Deret elektrokimia
Urutan logam-logam
Deret elektrokimia atau deret Volta adalah urutan logam-logam (ditambah hidrogen) berdasarkan kenaikan potensial elektrode standarnya.[1] [2] [3] [4] [5] [6] [7] [8]
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):
- Legenda: (s)–padat; (l)–cair; (g)–gas; (aq)–larutan; (Hg)–amalgam.
| Setengah reaksi | E° (V) | Ref. |
|---|---|---|
3⁄2 N2(g) + H+ + e−  HN3(aq)
|
−3.09 | [4] |
| Li+ + e− Li(s)
|
−3.0401 | [2] |
| N2(g) + 4 H2O + 2 e− 2 NH2OH(aq) + 2 OH−
|
−3.04 | [4] |
| Cs+ + e− Cs(s)
|
−3.026 | [2] |
| Rb+ + e− Rb(s)
|
−2.98 | [2] |
| K+ + e− K(s)
|
−2.931 | [2] |
| Ba2+ + 2 e− Ba(s)
|
−2.912 | [2] |
| La(OH)3(s) + 3 e− La(s) + 3 OH−
|
−2.90 | [2] |
| Sr2+ + 2 e− Sr(s)
|
−2.899 | [2] |
| Ca2+ + 2 e− Ca(s)
|
−2.868 | [2] |
| Eu2+ + 2 e− Eu(s)
|
−2.812 | [2] |
| Ra2+ + 2 e− Ra(s)
|
−2.8 | [2] |
| Na+ + e− Na(s)
|
−2.71 | [2][7] |
| La3+ + 3 e− La(s)
|
−2.379 | [2] |
| Y3+ + 3 e− Y(s)
|
−2.372 | [2] |
| Mg2+ + 2 e− Mg(s)
|
−2.372 | [2] |
| ZrO(OH)2(s) + H2O + 4 e− Zr(s) + 4 OH−
|
−2.36 | [2] |
| Al(OH)4− + 3 e− Al(s) + 4 OH−
|
−2.33 | |
| Al(OH)3(s) + 3 e− Al(s) + 3 OH−
|
−2.31 | |
| H2(g) + 2 e− 2 H−
|
−2.25 | |
| Ac3+ + 3 e− Ac(s)
|
−2.20 | |
| Be2+ + 2 e− Be(s)
|
−1.85 | |
| U3+ + 3 e− U(s)
|
−1.66 | [5] |
| Al3+ + 3 e− Al(s)
|
−1.66 | [7] |
| Ti2+ + 2 e− Ti(s)
|
−1.63 | [7] |
| ZrO2(s) + 4 H+ + 4 e− Zr(s) + 2 H2O
|
−1.553 | [2] |
| Zr4+ + 4 e− Zr(s)
|
−1.45 | [2] |
| Ti3+ + 3 e− Ti(s)
|
−1.37 | [8] |
| TiO(s) + 2 H+ + 2 e− Ti(s) + H2O
|
−1.31 | |
| Ti2O3(s) + 2 H+ + 2 e− 2 TiO(s) + H2O
|
−1.23 | |
| Zn(OH)42− + 2 e− Zn(s) + 4 OH−
|
−1.199 | [2] |
| Mn2+ + 2 e− Mn(s)
|
−1.185 | [2] |
| Fe(CN)64− + 6 H+ + 2 e− Fe(s) + 4HCN(aq)
|
−1.16 | [9] |
| Te(s) + 2 e− Te2−
|
−1.143 | [1] |
| V2+ + 2 e− V(s)
|
−1.13 | [1] |
| Nb3+ + 3 e− Nb(s)
|
−1.099 | |
| Sn(s) + 4 H+ + 4 e− SnH4(g)
|
−1.07 | |
| SiO2(s) + 4 H+ + 4 e− Si(s) + 2 H2O
|
−0.91 | |
| B(OH)3(aq) + 3 H+ + 3 e− B(s) + 3 H2O
|
−0.89 | |
| Fe(OH)2(s) + 2 e− Fe(s) + 2 OH−
|
−0.89 | [9] |
| Fe2O3(s) + 3 H2O + 2 e− 2Fe(OH)2(s) + 2 OH−
|
−0.86 | [9] |
| TiO2+ + 2 H+ + 4 e− Ti(s) + H2O
|
−0.86 | |
| 2 H2O + 2 e− H2(g) + 2 OH−
|
−0.8277 | [2] |
| Bi(s) + 3 H+ + 3 e− BiH3
|
−0.8 | [2] |
| Zn2+ + 2 e− Zn(Hg)
|
−0.7628 | [2] |
| Zn2+ + 2 e− Zn(s)
|
−0.7618 | [2] |
| Ta2O5(s) + 10 H+ + 10 e− 2 Ta(s) + 5 H2O
|
−0.75 | |
| Cr3+ + 3 e− Cr(s)
|
−0.74 | |
| [Au(CN)2]− + e− Au(s) + 2 CN−
|
−0.60 | |
| Ta3+ + 3 e− Ta(s)
|
