Deret elektrokimia

Deret elektrokimia atau deret Volta adalah urutan logam-logam (ditambah hidrogen) berdasarkan kenaikan potensial elektrode standarnya.
Umumnya deret volta yang sering dipakai adalah adalah:
Li K Ba Sr Ca Na Mg Al Mn Zn Cr Fe Cd Co Ni Sn Pb H Cu Hg Ag Pt Au
Pada Deret Volta, unsur logam dengan potensial elektrode lebih negatif ditempatkan di bagian kiri, sedangkan unsur dengan potensial elektrode yang lebih positif ditempatkan di bagian kanan.
Semakin ke kiri kedudukan suatu logam dalam deret tersebut, maka
Logam semakin reaktif (semakin mudah melepas elektron)
Logam merupakan reduktor yang semakin kuat (semakin mudah mengalami oksidasi)
Sebaliknya, semakin ke kanan kedudukan suatu logam dalam deret tersebut, maka
Logam semakin kurang reaktif (semakin sulit melepas elektron)
Logam merupakan oksidator yang semakin kuat (semakin mudah mengalami reduksi)
Salah satu metode untuk mencegah korosi antara lain dengan menghubungkan logam (misalnya besi) dengan logam yang letaknya lebih kiri dari logam tersebut dalam deret volta (misalnya magnesium) sehingga logam yang mempunyai potensial elektrode yang lebih negatif lah yang akan mengalami oksidasi. Metode pencegahan karat seperti ini disebut perlindungan katodik. Contoh lain dari perlindungan katodik adalah pipa besi, tiang telepon, dan berbagai barang lain yang dilapisi dengan zink, atau disebut Galvanisasi. Zink dapat melindungi besi dari korosi sekalipun lapisannya tidak utuh. Oleh karena potensial reduksi besi lebih positif daripada zink (posisinya dalam deret Volta lebih ke kanan), maka besi yang kontak dengan zink akan membentuk sel elektrokimia dengan besi sebagai katode. Dengan demikian besi terlindungi dan zink yang mengalami oksidasi. Badan mobil-mobil baru pada umumnya telah digalvanisasi, sehingga tahan karat.
Larutan garam suatu logam yang berada di bagian kiri dapat bereaksi dengan logam yang berada di bagian kanan. Contohnya larutan FeCl3 (feri chloride) boleh mengikis Cu (copper / tembaga).
Berikut adalah deret elektrokimia lengkap, diukur pada 298,15 K (25 °C):
| Setengah reaksi | E° (V) | Ref>  |
| --- | --- | --- |
| & | -9 |  |
| Zz | 9 |  |
| N3⁄2 N2(g) +  H+ +   e−  HN3(aq) |  -3.09 −3.09 |  |
| Li+ +  e−  Li(s) |  -3.0401 −3.0401 |  |
| N2(g) + 4 H2O +  2 e−  2 NH2OH(aq) + 2 OH− |  -3.04 −3.04 |  |
| Cs+ +  e−  Cs(s) |  -3.026 −3.026 |  |
| Rb+ +  e−  Rb(s) |  -2.98 −2.98 |  |
