Deret elektrokimia

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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 Sb Bi 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 (V) Ref.
& -9
Zz 9
3⁄​2N2(g) + H+ + e is in equilibrium with HN3(aq)  −3.09 [4]
Li+ + e is in equilibrium with Li(s)  −3.0401 [2]
N2(g) + 4H2O + 2e is in equilibrium with 2NH2OH(aq) + 2OH  −3.04 [4]
Cs+ + e is in equilibrium with Cs(s)  −3.026 [2]
Rb+ + e is in equilibrium with Rb(s)  −2.98 [2]
K+ + e is in equilibrium with K(s)  −2.931 [2]
Ba2+ + 2e is in equilibrium with Ba(s)  −2.912 [2]
La(OH)3(s) + 3e is in equilibrium with La(s) + 3OH  −2.90 [2]
Sr2+ + 2e is in equilibrium with Sr(s)  −2.899 [2]
Ca2+ + 2e is in equilibrium with Ca(s)  −2.868 [2]
Eu2+ + 2e is in equilibrium with Eu(s)  −2.812 [2]
Ra2+ + 2e is in equilibrium with Ra(s)  −2.8 [2]
Na+ + e is in equilibrium with Na(s)  −2.71 [7][2]
La3+ + 3e is in equilibrium with La(s)  −2.379 [2]
Y3+ + 3e is in equilibrium with Y(s)  −2.372 [2]
Mg2+ + 2e is in equilibrium with Mg(s)  −2.372 [2]
ZrO(OH)2(s) + H2O + 4e is in equilibrium with Zr(s) + 4OH  −2.36 [2]
Al(OH)4 + 3e is in equilibrium with Al(s) + 4OH  −2.33
Al(OH)3(s) + 3e is in equilibrium with Al(s) + 3OH  −2.31
H2(g) + 2e is in equilibrium with 2H  −2.25
Ac3+ + 3e is in equilibrium with Ac(s)  −2.20
Be2+ + 2e is in equilibrium with Be(s)  −1.85
U3+ + 3e is in equilibrium with U(s)  −1.66 [5]
Al3+ + 3e is in equilibrium with Al(s)  −1.66 [7]
Ti2+ + 2e is in equilibrium with Ti(s)  −1.63 [7]
ZrO2(s) + 4H+ + 4e is in equilibrium with Zr(s) + 2H2O  −1.553 [2]
Zr4+ + 4e is in equilibrium with Zr(s)  −1.45 [2]
Ti3+ + 3e is in equilibrium with Ti(s)  −1.37 [8]
TiO(s) + 2H+ + 2e is in equilibrium with Ti(s) + H2O  −1.31
Ti2O3(s) + 2H+ + 2e is in equilibrium with 2TiO(s) + H2O  −1.23
Zn(OH)42− + 2e is in equilibrium with Zn(s) + 4OH  −1.199 [2]
Mn2+ + 2e is in equilibrium with Mn(s)  −1.185 [2]
Fe(CN)64− + 6H+ + 2 e is in equilibrium with Fe(s) + 4HCN(aq)  −1.16 [9]
Te(s) + 2e is in equilibrium with Te2−  −1.143 [1]
V2+ + 2e is in equilibrium with V(s)  −1.13 [1]
Nb3+ + 3e is in equilibrium with Nb(s)  −1.099
Sn(s) + 4H+ + 4e is in equilibrium with SnH4(g)  −1.07
SiO2(s) + 4H+ + 4e is in equilibrium with Si(s) + 2H2O  −0.91
B(OH)3(aq) + 3H+ + 3e is in equilibrium with B(s) + 3H2O  −0.89
Fe(OH)2(s) + 2e is in equilibrium with Fe(s) + 2OH  −0.89 [9]
Fe2O3(s) + 3H2O + 2e is in equilibrium with 2Fe(OH)2(s) + 2OH  −0.86 [9]
TiO2+ + 2H+ + 4e is in equilibrium with Ti(s) + H2O  −0.86
2H2O + 2e is in equilibrium with H2(g) + 2OH  −0.8277 [2]
Bi(s) + 3H+ + 3e is in equilibrium with BiH3  −0.8 [2]
Zn2+ + 2e is in equilibrium with Zn(Hg)  −0.7628 [2]
Zn2+ + 2e is in equilibrium with Zn(s)  −0.7618 [2]