−0.6 | |
| PbO(s) + H2O + 2 e− Pb(s) + 2 OH−
|
−0.58 | |
| 2 TiO2(s) + 2 H+ + 2 e− Ti2O3(s) + H2O
|
−0.56 | |
| Ga3+ + 3 e− Ga(s)
|
−0.53 | |
| U4+ + e− U3+
|
−0.52 | [5] |
| H3PO2(aq) + H+ + e− P(white)[note 1] + 2 H2O
|
−0.508 | [2] |
| H3PO3(aq) + 2 H+ + 2 e− H3PO2(aq) + H2O
|
−0.499 | [2] |
| H3PO3(aq) + 3 H+ + 3 e− P(red)[note 1] + 3 H2O
|
−0.454 | [2] |
| Fe2+ + 2 e− Fe(s)
|
−0.44 | [7] |
| 2 CO2(g) + 2 H+ + 2 e− HOOCCOOH(aq)
|
−0.43 | |
| Cr3+ + e− Cr2+
|
−0.42 | |
| Cd2+ + 2 e− Cd(s)
|
−0.40 | [7] |
| GeO2(s) + 2 H+ + 2 e− GeO(s) + H2O
|
−0.37 | |
| Cu2O(s) + H2O + 2 e− 2 Cu(s) + 2 OH−
|
−0.360 | [2] |
| PbSO4(s) + 2 e− Pb(s) + SO42−
|
−0.3588 | [2] |
| PbSO4(s) + 2 e− Pb(Hg) + SO42−
|
−0.3505 | [2] |
| Eu3+ + e− Eu2+
|
−0.35 | [5] |
| In3+ + 3 e− In(s)
|
−0.34 | [1] |
| Tl+ + e− Tl(s)
|
−0.34 | [1] |
| Ge(s) + 4 H+ + 4 e− GeH4(g)
|
−0.29 | |
| Co2+ + 2 e− Co(s)
|
−0.28 | [2] |
| H3PO4(aq) + 2 H+ + 2 e− H3PO3(aq) + H2O
|
−0.276 | [2] |
| V3+ + e− V2+
|
−0.26 | [7] |
| Ni2+ + 2 e− Ni(s)
|
−0.25 | |
| As(s) + 3 H+ + 3 e− AsH3(g)
|
−0.23 | [1] |
| AgI(s) + e− Ag(s) + I−
|
−0.15224 | [2] |
| MoO2(s) + 4 H+ + 4 e− Mo(s) + 2 H2O
|
−0.15 | |
| Si(s) + 4 H+ + 4 e− SiH4(g)
|
−0.14 | |
| Sn2+ + 2 e− Sn(s)
|
−0.13 | |
| O2(g) + H+ + e− HO2•(aq)
|
−0.13 | |
| Pb2+ + 2 e− Pb(s)
|
−0.13 | [7] |
| WO2(s) + 4 H+ + 4 e− W(s) + 2 H2O
|
−0.12 | |
| P(red) + 3 H+ + 3 e− PH3(g)
|
−0.111 | [2] |
| CO2(g) + 2 H+ + 2 e− HCOOH(aq)
|
−0.11 | |
| Se(s) + 2 H+ + 2 e− H2Se(g)
|
−0.11 | |
| CO2(g) + 2 H+ + 2 e− CO(g) + H2O
|
−0.11 | |
| SnO(s) + 2 H+ + 2 e− Sn(s) + H2O
|
−0.10 | |
| SnO2(s) + 2 H+ + 2 e− SnO(s) + H2O
|
−0.09 | |
| WO3(aq) + 6 H+ + 6 e− W(s) + 3 H2O
|
−0.09 | [1] |
| P(white) + 3 H+ + 3 e− PH3(g)
|
−0.063 | [2] |
| Fe3+ + 3 e− Fe(s)
|
−0.04 | [9] |
| HCOOH(aq) + 2 H+ + 2 e− HCHO(aq) + H2O
|
−0.03 | |
| 2 H+ + 2 e− H2(g)
|
0.0000 | ≡ 0 |
| AgBr(s) + e− Ag(s) + Br−
|
+0.07133 | [2] |
| S4O62− + 2 e− 2 S2O32−
|
+0.08 | |
| Fe3O4(s) + 8 H+ + 8 e− 3 Fe(s) + 4 H2O
|
+0.085 | [6] |
| 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 | [1] |
| Ru(NH3)63+ + e− Ru(NH3)62+
|
+0.10 | [5] |
| N2H4(aq) + 4 H2O + 2 e− 2 NH4+ + 4 OH−
|
+0.11 | [4] |
| 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 | [1] |
| 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 | [1] |
| HSO4− + 3 H+ + 2 e− SO2(aq) + 2 H2O
|
+0.16 | |
| UO22+ + e− UO2+
|
+0.163 | [5] |
| 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 | [2] |