| K+ +  e−  K(s) |  -2.931 −2.931 |  |
| Ba2+ + 2 e−  Ba(s) |  -2.912 −2.912 |  |
| La(OH)3(s) + 3 e−  La(s) + 3 OH− |  -2.90 −2.90 |  |
| Sr2+ + 2 e−  Sr(s) |  -2.899 −2.899 |  |
| Ca2+ + 2 e−  Ca(s) |  -2.868 −2.868 |  |
| Eu2+ + 2 e−  Eu(s) |  -2.812 −2.812 |  |
| Ra2+ + 2 e−  Ra(s) |  -2.8 −2.8 |  |
| Na+ +  e−  Na(s) |  -2.71 −2.71 |  |
| La3+ + 3 e−  La(s) |  -2.379 −2.379 |  |
| Y3+ + 3 e−  Y(s) |  -2.372 −2.372 |  |
| Mg2+ + 2 e−  Mg(s) |  -2.372 −2.372 |  |
| ZrO(OH)2(s) +  H2O + 4 e−  Zr(s) + 4 OH− |  -2.36 −2.36 |  |
| Al(OH)4− + 3 e−  Al(s) + 4 OH− |  -2.33 −2.33 |  |
| Al(OH)3(s) + 3 e−  Al(s) + 3 OH− |  -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 |  |
| Al3+ + 3 e−  Al(s) |  -1.66 −1.66 |  |
| Ti2+ + 2 e−  Ti(s) |  -1.63 −1.63 |  |
| ZrO2(s) + 4 H+ + 4 e−  Zr(s) + 2 H2O |  -1.553 −1.553 |  |
| Zr4+ + 4 e−  Zr(s) |  -1.45 −1.45 |  |
| Ti3+ + 3 e−  Ti(s) |  -1.37 −1.37 |  |
| 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 |  |
| Zn(OH)42− + 2 e−  Zn(s) + 4 OH− |  -1.199 −1.199 |  |
| Mn2+ + 2 e−  Mn(s) |  -1.185 −1.185 |  |
| Fe(CN)64− + 6 H+ + 2  e−  Fe(s) + 4HCN(aq) |  -1.16 −1.16 |  |
| Te(s) + 2 e−  Te2− |  -1.143 −1.143 |  |
| V2+ + 2 e−  V(s) |  -1.13 −1.13 |  |
| 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 |  |
| Fe(OH)2(s) + 2 e−  Fe(s) + 2 OH− |  -0.89 −0.89 |  |
| Fe2O3(s) + 3 H2O + 2 e−  2Fe(OH)2(s) + 2 OH− |  -0.86 −0.86 |  |
| TiO2+ + 2 H+ + 4 e−  Ti(s) +  H2O |  -0.86 −0.86 |  |
| H2  H2O + 2 e−  H2(g) + 2 OH− |  -0.8277 −0.8277 |  |
| Bi(s) + 3 H+ + 3 e−  BiH3 |  -0.8 −0.8 |  |
| Zn2+ + 2 e−  Zn(Hg) |  -0.7628 −0.7628 |  |
| Zn2+ + 2 e−  Zn(s) |  -0.7618 −0.7618 |  |
| 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 |  |
| P H3PO2(aq) +  H+ +  e−  P(white) + 2 H2O |  -0.508 −0.508 |  |
| P H3PO3(aq) + 2 H+ + 2 e−  H3PO2(aq) +  H2O |  -0.499 −0.499 |  |
| P H3PO3(aq) + 3 H+ + 3 e−  P(red) + 3 H2O |  -0.454 −0.454 |  |
| Fe2+ + 2 e−  Fe(s) |  -0.44 −0.44 |  |
| 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 |  |
| 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 |  |
| PbSO4(s) + 2 e−  Pb(s) + SO42− |  -0.3588 −0.3588 |  |
| PbSO4(s) + 2 e−  Pb(Hg) + SO42− |  -0.3505 −0.3505 |  |
| Eu3+ +  e−  Eu2+ |  -0.35 −0.35 |  |
| In3+ + 3 e−  In(s) |  -0.34 −0.34 |  |
| Tl+ +  e−  Tl(s) |  -0.34 −0.34 |  |
| Ge(s) + 4 H+ + 4 e−  GeH4(g) |  -0.29 −0.29 |  |
| Co2+ + 2 e−  Co(s) |  -0.28 −0.28 |  |