Ta2O5(s) + 10H+ + 10e is in equilibrium with 2Ta(s) + 5H2O  −0.75
Cr3+ + 3e is in equilibrium with Cr(s)  −0.74
[Au(CN)2] + e is in equilibrium with Au(s) + 2CN  −0.60
Ta3+ + 3e is in equilibrium with Ta(s)  −0.6
PbO(s) + H2O + 2e is in equilibrium with Pb(s) + 2OH  −0.58
2TiO2(s) + 2H+ + 2e is in equilibrium with Ti2O3(s) + H2O  −0.56
Ga3+ + 3e is in equilibrium with Ga(s)  −0.53
U4+ + e is in equilibrium with U3+  −0.52 [5]
H3PO2(aq) + H+ + e is in equilibrium with P(white)[note 1] + 2H2O  −0.508 [2]
H3PO3(aq) + 2H+ + 2e is in equilibrium with H3PO2(aq) + H2O  −0.499 [2]
H3PO3(aq) + 3H+ + 3e is in equilibrium with P(red)[note 1] + 3H2O  −0.454 [2]
Fe2+ + 2e is in equilibrium with Fe(s)  −0.44 [7]
2CO2(g) + 2H+ + 2e is in equilibrium with HOOCCOOH(aq)  −0.43
Cr3+ + e is in equilibrium with Cr2+  −0.42
Cd2+ + 2e is in equilibrium with Cd(s)  −0.40 [7]
GeO2(s) + 2H+ + 2e is in equilibrium with GeO(s) + H2O  −0.37
Cu2O(s) + H2O + 2e is in equilibrium with 2Cu(s) + 2OH  −0.360 [2]
PbSO4(s) + 2e is in equilibrium with Pb(s) + SO42−  −0.3588 [2]
PbSO4(s) + 2e is in equilibrium with Pb(Hg) + SO42−  −0.3505 [2]
Eu3+ + e is in equilibrium with Eu2+  −0.35 [5]
In3+ + 3e is in equilibrium with In(s)  −0.34 [1]
Tl+ + e is in equilibrium with Tl(s)  −0.34 [1]
Ge(s) + 4H+ + 4e is in equilibrium with GeH4(g)  −0.29
Co2+ + 2e is in equilibrium with Co(s)  −0.28 [2]
H3PO4(aq) + 2H+ + 2e is in equilibrium with H3PO3(aq) + H2O  −0.276 [2]
V3+ + e is in equilibrium with V2+  −0.26 [7]
Ni2+ + 2e is in equilibrium with Ni(s)  −0.25
As(s) + 3H+ + 3e is in equilibrium with AsH3(g)  −0.23 [1]
AgI(s) + e is in equilibrium with Ag(s) + I  −0.15224 [2]
MoO2(s) + 4H+ + 4e is in equilibrium with Mo(s) + 2H2O  −0.15
Si(s) + 4H+ + 4e is in equilibrium with SiH4(g)  −0.14
Sn2+ + 2e is in equilibrium with Sn(s)  −0.13
O2(g) + H+ + e is in equilibrium with HO2•(aq)  −0.13
Pb2+ + 2e is in equilibrium with Pb(s)  −0.13 [7]
WO2(s) + 4H+ + 4e is in equilibrium with W(s) + 2H2O  −0.12
P(red) + 3H+ + 3e is in equilibrium with PH3(g)  −0.111 [2]
CO2(g) + 2H+ + 2e is in equilibrium with HCOOH(aq)  −0.11
Se(s) + 2H+ + 2e is in equilibrium with H2Se(g)  −0.11
CO2(g) + 2H+ + 2e is in equilibrium with CO(g) + H2O  −0.11
SnO(s) + 2H+ + 2e is in equilibrium with Sn(s) + H2O  −0.10
SnO2(s) + 2H+ + 2e is in equilibrium with SnO(s) + H2O  −0.09
WO3(aq) + 6H+ + 6e is in equilibrium with W(s) + 3H2O  −0.09 [1]
P(white) + 3H+ + 3e is in equilibrium with PH3(g)  −0.063 [2]
Fe3+ + 3e is in equilibrium with Fe(s)  −0.04 [9]
HCOOH(aq) + 2H+ + 2e is in equilibrium with HCHO(aq) + H2O  −0.03
2H+ + 2e is in equilibrium with H2(g)    0.0000 ≡ 0
AgBr(s) + e is in equilibrium with Ag(s) + Br  +0.07133 [2]
S4O62− + 2e is in equilibrium with 2S2O32−  +0.08
