183:, slow electrode kinetics, non-equilibrium, presence of multiple redox couples, electrode poisoning, small exchange currents, and inert redox couples. Consequently, practical measurements seldom correlate with calculated values. Nevertheless, reduction potential measurement has proven useful as an analytical tool in monitoring changes in a system rather than determining their absolute value (e.g. process control and
588:
potential (where pH neutral water is set to 0 V) is analogous with redox potential (where standardized hydrogen solution is set to 0 V), but instead of hydrogen ions, electrons are transferred across in the redox case. Both pH and redox potentials are properties of solutions, not of elements or chemical compounds themselves, and depend on concentrations, temperature etc.
599:, which are said to "be reduced by" the reducer. The reducer is stronger when it has a more negative reduction potential and weaker when it has a more positive reduction potential. The more positive the reduction potential the greater the species' affinity for electrons and tendency to be reduced. The following table provides the reduction potentials of the indicated
2797:, usually have oxidizing conditions (positive potentials). In places with limitations in air supply, such as submerged soils, swamps and marine sediments, reducing conditions (negative potentials) are the norm. Intermediate values are rare and usually a temporary condition found in systems moving to higher or lower pe values.
2036:
2800:
In environmental situations, it is common to have complex non-equilibrium conditions between a large number of species, meaning that it is often not possible to make accurate and precise measurements of the reduction potential. However, it is usually possible to obtain an approximate value and define
1423:
Absolute reduction potentials can be determined if one knows the actual potential between electrode and electrolyte for any one reaction. Surface polarization interferes with measurements, but various sources give an estimated potential for the standard hydrogen electrode of 4.4 V to 4.6 V
583:
at room temperature. This notion is useful for understanding redox potential, although the transfer of electrons, rather than the absolute concentration of free electrons in thermal equilibrium, is how one usually thinks of redox potential. Theoretically, however, the two approaches are equivalent.
1117:(SHE) used as reference electrode, which is arbitrarily given a potential of 0.00 V. However, because these can also be referred to as "redox potentials", the terms "reduction potentials" and "oxidation potentials" are preferred by the IUPAC. The two may be explicitly distinguished by the symbols
135:
is a measure of the tendency of the solution to either gain or lose electrons in a reaction. A solution with a higher (more positive) reduction potential than some other molecule will have a tendency to gain electrons from this molecule (i.e. to be reduced by oxidizing this other molecule) and a
587:
Conversely, one could define a potential corresponding to pH as a potential difference between a solute and pH neutral water, separated by porous membrane (that is permeable to hydrogen ions). Such potential differences actually do occur from differences in acidity on biological membranes. This
199:
of an aqueous solution, the tendency of electron transfer between a chemical species and an electrode determines the redox potential of an electrode couple. Like pH, redox potential represents how easily electrons are transferred to or from species in solution. Redox potential characterises the
140:
are next to impossible to accurately measure, reduction potentials are defined relative to a reference electrode. Reduction potentials of aqueous solutions are determined by measuring the potential difference between an inert sensing electrode in contact with the solution and a stable reference
119:(V). Each species has its own intrinsic redox potential; for example, the more positive the reduction potential (reduction potential is more often used due to general formalism in electrochemistry), the greater the species' affinity for electrons and tendency to be reduced.
2539:
reactions are oxidation–reduction reactions, in which one compound is oxidized and another compound is reduced. The ability of an organism to carry out oxidation–reduction reactions depends on the oxidation–reduction state of the environment, or its reduction potential
168:(SHE) is the reference from which all standard redox potentials are determined, and has been assigned an arbitrary half cell potential of 0.0 V. However, it is fragile and impractical for routine laboratory use. Therefore, other more stable reference electrodes such as
2813:
The oxido-reduction potential (ORP) can be used for the systems monitoring water quality with the advantage of a single-value measure for the disinfection potential, showing the effective activity of the disinfectant rather than the applied dose. For example,
1289:
Any system or environment that accepts electrons from a normal hydrogen electrode is a half cell that is defined as having a positive redox potential; any system donating electrons to the hydrogen electrode is defined as having a negative redox potential.
1860:
2705:
mark in superscript) calculated at pH 7 closer to the pH of biological and intra-cellular fluids are used to more easily assess if a given biochemical redox reaction is possible. They must not be confused with the common standard reduction potentials
2804:
In the soil there are two main redox constituents: 1) anorganic redox systems (mainly ox/red compounds of Fe and Mn) and measurement in water extracts; 2) natural soil samples with all microbial and root components and measurement by direct method.
321:
1772:
1427:
Half-cell equations can be combined if the one corresponding to oxidation is reversed so that each electron given by the reductant is accepted by the oxidant. In this way, the global combined equation no longer contains electrons.
1655:
2312:
If, in very rare instances of reduction reactions, the H were the products formed by a reduction reaction and thus appearing on the right side of the equation, the slope of the line would be inverse and thus positive (higher
2964:
2530:
985:
2895:
evaluations at the same time are necessary. Nevertheless, the equilibrium conditions can be used to evaluate the direction of spontaneous changes and the magnitude of the driving force behind them.
2115:
2793:
The reduction potentials in natural systems often lie comparatively near one of the boundaries of the stability region of water. Aerated surface water, rivers, lakes, oceans, rainwater and
2031:{\displaystyle E_{h}=E_{\text{red}}=E_{\text{red}}^{\ominus }-{\frac {0.05916}{z}}\log \left({\frac {\{C\}^{c}\{D\}^{d}}{\{A\}^{a}\{B\}^{b}}}\right)-{\frac {0.05916\,h}{z}}{\text{pH}}}
1693:
136:
solution with a lower (more negative) reduction potential will have a tendency to lose electrons to other substances (i.e. to be oxidized by reducing the other substance). Because the
2697:
179:
Although measurement of the redox potential in aqueous solutions is relatively straightforward, many factors limit its interpretation, such as effects of solution temperature and pH,
369:
2469:
1805:
2744:
1284:
1111:
1029:
228:
1230:
581:
466:
3275:
Onishi, j; Kondo W; Uchiyama Y (1960). "Preliminary report on the oxidation-reduction potential obtained on surfaces of gingiva and tongue and in interdental space".
