मानक इलेक्ट्रोड विभव

साम्यावस्था में अर्ध सेलों (हाफ सेल) के एलेक्ट्रोड विभव को मानक इलेक्ट्रोड विभव (standard electrode potentials) कहते हैं। जब तत्वो को उनके मानक अपचयन विभव के आरोही क्रम मे व्यवस्थित करते हैं तो इस प्रकार प्राप्त हुइ श्रेणी विद्युत रासायनिक श्रेणी कहलाती है।

इनका उपयोग विद्युतरासायनिक सेल (electrochemical cell) (गैल्वानिक सेल) का विभव ज्ञात करने के लिये किया जा सकता है। इसके अलावा इनका उपयोग किसी विद्युतरासायनिक रिडॉक्स (redox) अभिक्रिया के साम्य की स्थिति का पता करने के लिये किया जा सकता है। अर्थात् इसकी सहायता से यह पता कर सकते हैं कि ऊष्मागतिकी की दृष्टि से किसी विद्युतरासायनिक अभिक्रिया की गति की दिशा क्या होगी।^{[1][2][3][4][5][6][7][8]}

नीचे की सूची में मानक एलेक्ट्रोड विभव वोल्ट में दिये हुए हैं। ये विभव मानक हाइड्रोजन एलेक्ट्रोड (standard hydrogen electrode) के सापेक्ष दिये हुए हैं।

सारणी में दर्शाये गये विभव के मान निम्नलिखित स्थितियों में सत्य होंगे-

• तापमान : 298.15 K (25 °C);
• the effective concentration of 1 mol/L for each aqueous species or a species in a mercury amalgam;
• the partial pressure of 101.325 kPa (absolute) (1 atm, 1.01325 bar) for each gaseous reagent. This pressure is used because most literature data are still given for this value rather than for the current standard of 100 kPa.
• the activity of unity for each pure solid, pure liquid, or for water (solvent).

प्रतीक : (s) – ठोस; (l) – द्रव; (g) – गैस; (aq) – जलीय (aqueous) (default for all charged species); (Hg) – अमलगम (amalgam)

अर्ध-अभिक्रिया	E° (V)	Ref.
&	-9
Zz	9
N ${\displaystyle {\tfrac {3}{2}}}$ N2(g) + H+ + e− ⇄ HN3(aq)	-3.09 −3.09	[5]
Li+ + e− ⇄ Li(s)	-3.0401 −3.0401	[4]
N2(g) + 4 H2O + 2 e− ⇄ 2 NH2OH(aq) + 2 OH−	-3.04 −3.04	[5]
Cs+ + e− ⇄ Cs(s)	-3.026 −3.026	[4]
Rb+ + e− ⇄ Rb(s)	-2.98 −2.98	[4]
K+ + e− ⇄ K(s)	-2.931 −2.931	[4]
Ba2+ + 2 e− ⇄ Ba(s)	-2.912 −2.912	[4]
La(OH)3(s) + 3 e− ⇄ La(s) + 3OH−	-2.90 −2.90	[4]