Fe3O4(s) + 8H+ + 8e is in equilibrium with 3Fe(s) + 4H2O  +0.085 [6]
N2(g) + 2H2O + 6H+ + 6e is in equilibrium with 2NH4OH(aq)  +0.092
HgO(s) + H2O + 2e is in equilibrium with Hg(l) + 2OH  +0.0977
Cu(NH3)42+ + e is in equilibrium with Cu(NH3)2+ + 2NH3  +0.10 [1]
Ru(NH3)63+ + e is in equilibrium with Ru(NH3)62+  +0.10 [5]
N2H4(aq) + 4H2O + 2e is in equilibrium with 2NH4+ + 4OH  +0.11 [4]
H2MoO4(aq) + 6H+ + 6e is in equilibrium with Mo(s) + 4H2O  +0.11
Ge4+ + 4e is in equilibrium with Ge(s)  +0.12
C(s) + 4H+ + 4e is in equilibrium with CH4(g)  +0.13 [1]
HCHO(aq) + 2H+ + 2e is in equilibrium with CH3OH(aq)  +0.13
S(s) + 2H+ + 2e is in equilibrium with H2S(g)  +0.14
Sn4+ + 2e is in equilibrium with Sn2+  +0.15
Cu2+ + e is in equilibrium with Cu+  +0.159 [1]
HSO4 + 3H+ + 2e is in equilibrium with SO2(aq) + 2H2O  +0.16
UO22+ + e is in equilibrium with UO2+  +0.163 [5]
SO42− + 4H+ + 2e is in equilibrium with SO2(aq) + 2H2O  +0.17
TiO2+ + 2H+ + e is in equilibrium with Ti3+ + H2O  +0.19
SbO+ + 2H+ + 3e is in equilibrium with Sb(s) + H2O  +0.20
AgCl(s) + e is in equilibrium with Ag(s) + Cl  +0.22233 [2]
H3AsO3(aq) + 3H+ + 3e is in equilibrium with As(s) + 3H2O  +0.24
GeO(s) + 2H+ + 2e is in equilibrium with Ge(s) + H2O  +0.26
UO2+ + 4H+ + e is in equilibrium with U4+ + 2H2O  +0.273 [5]
Re3+ + 3e is in equilibrium with Re(s)  +0.300
Bi3+ + 3e is in equilibrium with Bi(s)  +0.308 [2]
VO2+ + 2H+ + e is in equilibrium with V3+ + H2O  +0.34
Cu2+ + 2e is in equilibrium with Cu(s)  +0.340 [1]
[Fe(CN)6]3− + e is in equilibrium with [Fe(CN)6]4−  +0.36
O2(g) + 2H2O + 4e is in equilibrium with 4OH(aq)  +0.40 [7]
H2MoO4 + 6H+ + 3e is in equilibrium with Mo3+ + 2H2O  +0.43
CH3OH(aq) + 2H+ + 2e is in equilibrium with CH4(g) + H2O  +0.50
SO2(aq) + 4H+ + 4e is in equilibrium with S(s) + 2H2O  +0.50
Cu+ + e is in equilibrium with Cu(s)  +0.520 [1]
CO(g) + 2H+ + 2e is in equilibrium with C(s) + H2O  +0.52
I3 + 2e is in equilibrium with 3I  +0.53 [7]
I2(s) + 2e is in equilibrium with 2I  +0.54 [7]
[AuI4] + 3e is in equilibrium with Au(s) + 4I  +0.56
H3AsO4(aq) + 2H+ + 2e is in equilibrium with H3AsO3(aq) + H2O  +0.56
[AuI2] + e is in equilibrium with Au(s) + 2I  +0.58
MnO4 + 2H2O + 3e is in equilibrium with MnO2(s) + 4OH  +0.59
S2O32 + 6H+ + 4e is in equilibrium with 2S(s) + 3H2O  +0.60
Fc+ + e is in equilibrium with Fc(s)  +0.641 [10]
H2MoO4(aq) + 2H+ + 2e is in equilibrium with MoO2(s) + 2H2O  +0.65
1,4-Benzochinon.svg + 2H+ + 2e is in equilibrium with Hydrochinon2.svg  +0.6992 [2]
O2(g) + 2H+ + 2e is in equilibrium with H2O2(aq)  +0.70
Tl3+ + 3e is in equilibrium with Tl(s)  +0.72
PtCl62− + 2e is in equilibrium with PtCl42− + 2Cl  +0.726 [5]
H2SeO3(aq) + 4H+ + 4e is in equilibrium with Se(s) + 3H2O  +0.74