| 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 | [5] |
| Re3+ + 3 e− Re(s)
|
+0.300 | |
| Bi3+ + 3 e− Bi(s)
|
+0.308 | [2] |
| VO2+ + 2 H+ + e− V3+ + H2O
|
+0.34 | |
| Cu2+ + 2 e− Cu(s)
|
+0.340 | [1] |
| [Fe(CN)6]3− + e− [Fe(CN)6]4−
|
+0.36 | |
| O2(g) + 2 H2O + 4 e− 4 OH−(aq)
|
+0.40 | [7] |
| H2MoO4 + 6 H+ + 3 e− Mo3+ + 2 H2O
|
+0.43 | |
| CH3OH(aq) + 2 H+ + 2 e− CH4(g) + H2O
|
+0.50 | |
| SO2(aq) + 4 H+ + 4 e− S(s) + 2 H2O
|
+0.50 | |
| Cu+ + e− Cu(s)
|
+0.520 | [1] |
| CO(g) + 2 H+ + 2 e− C(s) + H2O
|
+0.52 | |
| I3− + 2 e− 3 I−
|
+0.53 | [7] |
| I2(s) + 2 e− 2 I−
|
+0.54 | [7] |
| [AuI4]− + 3 e− Au(s) + 4 I−
|
+0.56 | |
| H3AsO4(aq) + 2 H+ + 2 e− H3AsO3(aq) + H2O
|
+0.56 | |
| [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 | [10] |
| H2MoO4(aq) + 2 H+ + 2 e− MoO2(s) + 2 H2O
|
+0.65 | |
 + 2 H+ + 2 e− 
|
+0.6992 | [2] |
| 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 | [5] |
| H2SeO3(aq) + 4 H+ + 4 e− Se(s) + 3 H2O
|
+0.74 | |
| PtCl42− + 2 e− Pt(s) + 4 Cl−
|
+0.758 | [5] |
| Fe3+ + e− Fe2+
|
+0.77 | |
| Ag+ + e− Ag(s)
|
+0.7996 | [2] |
| Hg22+ + 2 e− 2 Hg(l)
|
+0.80 | |
| NO3−(aq) + 2 H+ + e− NO2(g) + H2O
|
+0.80 | |
| FeO42− + 5 H2O + 6 e− Fe2O3(s) + 10 OH−
|
+0.81 | [9] |
| [AuBr4]− + 3 e− Au(s) + 4 Br−
|
+0.85 | |
| Hg2+ + 2 e− Hg(l)
|
+0.85 | |
| MnO4− + H+ + e− HMnO4−
|
+0.90 | |
| 2 Hg2+ + 2 e− Hg22+
|
+0.91 | [1] |
| Pd2+ + 2 e− Pd(s)
|
+0.915 | [5] |
| [AuCl4]− + 3 e− Au(s) + 4 Cl−
|
+0.93 | |
| MnO2(s) + 4 H+ + e− Mn3+ + 2 H2O
|
+0.95 | |
| [AuBr2]− + e− Au(s) + 2 Br−
|
+0.96 | |
| [HXeO6]3− + 2 H2O + 2 e− + [HXeO4]− + 4 OH−
|
+0.99 | [11] |
| H6TeO6(aq) + 2 H+ + 2 e− TeO2(s) + 4 H2O
|
+1.02 | [12] |
| Br2(l) + 2 e− 2 Br−
|
+1.066 | [2] |
| Br2(aq) + 2 e− 2 Br−
|
+1.0873 | [2] |
| IO3− + 5 H+ + 4 e− HIO(aq) + 2 H2O
|
+1.13 | |
| [AuCl2]− + e− Au(s) + 2 Cl−
|
+1.15 | |
| 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 | |
| [HXeO6]3− + 5 H2O + 8 e− Xe(g) + 11 OH−
|
+1.18 | [11] |
| Pt2+ + 2 e− Pt(s)
|
+1.188 | [5] |
| ClO2(g) + H+ + e− HClO2(aq)
|
+1.19 | |
| 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 | [7] |
| MnO2(s) + 4 H+ + 2 e− Mn2+ + 2 H2O
|
+1.23 | |
| [HXeO4]− + 3 H2O + 6 e− Xe(g) + 7 OH−
|
+1.24 | [11] |
| 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 | [7] |
| CoO2(s) + 4 H+ + e− Co3+ + 2 H2O
|
+1.42 | |
| 2 NH3O H+ + H+ + 2 e− N2H5+ + 2 H2O
|
+1.42 | [4] |
| 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 | |