1148:
619:(Cl) ion, it is Na metal that is the strongest reducing agent while Cl ion is the weakest; said differently, Na ion is the weakest oxidizing agent in this list while
77:
1178:
2630:
2599:
2565:
2338:
2145:
2073:
1852:
1507:
1467:
1381:
1350:
1315:
516:
105:
1701:
2786:
In the field of environmental chemistry, the reduction potential is used to determine if oxidizing or reducing conditions are prevalent in water or soil, and to
539:
489:
200:
ability under the specific condition of a chemical species to lose or gain electrons instead of the amount of electrons available for oxidation or reduction.
2639:
There are organisms that can adjust their metabolism to their environment, such as facultative anaerobes. Facultative anaerobes can be active at positive
1529:
2832:
and other pathogens have survival times of less than 30 seconds when the ORP is above 665 mV, compared to more than 300 seconds when ORP is below 485 mV.
1420:, as occurs in the absence of water. It is the reduction potential of each species present that will determine which species will be oxidized or reduced.
468:
is defined as the negative logarithm of the free electron concentration in solution, and is directly proportional to the redox potential. Sometimes
2790:, such as dissolved metals. pe values in water range from -12 to 25; the levels where the water itself becomes reduced or oxidized, respectively.
3118:) measurement for characterisation of soil properties. Application for comparison of conventional and conservation agriculture cropping systems.
2891:
may be predicted to occur under a set of conditions, the process may practically be negligible because its rate is too slow. Consequently,
2305:
This is why protons are always engaged as reagent on the left side of the reduction reactions as can be generally observed in the table of
2851:. The results of this study presents arguments in favor of the inclusion of ORP above 650 mV in the local health regulation codes.
942:
Hydrogen (whose reduction potential is 0.0) acts as an oxidizing agent because it accepts an electron donation from the reducing agent
1286:
means there is a greater tendency for reduction to occur, while a lower one means there is a greater tendency for oxidation to occur.
2306:
981:
3153:"Do Traditional Measures of Water Quality in Swimming Pools and Spas Correspond with Beneficial Oxidation Reduction Potential?"
2959:
2879:
is predicted to be the most stable form of an element, these diagrams show that mineral. As the predicted results are all from
3003:
3072:
Chuan, M.; Liu, G. Shu. J. (1996). "Solubility of heavy metals in a contaminated soil: Effects of redox potential and pH".
2209:) being in excess are freed-up when the central atom is reduced. The acid-base neutralization of each oxide ion consumes 2
2078:
2929:
2871:–pH (Pourbaix) diagrams are commonly used in mining and geology for assessment of the stability fields of minerals and
591:
The table below shows a few reduction potentials, which can be changed to oxidation potentials by reversing the sign.
3309:
964:
Hydrogen acts as a reducing agent because it donates its electrons to fluorine, which allows fluorine to be reduced.
928:. Hydrogen gas is a reducing agent when it reacts with non-metals and an oxidizing agent when it reacts with metals.
2198:
In most (if not all) of the reduction reactions involving oxyanions with a central redox-active atom, oxide anions (
633:
17:
1666:
2954:
1661:
991:
973:
329:
137:
2659:
2454:
1780:
1114:
977:
173:
165:
2711:
1251:
1078:
996:
2400:(in which dissolved iron, Fe(II), is divalent and much more soluble than Fe(III)), while releasing one
2887:) evaluations, these diagrams should be used with caution. Although the formation of a mineral or its
3028:
2904:
2884:
1183:
392:
169:
544:
316:{\displaystyle pe={\frac {E_{H}}{V_{T}\lambda }}={\frac {E_{H}}{0.05916}}=16.903\,{\text{×}}\,E_{H}}
164:
can be used as well. The reference half cell consists of a redox standard of known potential. The
2888:
946:(whose reduction potential is -3.04), which causes Li to be oxidized and Hydrogen to be reduced.
115:
to an electrode and thereby be reduced or oxidised respectively. Redox potential is expressed in
3018:
Stumm, W. and Morgan, J. J. (1981). Aquatic
Chemistry, 2nd Ed., John Wiley & Sons, New York.
1394:, water, rather than the solute, is oxidized or reduced. For example, if an aqueous solution of
1241:
420:
3294:
2653:
values in the presence of oxygen-bearing inorganic compounds, such as nitrates and sulfates.
1820:
1120:
49:
1767:{\displaystyle E_{\text{red}}^{\ominus }({\text{volts}})=-{\frac {\Delta G^{\ominus }}{zF}}}
1153:
3136:
Oxidation-Reduction
Potential for Water Disinfection Monitoring, Control, and Documentation
3081:
2892:
2608:
2577:
2543:
2316:
2123:
2051:
2043:
1830:
1485:
1445:
1359:
1328:
1293:
1044:
494:
83:
8:
2914:
2749:
1032:
180:
3289:
3085:
521:
471:
148:
The sensing electrode acts as a platform for electron transfer to or from the reference
3177:
3152:
3097:
3058:
2840:
2836:
2487:
2404:
2213:
1650:{\displaystyle a\,A+b\,B+h\,{\ce {H+}}+z\,e^{-}\quad {\ce {<=>}}\quad c\,C+d\,D}
3182:
2999:
2949:
2909:
2764:) with the concentration of each dissolved species being taken as 1 M, and thus
1808:
1056:
3202:
3101:
3172:
3164:
3089:
2934:
2860:
2787:
2781:
2531:
Table of standard reduction potentials for half-reactions important in biochemistry
1478:
1391:
1060:
986:
Table of standard reduction potentials for half-reactions important in biochemistry
596:
404:
208:
128:
108:
2510:
Note that the slope 0.0296 of the line is −1/2 of the −0.05916 value above, since
2844:
2794:
1824:
1474:
1437:
1395:
925:
372:
2656:
In biochemistry, apparent standard reduction potentials, or formal potentials, (
3168:
2944:
2880:
2876:
600:
592:
3303:
3244:
3221:
3139:
2924:
195:
Similar to how the concentration of hydrogen ions determines the acidity or
3186:
1387:
380:
3114:
Husson O. et al. (2016). Practical improvements in soil redox potential (E
2919:
142:
3093:
2872:
2822:
1064:
1040:
2848:
2344:
1516:
1410:
1352:
indicates an environment that favors oxidation reaction such as free
1322:
1245:
184:
149:
1248:
can be compared to predict the direction of electron flow. A higher
176:(SCE) are commonly used because of their more reliable performance.