Sr2+ + 2 e− ⇄ Sr(s)	-2.899 −2.899	[4]
Ca2+ + 2 e− ⇄ Ca(s)	-2.868 −2.868	[4]
Eu2+ + 2 e− ⇄ Eu(s)	-2.812 −2.812	[4]
Ra2+ + 2 e− ⇄ Ra(s)	-2.8 −2.8	[4]
Na+ + e− ⇄ Na(s)	-2.71 −2.71	[4][8]
La3+ + 3 e− ⇄ La(s)	-2.379 −2.379	[4]
Y3+ + 3 e− ⇄ Y(s)	-2.372 −2.372	[4]
Mg2+ + 2 e− ⇄ Mg(s)	-2.372 −2.372	[4]
ZrO(OH)2(s) + H2O + 4 e− ⇄ Zr(s) + 4OH−	-2.36 −2.36	[4]
Al(OH)4− + 3 e− ⇄ Al(s) + 4 OH−	-2.33 −2.33
Al(OH)3(s) + 3 e− ⇄ Al(s) + 3OH−	-2.31 −2.31
H2(g) + 2 e− ⇄ 2 H−	-2.25 −2.25
Ac3+ + 3 e− ⇄ Ac(s)	-2.20 −2.20
Be2+ + 2 e− ⇄ Be(s)	-1.85 −1.85
U3+ + 3 e− ⇄ U(s)	-1.66 −1.66	[6]
Al3+ + 3 e− ⇄ Al(s)	-1.66 −1.66	[8]
Ti2+ + 2 e− ⇄ Ti(s)	-1.63 −1.63	[8]
ZrO2(s) + 4 H+ + 4 e− ⇄ Zr(s) + 2 H2O	-1.553 −1.553	[4]
Zr4+ + 4 e− ⇄ Zr(s)	-1.45 −1.45	[4]
TiO(s) + 2 H+ + 2 e− ⇄ Ti(s) + H2O	-1.31 −1.31
Ti2O3(s) + 2 H+ + 2 e− ⇄ 2 TiO(s) + H2O	-1.23 −1.23
Ti3+ + 3 e− ⇄ Ti(s)	-1.21 −1.21
Mn2+ + 2 e− ⇄ Mn(s)	-1.185 −1.185	[4]
Te(s) + 2 e− ⇄ Te2−	-1.143 −1.143	[2]
V2+ + 2 e− ⇄ V(s)	-1.13 −1.13	[2]
Nb3+ + 3 e− ⇄ Nb(s)	-1.099 −1.099
Sn(s) + 4 H+ + 4 e− ⇄ SnH4(g)	-1.07 −1.07
SiO2(s) + 4 H+ + 4 e− ⇄ Si(s) + 2 H2O	-0.91 −0.91
B(OH)3(aq) + 3 H+ + 3 e− ⇄ B(s) + 3 H2O	-0.89 −0.89
TiO2+ + 2 H+ + 4 e− ⇄ Ti(s) + H2O	-0.86 −0.86
Bi(s) + 3 H+ + 3 e− ⇄ BiH3	-0.8 −0.8
H2 H2O + 2 e− ⇄ H2(g) + 2 OH−	-0.8277 −0.8277	[4]
Zn2+ + 2 e− ⇄ Zn(Hg)	-0.7628 −0.7628	[4]
Zn2+ + 2 e− ⇄ Zn(s)	-0.7618 −0.7618	[4]
Ta2O5(s) + 10 H+ + 10 e− ⇄ 2 Ta(s) + 5 H2O	-0.75 −0.75
Cr3+ + 3 e− ⇄ Cr(s)	-0.74 −0.74
Au[Au(CN)2]− + e− ⇄ Au(s) + 2 CN−	-0.60 −0.60
Ta3+ + 3 e− ⇄ Ta(s)	-0.6 −0.6
PbO(s) + H2O + 2 e− ⇄ Pb(s) + 2 OH−	-0.58 −0.58
Ti2 TiO2(s) + 2 H+ + 2 e− ⇄ Ti2O3(s) + H2O	-0.56 −0.56
Ga3+ + 3 e− ⇄ Ga(s)	-0.53 −0.53
U4+ + e− ⇄ U3+	-0.52 −0.52	[6]
P H3PO2(aq) + H+ + e− ⇄ P(white[9]) + 2 H2O	-0.508 −0.508	[4]
P H3PO3(aq) + 2 H+ + 2 e− ⇄ H3PO2(aq) + H2O	-0.499 −0.499	[4]
P H3PO3(aq) + 3 H+ + 3 e− ⇄ P(red)[9] + 3H2O	-0.454 −0.454	[4]