PtCl42− + 2e is in equilibrium with Pt(s) + 4Cl  +0.758 [5]
Fe3+ + e is in equilibrium with Fe2+  +0.77
Ag+ + e is in equilibrium with Ag(s)  +0.7996 [2]
Hg22+ + 2e is in equilibrium with 2Hg(l)  +0.80
NO3(aq) + 2H+ + e is in equilibrium with NO2(g) + H2O  +0.80
FeO42− + 5H2O + 6e is in equilibrium with Fe2O3(s) + 10 OH  +0.81 [9]
[AuBr4] + 3e is in equilibrium with Au(s) + 4Br  +0.85
Hg2+ + 2e is in equilibrium with Hg(l)  +0.85
MnO4 + H+ + e is in equilibrium with HMnO4  +0.90
2Hg2+ + 2e is in equilibrium with Hg22+  +0.91 [1]
Pd2+ + 2e is in equilibrium with Pd(s)  +0.915 [5]
[AuCl4] + 3e is in equilibrium with Au(s) + 4Cl  +0.93
MnO2(s) + 4H+ + e is in equilibrium with Mn3+ + 2H2O  +0.95
[AuBr2] + e is in equilibrium with Au(s) + 2Br  +0.96
[HXeO6]3− + 2H2O + 2e + is in equilibrium with [HXeO4] + 4OH  +0.99 [11]
H6TeO6(aq) + 2H+ + 2e is in equilibrium with TeO2(s) + 4H2O  +1.02 [12]
Br2(l) + 2e is in equilibrium with 2Br  +1.066 [2]
Br2(aq) + 2e is in equilibrium with 2Br  +1.0873 [2]
IO3 + 5H+ + 4e is in equilibrium with HIO(aq) + 2H2O  +1.13
[AuCl2] + e is in equilibrium with Au(s) + 2Cl  +1.15
HSeO4 + 3H+ + 2e is in equilibrium with H2SeO3(aq) + H2O  +1.15
Ag2O(s) + 2H+ + 2e is in equilibrium with 2Ag(s) + H2O  +1.17
ClO3 + 2H+ + e is in equilibrium with ClO2(g) + H2O  +1.18
[HXeO6]3− + 5H2O + 8 e is in equilibrium with Xe(g) + 11OH  +1.18 [11]
Pt2+ + 2e is in equilibrium with Pt(s)  +1.188 [5]
ClO2(g) + H+ + e is in equilibrium with HClO2(aq)  +1.19
2IO3 + 12H+ + 10e is in equilibrium with I2(s) + 6H2O  +1.20
ClO4 + 2H+ + 2e is in equilibrium with ClO3 + H2O  +1.20
O2(g) + 4H+ + 4e is in equilibrium with 2H2O  +1.229 [7]
MnO2(s) + 4H+ + 2e is in equilibrium with Mn2+ + 2H2O  +1.23
[HXeO4] + 3H2O + 6 e is in equilibrium with Xe(g) + 7OH  +1.24 [11]
Tl3+ + 2e is in equilibrium with Tl+  +1.25
Cr2O72− + 14H+ + 6e is in equilibrium with 2Cr3+ + 7H2O  +1.33
Cl2(g) + 2e is in equilibrium with 2Cl  +1.36 [7]
CoO2(s) + 4H+ + e is in equilibrium with Co3+ + 2H2O  +1.42
2NH3OH+ + H+ + 2e is in equilibrium with N2H5+ + 2H2O  +1.42 [4]
2HIO(aq) + 2H+ + 2e is in equilibrium with I2(s) + 2H2O  +1.44
Ce4+ + e is in equilibrium with Ce3+  +1.44
BrO3 + 5H+ + 4e is in equilibrium with HBrO(aq) + 2H2O  +1.45
β-PbO2(s) + 4H+ + 2e is in equilibrium with Pb2+ + 2H2O  +1.460 [1]
α-PbO2(s) + 4H+ + 2e is in equilibrium with Pb2+ + 2H2O  +1.468 [1]
2BrO3 + 12H+ + 10e is in equilibrium with Br2(l) + 6H2O  +1.48
2ClO3 + 12H+ + 10e is in equilibrium with Cl2(g) + 6H2O  +1.49
MnO4 + 8H+ + 5e is in equilibrium with Mn2+ + 4H2O  +1.51
HO2 + H+ + e is in equilibrium with H2O2(aq)  +1.51
Au3+ + 3e is in equilibrium with Au(s)  +1.52
NiO2(s) + 4H+ + 2e is in equilibrium with Ni2+ + 2OH  +1.59