2989:
2987:
2985:
2983:
2981:
2979:
2828:
2633:
2602:
1403:
616:
608:
161:
153:
112:
2521:. Note also that the value –0.0885 corresponds to –0.05916 × 3/2.
2816:
1399:
1036:
943:
612:
2976:
27:
Measure of the tendency of a substance to gain or lose electrons
2571:
2536:
1414:
1353:
604:
396:
2965:
Standard apparent reduction potentials in biochemistry at pH 7
1383:
indicates a strong reducing environment, such as free metals.
2996:
Environmental
Chemistry -(*Gary Wallace) a global perspective
2939:
2801:
the conditions as being in the oxidizing or reducing regime.
2788:
predict the states of different chemical species in the water
2218:
1072:
518:, for example, in environmental chemistry. If one normalizes
2147:
at higher pH values. This is observed for the reduction of O
3052:
2998:(3rd ed.). Oxford University Press. pp. 235–248.
1318:
157:
116:
1519:
equation, conventionally written as a reduction reaction (
2343:
An example of that would be the reductive dissolution of
1068:
1052:
3274:
3203:
Online
Calculator Redoxpotential ("Redox Compensation")
2767:
1510:
1470:
215:
is a dimensionless number and can easily be related to
196:
1609:
1523:, electrons accepted by an oxidant on the left side):
1075:
in their pure state. The standard reduction potential
2993:
2714:
2662:
2611:
2580:
2546:
2457:
2319:
2126:
2110:{\displaystyle -0.05916\,\left({\frac {h}{z}}\right)}
2081:
2054:
2048:
This equation is the equation of a straight line for
2046:, and exponents are shown in the conventional manner.
1863:
1833:
1783:
1704:
1669:
1532:
1488:
1448:
1362:
1331:
1296:
1254:
1186:
1156:
1123:
1081:
999:
547:
524:
497:
474:
423:
332:
231:
86:
52:
924:
Some elements and compounds can be both reducing or
491:
is used as a unit of reduction potential instead of
2738:
2691:
2624:
2593:
2559:
2463:
2332:
2139:
2109:
2067:
2030:
1846:
1799:
1766:
1687:
1649:
1501:
1461:
1375:
1344:
1309:
1278:
1224:
1172:
1142:
1105:
1023:
575:
533:
510:
483:
460:
363:
315:
99:
71:
1617:
1616:
1599:
1598:
122:
3301:
3295:Oxidizing and Reducing Agents in Redox Reactions
3290:Redox potential exercices in biological systems
967:
3150:
2875:species. Under the conditions where a mineral
2854:
541:of hydrogen to zero, one obtains the relation
1398:is electrolyzed, water may be reduced at the
2835:A study was conducted comparing traditional
1988:
1981:
1972:
1965:
1954:
1947:
1938:
1931:
3140:http://anrcatalog.ucdavis.edu/pdf/8149.pdf
3108:
2775:
631:Reduction potentials of various reactions
3176:
2088:
2013:
1815:is the number of electrons involved, and
1688:{\displaystyle E_{\text{red}}^{\ominus }}
1643:
1633:
1575:
1556:
1546:
1536:
302:
296:
141:electrode connected to the solution by a
3130:
3128:
3071:
2632:values. Redox affects the solubility of
2307:standard reduction potential (data page)
982:Standard electrode potential (data page)
2155:O, or OH, and for reduction of H into H
1592:
14:
3302:
3151:Bastian, Tiana; Brondum, Jack (2009).
3053:Garrels, R. M.; Christ, C. L. (1990).
3046:
2994:vanLoon, Gary; Duffy, Stephen (2011).
2960:Table of standard electrode potentials
399:(298.15 K = 25 °C = 77 °F),
3125:
1413:ions, instead of Na being reduced to
364:{\displaystyle V_{T}={\frac {RT}{F}}}
2075:as a function of pH with a slope of
107:) is a measure of the tendency of a
3283:
3269:
3055:Minerals, Solutions, and Equilibria
2692:{\displaystyle E_{red}^{\ominus '}}
2505:= −1.1819 − 0.0885 log + 0.0296 pH
2464:{\displaystyle \rightleftharpoons }
1800:{\displaystyle \Delta G^{\ominus }}
1071:taking part into the reaction, and
24:
3138:, University of California Davis,
2930:Oxygen radical absorbance capacity
2739:{\displaystyle E_{red}^{\ominus }}
1784:
1740:
1431:
1424:(the electrolyte being positive).
1279:{\displaystyle E_{red}^{\ominus }}
1106:{\displaystyle E_{red}^{\ominus }}
1024:{\displaystyle E_{red}^{\ominus }}
603:at 25 °C. For example, among
595:donate electrons to (or "reduce")
111:to acquire electrons from or lose
25:
3321:
3196:
2605:are generally active at negative
2574:are generally active at positive
1473:of a solution are related by the
3074:Water, Air, & Soil Pollution
2808:
3144:
3029:"Standard Electrode Potentials"
2524:
1629:
1586:
1225:{\displaystyle E_{ox}=-E_{red}}
222:by the following relationship:
35:oxidation / reduction potential
3238:
3215:
3065:
3021:
3012:
2458:
2042:where curly brackets indicate
1728:
1720:
1619:
1594:
576:{\displaystyle pe=16.9\ E_{h}}
455:
442:
190:
123:Measurement and interpretation
13:
1:
3033:hyperphysics.phy-astr.gsu.edu
2970:
2120:This equation predicts lower
1477:as commonly represented by a
1235:
2955:Standard electrode potential
2754:T = 298.15 K = 25 °C = 77 °F
1662:standard reduction potential
992:standard reduction potential
974:Standard electrode potential
968:Standard reduction potential
414:), and λ = ln(10) ≈ 2.3026.
407:(96 485 coulomb/mol of
7:
3226:2 Li (s) → 2 Li (s) + 2 e
2898:
2855:Geochemistry and mineralogy
1115:standard hydrogen electrode
1113:is defined relative to the
978:Standard hydrogen electrode
626:molecule is the strongest.