Fe2+ + 2 e− ⇄ Fe(s)	-0.44 −0.44	[8]
C2 CO2(g) + 2 H+ + 2 e− ⇄ HOOCCOOH(aq)	-0.43 −0.43
Cr3+ + e− ⇄ Cr2+	-0.42 −0.42
Cd2+ + 2 e− ⇄ Cd(s)	-0.40 −0.40	[8]
GeO2(s) + 2 H+ + 2 e− ⇄ GeO(s) + H2O	-0.37 −0.37
Cu2O(s) + H2O + 2 e− ⇄ 2 Cu(s) + 2 OH−	-0.360 −0.360	[4]
PbSO4(s) + 2 e− ⇄ Pb(s) + SO42−	-0.3588 −0.3588	[4]
PbSO4(s) + 2 e− ⇄ Pb(Hg) + SO42−	-0.3505 −0.3505	[4]
Eu3+ + e− ⇄ Eu2+	-0.35 −0.35	[6]
In3+ + 3 e− ⇄ In(s)	-0.34 −0.34	[2]
Tl+ + e− ⇄ Tl(s)	-0.34 −0.34	[2]
Ge(s) + 4 H+ + 4 e− ⇄ GeH4(g)	-0.29 −0.29
Co2+ + 2 e− ⇄ Co(s)	-0.28 −0.28	[4]
P H3PO4(aq) + 2 H+ + 2 e− ⇄ H3PO3(aq) + H2O	-0.276 −0.276	[4]
V3+ + e− ⇄ V2+	-0.26 −0.26	[8]
Ni2+ + 2 e− ⇄ Ni(s)	-0.25 −0.25
As(s) + 3 H+ + 3 e− ⇄ AsH3(g)	-0.23 −0.23	[2]
MoO2(s) + 4 H+ + 4 e− ⇄ Mo(s) + 2 H2O	-0.15 −0.15
Si(s) + 4 H+ + 4 e− ⇄ SiH4(g)	-0.14 −0.14
Sn2+ + 2 e− ⇄ Sn(s)	-0.13 −0.13
O2(g) + H+ + e− ⇄ HO2•(aq)	-0.13 −0.13
Pb2+ + 2 e− ⇄ Pb(s)	-0.13 −0.13	[8]
WO2(s) + 4 H+ + 4 e− ⇄ W(s) + 2 H2O	-0.12 −0.12
P(red) + 3 H+ + 3 e− ⇄ PH3(g)	-0.111 −0.111	[4]
C CO2(g) + 2 H+ + 2 e− ⇄ HCOOH(aq)	-0.11 −0.11
Se(s) + 2 H+ + 2 e− ⇄ H2Se(g)	-0.11 −0.11
C CO2(g) + 2 H+ + 2 e− ⇄ CO(g) + H2O	-0.11 −0.11
SnO(s) + 2 H+ + 2 e− ⇄ Sn(s) + H2O	-0.10 −0.10
SnO2(s) + 2 H+ + 2 e− ⇄ SnO(s) + H2O	-0.09 −0.09
WO3(aq) + 6 H+ + 6 e− ⇄ W(s) + 3 H2O	-0.09 −0.09	[2]
P(white) + 3 H+ + 3 e− ⇄ PH3(g)	-0.063 −0.063	[4]
C HCOOH(aq) + 2 H+ + 2 e− ⇄ HCHO(aq) + H2O	-0.03 −0.03
H 2 H+ + 2 e− ⇄ H2(g)	0.0000	≡ 0
S4O62− + 2 e− ⇄ 2 S2O32−	+0.08
Fe3O4(s) + 8 H+ + 8 e− ⇄ 3 Fe(s) + 4 H2O	+0.085	[7]
N2(g) + 2 H2O + 6H+ + 6 e− ⇄ 2 NH4OH(aq)	+0.092
HgO(s) + H2O + 2 e− ⇄ Hg(l) + 2 OH−	+0.0977
Cu(NH3)42+ + e− ⇄ Cu(NH3)2+ + 2 NH3	+0.10	[2]
Ru(NH3)63+ + e− ⇄ Ru(NH3)62+	+0.10	[6]
N2H4(aq) + 4 H2O + 2 e− ⇄ 2 NH4+ + 4 OH−	+0.11	[5]
Mo H2MoO4(aq) + 6 H+ + 6 e− ⇄ Mo(s) + 4 H2O	+0.11
Ge4+ + 4 e− ⇄ Ge(s)	+0.12
C(s) + 4 H+ + 4 e− ⇄ CH4(g)	+0.13	[2]