| P H3PO4(aq) + 2 H+ + 2 e−  H3PO3(aq) +  H2O |  -0.276 −0.276 |  |
| V3+ +  e−  V2+ |  -0.26 −0.26 |  |
| Ni2+ + 2 e−  Ni(s) |  -0.25 −0.25 |  |
| As(s) + 3 H+ + 3 e−  AsH3(g) |  -0.23 −0.23 |  |
| AgI(s) +  e−  Ag(s) + I− |  -0.15224 −0.15224 |  |
| 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 |  |
| 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 |  |
| 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 |  |
| P(white) + 3 H+ + 3 e−  PH3(g) |  -0.063 −0.063 |  |
| Fe3+ + 3 e−  Fe(s) |  -0.04 −0.04 |  |
| C HCOOH(aq) + 2 H+ + 2 e−  HCHO(aq) +  H2O |  -0.03 −0.03 |  |
| H 2 H+ + 2 e−  H2(g) |    0.0000 | ≡ 0 |
| AgBr(s) +  e−  Ag(s) + Br− |  +0.07133 |  |
| S4O62− + 2 e−  2 S2O32− |  +0.08 |  |
| Fe3O4(s) + 8 H+ + 8 e−  3 Fe(s) + 4 H2O |  +0.085 |  |
| N2(g) + 2 H2O + 6 H+ + 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 |  |
| Ru(NH3)63+ +  e−  Ru(NH3)62+ |  +0.10 |  |
| N2H4(aq) + 4 H2O + 2 e−  2 NH4+ + 4 OH− |  +0.11 |  |
| 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 |  |
| 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 |  |
| S HSO4− + 3 H+ + 2 e−  SO2(aq) + 2 H2O |  +0.16 |  |
| UO22+ +  e−  UO2+ |  +0.163 |  |
| S SO42− + 4 H+ + 2 e−  SO2(aq) + 2 H2O |  +0.17 |  |
| TiO2+ + 2 H+ +  e−  Ti3+ +  H2O |  +0.19 |  |
| SbO+ + 2 H+ + 3 e−  Sb(s) +  H2O |  +0.20 |  |
| AgCl(s) +  e−  Ag(s) + Cl− |  +0.22233 |  |
| 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 |  |
| Re3+ + 3 e−  Re(s) |  +0.300 |  |
| Bi3+ + 3 e−  Bi(s) |  +0.308 |  |
| VO2+ + 2 H+ +  e−  V3+ +  H2O |  +0.34 |  |
| Cu2+ + 2 e−  Cu(s) |  +0.340 |  |
| Fe [Fe(CN)6]3− +  e−  [Fe(CN)6]4− |  +0.36 |  |
| O2(g) + 2 H2O + 4 e−  4 OH−(aq) |  +0.40 |  |
| Mo H2MoO4 + 6 H+ + 3 e−  Mo3+ + 2 H2O |  +0.43 |  |
| 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 |  |
| Cu+ +  e−  Cu(s) |  +0.520 |  |
| C CO(g) + 2 H+ + 2 e−  C(s) +  H2O |  +0.52 |  |
| I3− + 2 e−  3 I− |  +0.53 |  |
| I2(s) + 2 e−  2 I− |  +0.54 |  |
| 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 |  |
| Fc+ +  e−  Fc(s) |  +0.641 |  |
| Mo H2MoO4(aq) + 2 H+ + 2 e−  MoO2(s) + 2 H2O |  +0.65 |  |
| C  + 2 H+ + 2 e−   |  +0.6992 |  |
| 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 |  |
| Se H2SeO3(aq) + 4 H+ + 4 e−  Se(s) + 3 H2O |  +0.74 |  |
| PtCl42− + 2 e−  Pt(s) + 4 Cl− |  +0.758 |  |
| Fe3+ +  e−  Fe2+ |  +0.77 |  |
| Ag+ +  e−  Ag(s) |  +0.7996 |  |
| Hg22+ + 2 e−  2 Hg(l) |  +0.80 |  |