2HClO(aq) + 2H+ + 2e is in equilibrium with Cl2(g) + 2H2O  +1.63
Ag2O3(s) + 6H+ + 4e is in equilibrium with 2Ag+ + 3H2O  +1.67
HClO2(aq) + 2H+ + 2e is in equilibrium with HClO(aq) + H2O  +1.67
Pb4+ + 2e is in equilibrium with Pb2+  +1.69 [1]
MnO4 + 4H+ + 3e is in equilibrium with MnO2(s) + 2H2O  +1.70
AgO(s) + 2H+ + e is in equilibrium with Ag+ + H2O  +1.77
H2O2(aq) + 2H+ + 2e is in equilibrium with 2H2O  +1.78
Co3+ + e is in equilibrium with Co2+  +1.82
Au+ + e is in equilibrium with Au(s)  +1.83 [1]
BrO4 + 2H+ + 2e is in equilibrium with BrO3 + H2O  +1.85
Ag2+ + e is in equilibrium with Ag+  +1.98 [1]
S2O82− + 2e is in equilibrium with 2SO42−  +2.010 [2]
O3(g) + 2H+ + 2e is in equilibrium with O2(g) + H2O  +2.075 [5]
HMnO4 + 3H+ + 2e is in equilibrium with MnO2(s) + 2H2O  +2.09
XeO3(aq) + 6H+ + 6 e is in equilibrium with Xe(g) + 3H2O  +2.12 [11]
H4XeO6(aq) + 8H+ + 8 e is in equilibrium with Xe(g) + 6 H2O  +2.18 [11]
FeO42− + 3e + 8H+ is in equilibrium with Fe3+ + 4H2O  +2.20 [13]
XeF2(aq) + 2H+ + 2e is in equilibrium with Xe(g) + 2HF(aq)  +2.32 [11]
H4XeO6(aq) + 2H+ + 2e is in equilibrium with XeO3(aq) + H2O  +2.42 [11]
F2(g) + 2e is in equilibrium with 2F  +2.87 [1][7]
F2(g) + 2H+ + 2e is in equilibrium with 2HF(aq)  +3.05 [1]
  1. ^ a b 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.

Referensi[sunting | sunting sumber]

  1. ^ 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).
  2. ^ 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).
  3. ^ Vanýsek, Petr (2009). “Electrochemical Series”, in Handbook of Chemistry and Physics: 90th Edition (Chemical Rubber Company).
  4. ^ a b c d e Greenwood, Norman N.; Earnshaw, A. (1997), Chemistry of the Elements (ed. 2nd), Oxford: Butterworth-Heinemann, ISBN 0-7506-3365-4 
  5. ^ 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).
  6. ^ a b Marcel Pourbaix (1966). Atlas of Electrochemical Equilibria in Aqueous Solutions (NACE International, Houston, Texas; Cebelcor, Brussels).
  7. ^ a b c d e f g h i j k l m n Peter Atkins (1997). Physical Chemistry, 6th edition (W.H. Freeman and Company, New York).
  8. ^ a b Gordon Aylward & Tristan Findlay (2008). "SI Chemical Data", 6th edition (John Wiley & Sons, Australia), ISBN 978-0-470-81638-7.
  9. ^ a b c d e WebElements Periodic Table of the Elements | Iron | compounds information
  10. ^ Connelly, Neil G.; Geiger, William E. (1 January 1996). "Chemical Redox Agents for Organometallic Chemistry". Chemical Reviews 96 (2): 877–910. doi:10.1021/cr940053x. 
  11. ^ a b c d e f g WebElements Periodic Table of the Elements | Xenon | compounds information
  12. ^ Templat:Cotton&Wilkinson6th
  13. ^ Redox Reactions, Western Oregon University website