C HCHO(aq) + 2 H+ + 2 e− ⇄ CH3OH(aq)	+0.13
S(s) + 2 H+ + 2 e− ⇄ H2S(g)	+0.14
Sn4+ + 2 e− ⇄ Sn2+	+0.15
Cu2+ + e− ⇄ Cu+	+0.159	[2]
S HSO4− + 3 H+ + 2 e− ⇄ SO2(aq) + 2 H2O	+0.16
UO22+ + e− ⇄ UO2+	+0.163	[6]
S SO42− + 4 H+ + 2 e− ⇄ SO2(aq) + 2 H2O	+0.17
TiO2+ + 2 H+ + e− ⇄ Ti3+ + H2O	+0.19
Bi3+ + 2e− ⇄ Bi+	+0.2
SbO+ + 2 H+ + 3 e− ⇄ Sb(s) + H2O	+0.20
As H3AsO3(aq) + 3 H+ + 3 e− ⇄ As(s) + 3 H2O	+0.24
GeO(s) + 2 H+ + 2 e− ⇄ Ge(s) + H2O	+0.26
UO2+ + 4 H+ + e− ⇄ U4+ + 2 H2O	+0.273	[6]
Re3+ + 3 e− ⇄ Re(s)	+0.300
Bi3+ + 3 e− ⇄ Bi(s)	+0.32
VO2+ + 2 H+ + e− ⇄ V3+ + H2O	+0.34
Cu2+ + 2 e− ⇄ Cu(s)	+0.340	[2]
Fe [Fe(CN)6]3− + e− ⇄ [Fe(CN)6]4−	+0.36
O2(g) + 2 H2O + 4 e− ⇄ 4 OH−(aq)	+0.40	[8]
Mo H2MoO4 + 6 H+ + 3 e− ⇄ Mo3+ + 2 H2O	+0.43
Bi+ + e− ⇄ Bi(s)	+0.50
C CH3OH(aq) + 2 H+ + 2 e− ⇄ CH4(g) + H2O	+0.50
S SO2(aq) + 4 H+ + 4 e− ⇄ S(s) + 2 H2O	+0.50
βNiOOH(s) + H2O + e− ⇄ βNi(OH)2(s) + OH− (Alkaline batteries: Ni-Cd, Ni-MH, Ni-Zn...)	+0.520	[10].
Cu+ + e− ⇄ Cu(s)	+0.520	[2]
C CO(g) + 2 H+ + 2 e− ⇄ C(s) + H2O	+0.52
I2(s) + 2 e− ⇄ 2 I−	+0.54	[8]
I3− + 2 e− ⇄ 3 I−	+0.53	[8]
Au [AuI4]− + 3 e− ⇄ Au(s) + 4 I−	+0.56
As H3AsO4(aq) + 2 H+ + 2 e− ⇄ H3AsO3(aq) + H2O	+0.56
Au [AuI2]− + e− ⇄ Au(s) + 2 I−	+0.58
MnO4− + 2 H2O + 3 e− ⇄ MnO2(s) + 4 OH−	+0.59
S2O32 − + 6 H+ + 4 e− ⇄ 2 S(s) + 3 H2O	+0.60
Mo H2MoO4(aq) + 2 H+ + 2 e− ⇄ MoO2(s) + 2 H2O	+0.65
O2(g) + 2 H+ + 2 e− ⇄ H2O2(aq)	+0.70
Tl3+ + 3 e− ⇄ Tl(s)	+0.72
PtCl62− + 2 e− ⇄ PtCl42− + 2 Cl−	+0.726	[6]
Se H2SeO3(aq) + 4 H+ + 4 e− ⇄ Se(s) + 3 H2O	+0.74
PtCl42− + 2 e− ⇄ Pt(s) + 4 Cl−	+0.758	[6]
Fe3+ + e− ⇄ Fe2+	+0.77
Ag+ + e− ⇄ Ag(s)	+0.7996	[4]
Hg22+ + 2 e− ⇄ 2 Hg(l)	+0.80
N NO3−(aq) + 2 H+ + e− ⇄ NO2(g) + H2O	+0.80
Au [AuBr4]− + 3 e− ⇄ Au(s) + 4 Br−	+0.85
Hg2+ + 2 e− ⇄ Hg(l)	+0.85
MnO4− + H+ + e− ⇄ HMnO4−	+0.90
Hg 2 Hg2+ + 2 e− ⇄ Hg22+	+0.91	[2]
Pd2+ + 2 e− ⇄ Pd(s)	+0.915	[6]
Au [AuCl4]− + 3 e− ⇄ Au(s) + 4 Cl−	+0.93
