 454: 450: 445: 442: 439: 434: 430: 423: 418: 415: 412: 408: 404: 399: 396: 393: 389: 374: 373: 370: 364: 361: 351: 350: 339: 336: 331: 327: 323: 318: 314: 310: 305: 299: 296: 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322:+ 317:j 309:= 304:j 224:) 221:2 218:( 213:j 198:= 193:) 190:1 187:( 182:j

Index


Volta potential
electrochemistry
potential difference
phases
solids
metals
liquid
electrode
electrolyte
Luigi Galvani
Fermi level
double layer
chemical potential
Faraday constant
galvanic cell
Absolute electrode potential
Electrode potential
ITIES
Volta potential
Donnan potential
IUPAC
Compendium of Chemical Terminology
Galvani potential difference
doi
10.1351/goldbook.G02574


"The absolute electrode potential: an explanatory note (Recommendations 1986)"
doi

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