| β-PbO2(s) + 4 H+ + 2 e− Pb2+ + 2 H2O
|
+1.460 | [1] |
| α-PbO2(s) + 4 H+ + 2 e− Pb2+ + 2 H2O
|
+1.468 | [1] |
| 2 BrO3− + 12 H+ + 10 e− Br2(l) + 6 H2O
|
+1.48 | |
| 2ClO3− + 12 H+ + 10 e− Cl2(g) + 6 H2O
|
+1.49 | |
| MnO4− + 8 H+ + 5 e− Mn2+ + 4 H2O
|
+1.51 | |
| 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 | |
| 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 | |
| HClO2(aq) + 2 H+ + 2 e− HClO(aq) + H2O
|
+1.67 | |
| Pb4+ + 2 e− Pb2+
|
+1.69 | [1] |
| MnO4− + 4 H+ + 3 e− MnO2(s) + 2 H2O
|
+1.70 | |
| AgO(s) + 2 H+ + e− Ag+ + H2O
|
+1.77 | |
| H2O2(aq) + 2 H+ + 2 e− 2 H2O
|
+1.78 | |
| Co3+ + e− Co2+
|
+1.82 | |
| Au+ + e− Au(s)
|
+1.83 | [1] |
| BrO4− + 2 H+ + 2 e− BrO3− + H2O
|
+1.85 | |
| Ag2+ + e− Ag+
|
+1.98 | [1] |
| S2O82− + 2 e− 2 SO42−
|
+2.010 | [2] |
| O3(g) + 2 H+ + 2 e− O2(g) + H2O
|
+2.075 | [5] |
| HMnO4− + 3 H+ + 2 e− MnO2(s) + 2 H2O
|
+2.09 | |
| XeO3(aq) + 6 H+ + 6 e− Xe(g) + 3 H2O
|
+2.12 | [11] |
| H4XeO6(aq) + 8 H+ + 8 e− Xe(g) + 6 H2O
|
+2.18 | [11] |
| FeO42− + 3 e− + 8 H+ Fe3+ + 4 H2O
|
+2.20 | [13] |
| XeF2(aq) + 2 H+ + 2 e− Xe(g) + 2HF(aq)
|
+2.32 | [11] |
| H4XeO6(aq) + 2 H+ + 2 e− XeO3(aq) + H2O
|
+2.42 | [11] |
| F2(g) + 2 e− 2 F−
|
+2.87 | [1][7] |
| F2(g) + 2 H+ + 2 e− 2 HF(aq)
|
+3.05 | [1] |
Lihat pula
- Proteksi katodik
- Korosi galvanik
- Karat
- Pencegahan karat
- Proses Sendzimir
- Galvanisasi atau electroplating
- Redoks
Referensi
- ^ a b c d e f g h i j k l m n o p q r s t Bard, A. J., Parsons, R., and Jordan, J. (1985). Standard Potentials in Aqueous Solutions (Marcel Dekker, New York).
- ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq Vanýsek, Petr (2007). “Electrochemical Series”, in Handbook of Chemistry and Physics: 88th Edition (Chemical Rubber Company).
- ^ Vanýsek, Petr (2009). “Electrochemical Series”[pranala nonaktif permanen], in Handbook of Chemistry and Physics: 90th Edition Diarsipkan 2017-07-24 di Wayback Machine. (Chemical Rubber Company).
- ^ a b c d e Greenwood, Norman N.; Earnshaw, A. (1997), Chemistry of the Elements (edisi ke-2), Oxford: Butterworth-Heinemann, ISBN 0-7506-3365-4
- ^ a b c d e f g h i j k l Bard, A.J., Faulkner, L.R.(2001). Electrochemical Methods. Fundamentals and Applications, 2nd edition (John Wiley and Sons Inc).
- ^ a b Marcel Pourbaix (1966). Atlas of Electrochemical Equilibria in Aqueous Solutions (NACE International, Houston, Texas; Cebelcor, Brussels).
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