166:standard hydrogen electrode
10:
3326:
3169:10.1177/003335490912400213
2858:
2779:
2528:
1435:
971:
660:
152:; it is typically made of
2905:Electrochemical potential
2636:, especially metal ions.
3310:Electrochemical concepts
3277:Bull Tokyo Med Dent Univ
3208:
3134:Trevor V. Suslow, 2004.
2646:values, and at negative
2117:volt (pH has no units).
1317:is usually expressed in
461:{\displaystyle pe=-\log}
2776:Environmental chemistry
2601:values, whereas strict
1143:{\displaystyle E_{red}}
1055:participating into the
72:{\displaystyle E_{red}}
3120:Analytica Chimica Acta
2740:
2693:
2626:
2595:
2572:aerobic microorganisms
2561:
2465:
2334:
2141:
2111:
2069:
2032:
1848:
1801:
1768:
1689:
1651:
1503:
1463:
1377:
1346:
1311:
1280:
1226:
1174:
1173:{\displaystyle E_{ox}}
1144:
1107:
1025:
577:
535:
512:
485:
462:
365:
317:
181:irreversible reactions
101:
73:
3261:(g) + 2 e → 2 F (g)
3255:combined along with:
3253:(g) → 2 H (g) + 2 e
3234:(g) → 2 H (g) + 2 e
3228:combined along with:
2741:
2699:, noted with a prime
2694:
2627:
2625:{\displaystyle E_{h}}
2596:
2594:{\displaystyle E_{h}}
2562:
2560:{\displaystyle E_{h}}
2466:
2335:
2333:{\displaystyle E_{h}}
2226:molecule as follows:
2142:
2140:{\displaystyle E_{h}}
2112:
2070:
2068:{\displaystyle E_{h}}
2033:
1849:
1847:{\displaystyle E_{h}}
1802:
1769:
1690:
1652:
1504:
1502:{\displaystyle E_{h}}
1464:
1462:{\displaystyle E_{h}}
1390:is carried out in an
1378:
1376:{\displaystyle E_{h}}
1347:
1345:{\displaystyle E_{h}}
1312:
1310:{\displaystyle E_{h}}
1281:
1227:
1175:
1145:
1108:
1026:
578:
536:
513:
511:{\displaystyle E_{h}}
486:
463:
366:
318:
102:
100:{\displaystyle E_{h}}
74:
2712:
2660:
2609:
2578:
2544:
2455:
2317:
2124:
2079:
2052:
1861:
1831:
1781:
1702:
1667:
1530:
1486:
1446:
1360:
1329:
1294:
1252:
1184:
1154:
1121:
1079:
997:
545:
522:
495:
472:
421:
393:absolute temperature
330:
229:
84:
50:
3086:1996WASP...90..543C
2915:Electromotive force
2843:reading and ORP in
2762:= 1 atm = 1.013 bar
2750:standard conditions
2735:
2688:
2168:+ 4 H + 4 e ⇌ 2 H
1904:
1719:
1684:
1605:
1325:). A high positive
1321:(V) or millivolts (
1275:
1102:
1035:: T = 298.15 K (25
1033:standard conditions
1020:
637:
138:absolute potentials
3094:10.1007/BF00282668
3059:Jones and Bartlett
2736:
2715:
2689:
2663:
2622:
2591:
2557:
2461:
2330:
2137:
2107:
2065:
2028:
1890:
1844:
1821:Faraday's constant
1797:
1764:
1705:
1685:
1670:
1647:
1624:
1499:
1459:
1373:
1342:
1307:
1276:
1255:
1222:
1170:
1140:
1103:
1082:
1031:is measured under
1021:
1000:
630:
573:
534:{\displaystyle pe}
531:
508:
484:{\displaystyle pe}
481:
458:
385:8.314 J⋅K⋅mol
361:
313:
97:
69:
3157:Public Health Rep
3005:978-0-19-922886-7
2950:Solvated electron
2910:Electrolytic cell
2885:equilibrium state
2837:parts per million
2748:determined under
2101:
2026:
2021:
1998:
1916:
1897:
1884:
1809:Gibbs free energy
1762:
1726:
1712:
1677:
1626:
1561:
1356:. A low negative
937:(g) → 2 LiH (s)
921:
920:
636:
562:
359:
300:
288:
268:
209:Pourbaix diagrams
174:saturated calomel
129:aqueous solutions
16:(Redirected from
3317:
3280:
3270:Additional notes
3263:
3262:
3254:
3242:
3236:
3235:
3227:
3219:
3191:
3190:
3180:
3148:
3142:
3132:
3123:
3112:
3106:
3105:
3080:(3–4): 543–556.