MnO2(s) + 4 H+ + e− ⇄ Mn3+ + 2 H2O	+0.95
Au [AuBr2]− + e− ⇄ Au(s) + 2 Br−	+0.96
Br2(l) + 2 e− ⇄ 2 Br−	+1.066	[4]
Br2(aq) + 2 e− ⇄ 2 Br−	+1.0873	[4]
I IO3− + 5 H+ + 4 e− ⇄ HIO(aq) + 2 H2O	+1.13
Au [AuCl2]− + e− ⇄ Au(s) + 2 Cl−	+1.15
Se HSeO4− + 3 H+ + 2 e− ⇄ H2SeO3(aq) + H2O	+1.15
Ag2O(s) + 2 H+ + 2 e− ⇄ 2 Ag(s) + H2O	+1.17
ClO3− + 2 H+ + e− ⇄ ClO2(g) + H2O	+1.18
Pt2+ + 2 e− ⇄ Pt(s)	+1.188	[6]
ClO2(g) + H+ + e− ⇄ HClO2(aq)	+1.19
I 2 IO3− + 12 H+ + 10 e− ⇄ I2(s) + 6 H2O	+1.20
ClO4− + 2 H+ + 2 e− ⇄ ClO3− + H2O	+1.20
O2(g) + 4 H+ + 4 e− ⇄ 2 H2O	+1.23	[8]
MnO2(s) + 4 H+ + 2 e− ⇄ Mn2+ + 2H2O	+1.23
Tl3+ + 2 e− ⇄ Tl+	+1.25
Cl2(g) + 2 e− ⇄ 2 Cl−	+1.36	[8]
Cr2O7− − + 14 H+ + 6 e− ⇄ 2 Cr3+ + 7 H2O	+1.33
CoO2(s) + 4 H+ + e− ⇄ Co3+ + 2 H2O	+1.42
N 2 NH3OH+ + H+ + 2 e− ⇄ N2H5+ + 2 H2O	+1.42	[5]
I 2 HIO(aq) + 2 H+ + 2 e− ⇄ I2(s) + 2 H2O	+1.44
Ce4+ + e− ⇄ Ce3+	+1.44
BrO3− + 5 H+ + 4 e− ⇄ HBrO(aq) + 2 H2O	+1.45
PbO β-PbO2(s) + 4 H+ + 2 e− ⇄ Pb2+ + 2 H2O	+1.460	[2]
PbO α-PbO2(s) + 4 H+ + 2 e− ⇄ Pb2+ + 2 H2O	+1.468	[2]
Br 2 BrO3− + 12 H+ + 10 e− ⇄ Br2(l) + 6 H2O	+1.48
Cl 2ClO3− + 12 H+ + 10 e− ⇄ Cl2(g) + 6 H2O	+1.49
MnO4− + 8 H+ + 5 e− ⇄ Mn2+ + 4 H2O	+1.51
O HO2• + H+ + e− ⇄ H2O2(aq)	+1.51
Au3+ + 3 e− ⇄ Au(s)	+1.52
NiO2(s) + 4 H+ + 2 e− ⇄ Ni2+ + 2 OH−	+1.59
Cl 2 HClO(aq) + 2 H+ + 2 e− ⇄ Cl2(g) + 2 H2O	+1.63
Ag2O3(s) + 6 H+ + 4 e− ⇄ 2 Ag+ + 3 H2O	+1.67
Cl HClO2(aq) + 2 H+ + 2 e− ⇄ HClO(aq) + H2O	+1.67
Pb4+ + 2 e− ⇄ Pb2+	+1.69	[2]
MnO4− + 4 H+ + 3 e− ⇄ MnO2(s) + 2 H2O	+1.70
O H2O2(aq) + 2 H+ + 2 e− ⇄ 2 H2O	+1.78
AgO(s) + 2 H+ + e− ⇄ Ag+ + H2O	+1.77
Co3+ + e− ⇄ Co2+	+1.82
Au+ + e− ⇄ Au(s)	+1.83	[2]
BrO4− + 2 H+ + 2 e− ⇄ BrO3− + H2O	+1.85
Ag2+ + e− ⇄ Ag+	+1.98	[2]
S2O82− + 2 e− ⇄ 2 SO42−	+2.010	[4]
O3(g) + 2 H+ + 2 e− ⇄ O2(g) + H2O	+2.075	[6]
Mn HMnO4− + 3 H+ + 2 e− ⇄ MnO2(s) + 2 H2O	+2.09
F2(g) + 2 e− ⇄ 2 F−	+2.87	[2][8]
F2(g) + 2 H+ + 2 e− ⇄ 2 HF(aq)	+3.05	[2]