| N NO3−(aq) + 2 H+ +  e−  NO2(g) +  H2O |  +0.80 |  |
| FeO42− + 5 H2O + 6 e−  Fe2O3(s) + 10  OH− |  +0.81 |  |
| Au [AuBr4]− + 3 e−  Au(s) + 4 Br− |  +0.85 |  |
| Hg2+ + 2 e−  Hg(l) |  +0.85 |  |
| MnO4− +  H+ +  e−  HMnO4− |  +0.90 |  |
| Hg2 Hg2+ + 2 e−  Hg22+ |  +0.91 |  |
| Pd2+ + 2 e−  Pd(s) |  +0.915 |  |
| 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 |  |
| Xe[HXeO6]3− + 2 H2O + 2 e− +  [HXeO4]− + 4  OH− |  +0.99 |  |
| TeH6TeO6(aq) + 2 H+ + 2 e−  TeO2(s) + 4 H2O |  +1.02 |  |
| Br2(l) + 2 e−  2 Br− |  +1.066 |  |
| Br2(aq) + 2 e−  2 Br− |  +1.0873 |  |
| 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 |  |
| Xe[HXeO6]3− + 5 H2O + 8  e−  Xe(g) + 11 OH− |  +1.18 |  |
| Pt2+ + 2 e−  Pt(s) |  +1.188 |  |
| 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 |  +1.229 |  |
| MnO2(s) + 4 H+ + 2 e−  Mn2+ + 2 H2O |  +1.23 |  |
| Xe[HXeO4]− + 3 H2O + 6  e−  Xe(g) + 7 OH− |  +1.24 |  |
| Tl3+ + 2 e−  Tl+ |  +1.25 |  |
| Cr2O72− + 14 H+ + 6 e−  2 Cr3+ + 7 H2O |  +1.33 |  |
| Cl2(g) + 2 e−  2 Cl− |  +1.36 |  |
| CoO2(s) + 4 H+ +  e−  Co3+ + 2 H2O |  +1.42 |  |
| N 2 NH3O H+ +  H+ + 2 e−  N2H5+ + 2 H2O |  +1.42 |  |
| 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 |  |
| PbO α-PbO2(s) + 4 H+ + 2 e−  Pb2+ + 2 H2O |  +1.468 |  |
| 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 |  |
| MnO4− + 4 H+ + 3 e−  MnO2(s) + 2 H2O |  +1.70 |  |
| AgO(s) + 2 H+ +  e−  Ag+ +  H2O |  +1.77 |  |
| O  H2O2(aq) + 2 H+ + 2 e−  2 H2O |  +1.78 |  |
| Co3+ +  e−  Co2+ |  +1.82 |  |
| Au+ +  e−  Au(s) |  +1.83 |  |
| BrO4− + 2 H+ + 2 e−  BrO3− +  H2O |  +1.85 |  |
| Ag2+ +  e−  Ag+ |  +1.98 |  |
| S2O82− + 2 e−  2 SO42− |  +2.010 |  |
| O3(g) + 2 H+ + 2 e−  O2(g) +  H2O |  +2.075 |  |
| Mn HMnO4− + 3 H+ + 2 e−  MnO2(s) + 2 H2O |  +2.09 |  |
| XeO3(aq) + 6 H+ + 6  e−  Xe(g) + 3 H2O |  +2.12 |  |
| XeH4XeO6(aq) + 8 H+ + 8  e−  Xe(g) + 6  H2O |  +2.18 |  |
| FeO42− + 3 e− + 8 H+  Fe3+ + 4 H2O |  +2.20 |  |
| XeF2(aq) + 2 H+ + 2 e−  Xe(g) + 2HF(aq) |  +2.32 |  |
| XeH4XeO6(aq) + 2 H+ + 2 e−  XeO3(aq) +  H2O |  +2.42 |  |
| F2(g) + 2 e−  2 F− |  +2.87 |  |
| F2(g) + 2 H+ + 2 e−  2 HF(aq) |  +3.05 |  |
1 2  Not specified in the indicated reference, but assumed due to the difference between the value −0.454 and that computed by (2×−0.499 + −0.508) ÷ 3 = −0.502 exactly matching the difference between the values for white and red phosphorus in equilibrium with PH3.