3069:
3063:
3062:
3050:
3044:
3043:
3041:
3039:
3025:
3019:
3016:
3010:
3009:
2991:
2935:Pourbaix diagram
2861:Pourbaix diagram
2782:Pourbaix diagram
2771:
2763:
2755:
2747:
2745:
2743:
2742:
2737:
2734:
2729:
2703:
2698:
2696:
2695:
2690:
2687:
2686:
2677:
2631:
2629:
2628:
2623:
2621:
2620:
2600:
2598:
2597:
2592:
2590:
2589:
2566:
2564:
2563:
2558:
2556:
2555:
2520:
2506:
2490:
2486:
2482:
2481:
2480:
2470:
2468:
2467:
2462:
2448:
2444:
2442:
2441:
2431:
2430:
2429:
2421:
2420:
2403:
2399:
2398:
2391:) to form 3 HFeO
2390:
2389:
2388:
2379:
2378:
2377:
2368:
2357:
2339:
2337:
2336:
2331:
2329:
2328:
2301:
2300:
2299:
2290:
2288:
2287:
2277:
2276:
2275:
2263:
2261:
2260:
2250:
2249:
2248:
2239:
2238:
2237:
2225:
2212:
2208:
2207:
2206:
2194:
2186:
2185:O + 4 e ⇌ 4 OH
2173:
2146:
2144:
2143:
2138:
2136:
2135:
2116:
2114:
2113:
2108:
2106:
2102:
2094:
2074:
2072:
2071:
2066:
2064:
2063:
2037:
2035:
2034:
2029:
2027:
2024:
2022:
2017:
2008:
2003:
1999:
1997:
1996:
1995:
1980:
1979:
1963:
1962:
1961:
1946:
1945:
1929:
1917:
1909:
1903:
1898:
1895:
1886:
1885:
1882:
1873:
1872:
1853:
1851:
1850:
1845:
1843:
1842:
1818:
1814:
1807:is the standard
1806:
1804:
1803:
1798:
1796:
1795:
1773:
1771:
1770:
1765:
1763:
1761:
1753:
1752:
1751:
1738:
1727:
1724:
1718:
1713:
1710:
1694:
1692:
1691:
1686:
1683:
1678:
1675:
1656:
1654:
1653:
1648:
1628:
1627:
1625:
1623:
1622:
1615:
1607:
1606:
1604:
1597:
1589:
1585:
1584:
1568:
1567:
1566:
1559:
1514:
1508:
1506:
1505:
1500:
1498:
1497:
1479:Pourbaix diagram
1468:
1466:
1465:
1460:
1458:
1457:
1392:aqueous solution
1382:
1380:
1379:
1374:
1372:
1371:
1351:
1349:
1348:
1343:
1341:
1340:
1316:
1314:
1313:
1308:
1306:
1305:
1285:
1283:
1282:
1277:
1274:
1269:
1231:
1229:
1228:
1223:
1221:
1220:
1199:
1198:
1179:
1177:
1176:
1171:
1169:
1168:
1149:
1147:
1146:
1141:
1139:
1138:
1112:
1110:
1109:
1104:
1101:
1096:
1061:partial pressure
1050:
1030:
1028:
1027:
1022:
1019:
1014:
960:
959:(g) → 2 HF (g)
938:
926:oxidizing agents
914:
909:
895:
886:
884:
883:
880:
867:
862:
848:
843:
829:
824:
814:
809:
799:
794:
784:
776:
766:
761:
751:
746:
736:
727:
713:
708:
698:
693:
683:
678:
668:
663:
658:
638:
632:
629:
625:
597:oxidizing agents
582:
580:
579:
574:
572:
571:
560:
540:
538:
537:
532:
517:
515:
514:
509:
507:
506:
490:
488:
487:
482:
467:
465:
464:
459:
454:
453:
410:
405:Faraday constant
402:
390:
386:
378:
370:
368:
367:
362:
360:
355:
347:
342:
341:
322:
320:
319:
314:
312:
311:
301:
298:
289:
284:
283:
274:
269:
267:
263:
262:
252:
251:
242:
214:
206:
109:chemical species
106:
104:
103:
98:
96:
95:
78:
76:
75:
70:
68:
67:
21:
3325:
3324:
3320:
3319:
3318:
3316:
3315:
3314:
3300:
3299:
3286:
3272:
3267:
3266:
3260:
3256:
3252:
3248:
3243:
3239:
3233:
3229:
3225:
3220:
3216:
3211:
3199:
3194:
3149:
3145:
3133:
3126:
3117:
3113:
3109:
3070:
3066:
3051:
3047:
3037:
3035:
3027:
3026:
3022:
3017:
3013:
3006:
2992:
2977:
2973:
2901:
2869:
2863:
2857:
2845:Hennepin County
2811:
2795:acid mine water
2784:
2778:
2765:
2761:
2757:
2753:
2730:
2719:
2713:
2710:
2709:
2707:
2701:
2679:
2678:
2667:
2661:
2658:
2657:
2651:
2644:
2616:
2612:
2610:
2607:
2606:
2585:
2581:
2579:
2576:
2575:
2551:
2547:
2545:
2542:
2541:
2533:
2527:
2511:
2503:
2498:
2484:
2479:
2476:
2475:
2474:
2472:
2456:
2453:
2452:
2446:
2440:
2437:
2436:
2435:
2433:
2428:
2425:
2424:
2423:
2419:
2416:
2415:
2414:
2412:
2411:
2401:
2397:
2394:
2393:
2392:
2387:
2385:
2384:
2383:
2381:
2376:
2374:
2373:
2372:
2370:
2367:
2363:
2359:
2356:
2352:
2348:
2340:at higher pH).
2324:
2320:
2318:
2315:
2314:
2298:
2296:
2295:
2294:
2292:
2286:
2283:
2282:
2281:
2279:
2274:
2272:
2271:
2270:
2268:
2259:
2256:
2255:
2254:
2252:
2247:
2245:
2244:
2243:
2241:
2236:
2234:
2233:
2232:
2230:
2222:
2217:
2210:
2205:
2203:
2202:
2201:
2199:
2193:
2190:2 H + 2 e ⇌ H
2189:
2184:
2180:
2176:
2171:
2167:
2163:
2158:
2154:
2150:
2131:
2127:
2125:
2122:
2121:
2093:
2089:
2080:
2077:
2076:
2059:
2055:
2053:
2050:
2049:
2047:
2023:
2009:
2007:
1991:
1987:
1975:
1971:
1964:
1957:
1953:
1941:
1937:
1930:
1928:
1924:
1908:
1899:
1894:
1881:
1877:
1868:
1864:
1862:
1859:
1858:
1838:
1834:
1832:
1829:
1828:
1827:relates pH and
1825:Nernst equation
1816:
1812:
1791:
1787:
1782:
1779:
1778:
1754:
1747:
1743:
1739:
1737:
1723:
1714:
1709:
1703:
1700:
1699:
1679:
1674:
1668:
1665:
1664:
1618:
1611:
1610:
1608:
1600:
1593:
1591:
1590:
1588:
1587:
1580:
1576:
1562:
1558:
1557:
1531:
1528:
1527:
1493:
1489:
1487:
1484:
1483:
1481:
1475:Nernst equation
1453:
1449:
1447:
1444:
1443:
1440:
1438:Nernst equation
1434:
1432:Nernst equation
1419:
1407:
1386:Sometimes when
1367:
1363:
1361:
1358:
1357:
1336:
1332:
1330:
1327:
1326:
1301:
1297:
1295:
1292:
1291:
1270:
1259:
1253:
1250:
1249:
1238:
1210:
1206:
1191:
1187:
1185:
1182:
1181:
1161:
1157:
1155:
1152:
1151:
1128:
1124:
1122:
1119:
1118:
1097:
1086:
1080:
1077:
1076:
1048:
1015:
1004:
998:
995:
994:
988:
970:
958:
954:
950:
936:
932:
922:
912:
907:
903:
893:
889:
881:
878:
877:
875:
865:
860:
856:
846:
841:
837:
827:
822:
812:
807:
797:
792:
783:
779:
774:
764:
759:
749:
744:
734:
730:
725:
721:
711:
706:
696:
691:
681:
676:
666:
661:
656:
650:
641:Oxidizing agent
624:
620:
567:
563:
546:
543:
542:
523:
520:
519:
502:
498:
496:
493:
492:
473:
470:
469:
449:
445:
422:
419:
418:
408:
400:
388:
384:
376:
373:thermal voltage
348:
346:
337:
333:
331:
328:
327:
307:
303:
297:
279:
275:
273:
258:
254:
253:
247:
243:
241:
230:
227:
226:
221:
212:
204:
193:
170:silver chloride
125:
91:
87:
85:
82:
81:
57:
53:
51:
48:
47:
33:(also known as
31:Redox potential
28:
23:
22:
18:Redox potential
15:
12:
11:
5:
3323:
3313:
3312:
3298:
3297:
3292:
3285:
3284:External links
3282:
3271:
3268:
3265:
3264:
3258:
3250:
3245:Half reactions
3237:
3231:
3222:Half reactions
3213:
3212:
3210:
3207:
3206:
3205:
3198:
3197:External links
3195:
3193:
3192:
3143:
3124:
3115:
3107:
3064:
3045:
3020:
3011:
3004:
2974:
2972:
2969:
2968:
2967:
2962:
2957:
2952:
2947:
2945:Redox gradient
2942:
2937:
2932:
2927:
2922:
2917:
2912:
2907:
2900:
2897:
2867:
2856:
2853:
2810:
2807:
2777:
2774:
2759:
2733:
2728:
2725:
2722:
2718:
2685:
2682:
2676:
2673:
2670:
2666:
2649:
2642:
2619:
2615:
2588:
2584:
2554:
2550:
2526:
2523:
2508:
2507:
2501:
2492:
2491:
2477:
2460:
2438:
2426:
2417:
2395:
2386:
2375:
2365:
2361:
2354:
2350:
2327:
2323:
2303:
2302:
2297:
2284:
2273:
2265:
2264:
2257:
2246:
2235:
2220:
2204:
2196:
2195:
2191:
2187:
2182:
2178:
2174:
2169:
2165:
2156:
2152:
2148:
2134:
2130:
2105:
2100:
2097:
2092:
2087:
2084:
2062:
2058:
2040:
2039:
2020:
2016:
2012:
2006:
2002:
1994:
1990:
1986:
1983:
1978:
1974:
1970:
1967:
1960:
1956:
1952:
1949:
1944:
1940:
1936:
1933:
1927:
1923:
1920:
1915:
1912:
1907:
1902:
1893:
1889:
1880:
1876:
1871:
1867:
1841:
1837:
1794:
1790:
1786:
1775:
1774:
1760:
1757:
1750:
1746:
1742:
1736:
1733:
1730:
1722:
1717:
1708:
1682:
1673:
1660:The half-cell
1658:
1657:
1646:
1642:
1639:
1636:
1632:
1621:
1614:
1603:
1596:
1583:
1579:
1574:
1571:
1565:
1555:
1552:
1549:
1545:
1542:
1539:
1535:
1496:
1492:
1456:
1452:
1436:Main article:
1433:
1430:
1417:
1405:
1370:
1366:
1339:
1335:
1304:
1300:
1273:
1268:
1265:
1262:
1258:
1237:
1234:
1219:
1216:
1213:
1209:
1205:
1202:
1197:
1194:
1190:
1167:
1164:
1160:
1137:
1134:
1131:
1127:
1100:
1095:
1092:
1089:
1085:
1018:
1013:
1010:
1007:
1003:
969:
966:
962:
961:
956:
952:
940:
939:
934:
919:
918:
915:
910:
905:
900:
899:
896:
891:
887:
872:
871:
868:
863:
858:
853:
852:
849:
844:
839:
834:
833:
830:
825:
819:
818:
815:
810:
804:
803:
800:
795:
789:
788:
785:
781:
777:
771:
770:
767:
762:
756:
755:
752:
747:
741:
740:
737:
732:
728:
723:
718:
717:
714:
709:
703:
702:
699:
694:
688:
687:
684:
679:
673:
672:
669:
664:
659:
653:
652:
651:Potential (V)
647:
646:Reducing agent
644:
642:
628:
622:
601:reducing agent
570:
566:
559:
556:
553:
550:
530:
527:
505:
501:
480:
477:
457:
452:
448:
444:
441:
438:
435:
432:
429:
426:
358:
354:
351:
345:
340:
336:
324:
323:
310:
306:
295:
292:
287:
282:
278:
272:
266:
261:
257:
250:
246:
240:
237:
234:
219:
203:The notion of
192:
189:
124:
121:
94:
90:
66:
63:
60:
56:
26:
9:
6:
4:
3:
2:
3322:
3311:
3308:
3307:
3305:
3296:
3293:
3291:
3288:
3287:
3281:
3278:
3246:
3241:
3223:
3218:
3214:
3204:
3201:
3200:
3188:
3184:
3179:
3174:
3170:
3166:
3163:(2): 255–61.
3162:
3158:
3154:
3147:
3141:
3137:
3131:
3129:
3121:
3111:
3103:
3099:
3095:
3091:
3087:
3083:
3079:
3075:
3068:
3060:
3056:
3049:
3034:
3030:
3024:
3015:
3007:
3001:
2997:
2990:
2988:
2986:
2984:
2982:
2980:
2975:
2966:
2963:
2961:
2958:
2956:
2953:
2951:
2948:
2946:
2943:
2941:
2938:
2936:
2933:
2931:
2928:
2926:
2925:Galvanic cell
2923:
2921:
2918:
2916:
2913:
2911:
2908:
2906:
2903:
2902:
2896:
2894:
2890:
2886:
2882:
2881:thermodynamic
2878:
2877:(solid) phase
2874:
2870:
2862:
2852:
2850:
2846:
2842:
2838:
2833:
2831:
2830:
2825:
2824:
2819:
2818:
2809:Water quality
2806:
2802:
2798:
2796:
2791:
2789:
2783:
2773:
2769:
2751:
2731:
2726:
2723:
2720:
2716:
2704:
2683:
2680:
2674:
2671:
2668:
2664:
2654:
2652:
2645:
2637:
2635:
2617:
2613:
2604:
2586:
2582:
2573:
2568:
2552:
2548:
2538:
2532:
2522:
2518:
2514:
2504:
2497:
2496:
2495:
2489:
2451:
2410:
2409:
2408:
2406:
2346:
2341:
2325:
2321:
2310:
2308:
2267:
2266:
2229:
2228:
2227:
2224:
2215:
2188:
2175:
2162:
2161:
2160:
2132:
2128:
2118:
2103:
2098:
2095:
2090:
2085:
2082:
2060:
2056:
2045:
2018:
2014:
2010:
2004:
2000:
1992:
1984:
1976:
1968:
1958:
1950:
1942:
1934:
1925:
1921:
1918:
1913:
1910:
1905:
1900:
1891:
1887:
1878:
1874:
1869:
1865:
1857:
1856:
1855:
1839:
1835:
1826:
1822:
1810:
1792:
1788:
1758:
1755:
1748:
1744:
1734:
1731:
1715:
1706:
1698:
1697:
1696:
1680:
1671:
1663:
1644:
1640:
1637:
1634:
1630:
1612:
1601:
1581:
1577:
1572:
1569:
1563:
1553:
1550:
1547:
1543:
1540:
1537:
1533:
1526:
1525:
1524:
1522:
1518:
1512:
1494:
1490:
1480:
1476:
1472:
1454:
1450:
1439:
1429:
1425:
1421:
1416:
1412:
1408:
1401:
1397:
1393:
1389:
1384:
1368:
1364:
1355:
1337:
1333:
1324:
1320:
1302:
1298:
1287:
1271:
1266:
1263:
1260:
1256:
1247:
1244:of different
1243:
1240:The relative
1233:
1217:
1214:
1211:
1207:
1203:
1200:
1195:
1192:
1188:
1165:
1162:
1158:
1135:
1132:
1129:
1125:
1116:
1098:
1093:
1090:
1087:
1083:
1074:
1070:
1066:
1062:
1058:
1054:
1046:
1042:
1038:
1034:
1016:
1011:
1008:
1005:
1001:
993:
987:
983:
979:
975:
965:
949:
948:
947:
945:
931:
930:
929:
927:
916:
911:
902:
901:
897:
888:
874:
873:
869:
864:
855:
854:
850:
845:
836:
835:
831:
826:
821:
820:
816:
811:
806:
805:
801:
796:
791:
790:
786:
778:
773:
772:
768:
763:
758:
757:
753:
748:
743:
742:
738:
729:
720:
719:
715:
710:
705:
704:
700:
695:
690:
689:
685:
680:
675:
674:
670:
665:
655:
654:
648:
645:
643:
640:
639:
635:
627:
618:
615:(Cu) ion and
614:
610:
606:
602:
598:
594:
589:
585:
568:
564:
557:
554:
551:
548:
528:
525:
503:
499:
478:
475:
450:
446:
439:
436:
433:
430:
427:
424:
415:
413:
406:
398:
394:
382:
374:
356:
352:
349:
343:
338:
334:
308:
304:
293:
290:
285:
280:
276:
270:
264:
259:
255:
248:
244:
238:
235:
232:
225:
224:
223:
218:
210:
207:is used with
201:
198:
188:
186:
182:
177:
175:
171:
167:
163:
159:
155:
151:
146:
144:
139:
134:
130:
120:
118:
114:
110:
92:
88:
79:
64:
61:
58:
54:
44:
40:
36:
32:
19:
3276:
3273:
3240:
3217:
3160:
3156:
3146:
3135:
3122:906, 98–109.
3119:
3110:
3077:
3073:
3067:
3054:
3048:
3036:. Retrieved
3032:
3023:
3014:
2995:
2865:
2864:
2841:chlorination
2834:
2827:
2821:
2815:
2812:
2803:
2799:
2792:
2785:
2700:
2655:
2647:
2640:
2638:
2569:
2534:
2525:Biochemistry
2516:
2512:
2509:
2499:
2493:
2449:
2369:·FeO with 2
2342:
2311:
2304:
2197:
2119:
2041:
1776:
1695:is given by
1659:
1520:
1441:
1426:
1422:
1388:electrolysis
1385:
1288:
1242:reactivities
1239:
989:
963:
941:
933:2 Li (s) + H
923:
611:(Cr) metal,
607:(Na) metal,
590:
586:
416:
411:
381:gas constant
325:
216:
202:
194:
178:
147:
132:
126:
46:
42:
38:
34:
30:
29:
2920:Fermi level
2889:dissolution
2396:2 (aq)
1402:to produce
1067:) for each
1051:) for each
1043:), a unity
885:+ 8 H + 5 e
726:O (l) + 2 e
191:Explanation
156:, although
143:salt bridge
3057:. London:
2971:References
2859:See also:
2823:Salmonella
2780:See also:
2766:= 1 M and
2529:See also:
2044:activities
1246:half cells
1236:Half cells
1063:of 1 atm (
972:See also:
735:(g) + 2 OH
185:titrations
3279:(7): 161.
2873:dissolved
2849:Minnesota
2732:⊖
2681:⊖
2634:nutrients
2603:anaerobes
2570:Strictly
2537:enzymatic
2459:⇌
2345:magnetite
2083:−
2005:−
1922:
1906:−
1901:⊖
1793:⊖
1785:Δ
1749:⊖
1741:Δ
1735:−
1716:⊖
1681:⊖
1620:⇀
1613:−
1602:−
1595:↽
1582:−
1517:half cell
1272:⊖
1204:−
1099:⊖
1065:1.013 bar
1017:⊖
775:2 H + 2 e
649:Reduction
451:−
440:
434:−
417:In fact,
265:λ
150:half cell
133:potential
113:electrons
3304:Category
3187:19320367
3102:93256604
3038:29 March
2899:See also
2829:Listeria
2684:′
1811:change,
1515:. For a
1057:reaction
1045:activity
1039:, or 77
890:Mn + 4 H
793:Sn + 2 e
760:Fe + 2 e
745:Cr + 3 e
707:Al + 3 e
692:Mg + 2 e
617:chloride
609:chromium
593:Reducers
162:graphite
154:platinum
131:, redox
3178:2646482
3082:Bibcode
2893:kinetic
2817:E. coli
2494:where:
2485:
2447:
2402:
2216:or one
2211:
2086:0.05916
2011:0.05916
1911:0.05916
1400:cathode
1180:, with
955:(g) + F
944:lithium
613:cuprous
409:
375:, with
371:is the
326:where,
286:0.05916
3185:
3175:
3100:
3002:
2839:(ppm)
2519:= −1/2
2380:and 1
2151:into H
2038:
1823:. The
1777:where
1354:oxygen
1073:metals
984:, and
917:+2.87
898:+1.49
870:+1.36
851:+1.07
832:+0.80
823:Ag + e
817:+0.16
808:Cu + e
802:+0.15
769:−0.44
754:−0.74
739:−0.83
716:−1.66
701:−2.38
686:−2.71
677:Na + e
671:−3.04
657:Li + e
605:sodium
561:
403:, the
397:Kelvin
391:, the
379:, the
299:×
294:16.903
3209:Notes
3098:S2CID
2940:Redox
2702:'
2535:Many
2181:+ 2 H
1725:volts
1513:plot)
1319:volts
1049:a = 1
908:+ 2 e
861:+ 2 e
842:+ 2 e
787:0.00
117:volts
80:, or
3183:PMID
3040:2018
3000:ISBN
2883:(at
2473:HFeO
2445:+ 2
2432:+ 2
2291:⇌ 2
2240:+ 2
1521:i.e.
1469:and
1442:The
1409:and
1406:2(g)
1396:NaCl
1150:and
1059:, a
990:The
866:2 Cl
847:2 Br
558:16.9
172:and
160:and
158:gold
3173:PMC
3165:doi
3161:124
3090:doi
2770:= 0
2760:gas
2567:).
1919:log
1896:red
1883:red
1819:is
1711:red
1676:red
1418:(s)
1069:gas
1053:ion
913:2 F
876:MnO
722:2 H
437:log
395:in
387:),
187:).
127:In
39:ORP
3306::
3247::
3224::
3181:.
3171:.
3159:.
3155:.
3127:^
3096:.
3088:.
3078:90
3076:.
3031:.
2978:^
2847:,
2826:,
2820:,
2772:.
2768:pH
2756:;
2483:+
2471:3
2413:Fe
2407::
2382:Fe
2371:Fe
2360:Fe
2358:≈
2349:Fe
2309:.
2293:OH
2278:+
2251:⇌
2159::
2025:pH
1854::
1511:pH
1509:–
1471:pH
1415:Na
1411:OH
1323:mV
1232:.
1041:°F
1037:°C
980:,
976:,
857:Cl
838:Br
828:Ag
813:Cu
798:Sn
765:Fe
750:Cr
712:Al
697:Mg
682:Na
667:Li
662:⇌
621:Cl
213:pe
211:.
205:pe
197:pH
145:.
45:,
43:pe
41:,
37:,
3259:2
3257:F
3251:2
3249:H
3232:2
3230:H
3189:.
3167::
3116:h
3104:.
3092::
3084::
3061:.
3042:.
3008:.
2868:h
2866:E
2758:P
2752:(
2746:)
2727:d
2724:e
2721:r
2717:E
2708:(
2675:d
2672:e
2669:r
2665:E
2650:h
2648:E
2643:h
2641:E
2618:h
2614:E
2587:h
2583:E
2553:h
2549:E
2540:(
2517:z
2515:/
2513:h
2502:h
2500:E
2488:H
2478:2
2450:e
2443:O
2439:2
2434:H
2427:4
2422:O
2418:3
2405:H
2366:3
2364:O
2362:2
2355:4
2353:O
2351:3
2347:(
2326:h
2322:E
2289:O
2285:2
2280:H
2269:O
2262:O
2258:2
2253:H
2242:H
2231:O
2223:O
2221:2
2219:H
2214:H
2200:O
2192:2
2183:2
2179:2
2177:O
2172:O
2170:2
2166:2
2164:O
2157:2
2153:2
2149:2
2133:h
2129:E
2104:)
2099:z
2096:h
2091:(
2061:h
2057:E
2019:z
2015:h
2001:)
1993:b
1989:}
1985:B
1982:{
1977:a
1973:}
1969:A
1966:{
1959:d
1955:}
1951:D
1948:{
1943:c
1939:}
1935:C
1932:{
1926:(
1914:z
1892:E
1888:=
1879:E
1875:=
1870:h
1866:E
1840:h
1836:E
1817:F
1813:z
1789:G
1759:F
1756:z
1745:G
1732:=
1729:)
1721:(
1707:E
1672:E
1645:D
1641:d
1638:+
1635:C
1631:c
1578:e
1573:z
1570:+
1564:+
1560:H
1554:h
1551:+
1548:B
1544:b
1541:+
1538:A
1534:a
1495:h
1491:E
1482:(
1455:h
1451:E
1404:H
1369:h
1365:E
1338:h
1334:E
1303:h
1299:E
1267:d
1264:e
1261:r
1257:E
1218:d
1215:e
1212:r
1208:E
1201:=
1196:x
1193:o
1189:E
1166:x
1163:o
1159:E
1136:d
1133:e
1130:r
1126:E
1094:d
1091:e
1088:r
1084:E
1047:(
1012:d
1009:e
1006:r
1002:E
957:2
953:2
951:H
935:2
906:2
904:F
894:O
892:2
882:4
879:−
859:2
840:2
782:2
780:H
733:2
731:H
724:2
634:v
623:2
569:h
565:E
555:=
552:e
549:p
529:e
526:p
504:h
500:E
479:e
476:p
456:]
447:e
443:[
431:=
428:e
425:p
412:e
401:F
389:T
383:(
377:R
357:F
353:T
350:R
344:=
339:T
335:V
309:H
305:E
291:=
281:H
277:E
271:=
260:T
256:V
249:H
245:E
239:=
236:e
233:p
220:H
217:E
93:h
89:E
65:d
62:e
59:r
55:E
20:)
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