Electrochemical equivalent
The electrochemical equivalent (Ä e ) indicates how many grams of a substance are deposited during electrolysis on an electrode by an electrical charge of one coulomb (or one ampere hour ). It is equal to the molar mass M divided by the product of the change in the valency or the oxidation number z of the substance and the Faraday constant F:
The electrochemical equivalent is an important parameter in electroplating . For each single charge of one mole, 96485.336 As / mol (Faraday constant) are required for reduction or oxidation.
The charge actually required for the deposition is often greater than the value calculated with the aid of the electrochemical equivalent due to side reactions; this is then taken into account via the current yield.
background
According to Faraday's First Law in its original version, the mass of a substance deposited during electrolysis is proportional to the electrical charge that has flowed. The electrochemical equivalent is the proportionality factor between charge Q and deposited mass m :
The formula given above results from Faraday's second law, according to which the mass of the converted substance is proportional to its molar mass.
Table of values for electrochemical equivalents
The SI unit of the electrochemical equivalent is g / C or g / As. In electroplating, charges are usually measured in ampere hours (Ah); The unit g / Ah is therefore also used for Ä e .
element | OZ | Sb. |
Molar mass [g / mol] |
Change in value |
[µmol / As] |
Ä e [mg / As] |
Ä e [g / Ah] |
Type | Application examples, comments |
---|---|---|---|---|---|---|---|---|---|
aluminum | 13 | Al | 26.98154 | 3 | 3.45476 | 0.09321 | 0.33557 | M. | Aluminum production 3 ↔ 0 |
antimony | 51 | Sb | 121.76 | 3 | 3.45476 | 0.42065 | 1.51434 | SG | −3 ↔ 0 or 3 ↔ 0 |
antimony | 51 | Sb | 121.76 | 5 | 2.07285 | 0.25239 | 0.90861 | SG | 5 ↔ 0 |
antimony | 51 | Sb | 121.76 | 2 | 5.18213 | 0.63098 | 2.27152 | SG | 5 ↔ 3 |
barium | 56 | Ba | 137.327 | 2 | 5.18213 | 0.71165 | 2.56193 | EAM | 2 ↔ 0 |
beryllium | 4th | Be | 9.01218 | 2 | 5.18213 | 0.04670 | 0.16813 | EAM | 2 ↔ 0 |
Bismuth | 83 | Bi | 208.9804 | 3 | 3.45476 | 0.72198 | 2.59912 | SG | 3 ↔ 0 |
lead | 82 | Pb | 207.2 | 4th | 2.59107 | 0.53687 | 1.9327 | M. | 4 ↔ 0 |
lead | 82 | Pb | 207.2 | 2 | 5.18213 | 1.0737 | 3.8655 | M. | Lead battery 4 ↔ 2 or 2 ↔ 0 |
bromine | 35 | Br | 79.904 | 1 | 10.3643 | 0.82815 | 2.98133 | H | −1 ↔ 0 |
cadmium | 48 | CD | 112.414 | 2 | 5.18213 | 0.58254 | 2.09716 | M. | 2 ↔ 0 |
Cesium | 55 | Cs | 132.90545 | 1 | 10.3643 | 1.37747 | 4.95888 | AT THE | 1 ↔ 0 |
Calcium | 20th | Approx | 40.078 | 2 | 5.18213 | 0.20769 | 0.74768 | EAM | 2 ↔ 0 |
chlorine | 17th | Cl | 35.45 | 1 | 10.3643 | 0.3674 | 1.3227 | H | Chlor-alkali electrolysis −1 ↔ 0 |
chrome | 24 | Cr | 51.9961 | 3 | 3.45476 | 0.17963 | 0.64668 | M. | Chrome plating 3 ↔ 0 |
chrome | 24 | Cr | 51.9961 | 6th | 1.72738 | 0.08982 | 0.32334 | M. | Chrome plating 6 ↔ 0 |
Cobalt | 27 | Co | 58.93319 | 2 | 5.18213 | 0.30540 | 1.09944 | M. | 2 ↔ 0 |
iron | 26th | Fe | 55.845 | 2 | 5.18213 | 0.28940 | 1.04183 | M. | Iron coating 2 ↔ 0 |
iron | 26th | Fe | 55.845 | 3 | 3.45476 | 0.19293 | 0.69455 | M. | 3 ↔ 0 |
iron | 26th | Fe | 55.845 | 1 | 10.3643 | 0.57879 | 2.08365 | M. | 3 ↔ 2 |
fluorine | 9 | F. | 18.9984 | 1 | 10.3643 | 0.19690 | 0.70886 | H | Fluorine production −1 ↔ 0 |
gold | 79 | Au | 196.96657 | 1 | 10.3643 | 2.04141 | 7.34909 | M. | Au (I) only stable in complexes |
gold | 79 | Au | 196.96657 | 3 | 3.45476 | 0.68047 | 2.4497 | M. | 3 ↔ 0 |
Iodine | 53 | I. | 126.90447 | 1 | 10.3643 | 1.31527 | 4.73498 | H | −1 ↔ 0 |
potassium | 19th | K | 39.0983 | 1 | 10.3643 | 0.40523 | 1.45881 | AT THE | 1 ↔ 0 |
copper | 29 | Cu | 63,546 | 2 | 5.18213 | 0.32930 | 1.18549 | M. | Electrolytic copper refining 2 ↔ 0 |
copper | 29 | Cu | 63,546 | 1 | 10.3643 | 0.65861 | 2,37099 | M. | 1 ↔ 0 |
lithium | 3 | Li | 6.94 | 1 | 10.3643 | 0.0719 | 0.2589 | AT THE | Lithium production 1 ↔ 0 |
magnesium | 12 | Mg | 24.305 | 2 | 5.18213 | 0.12595 | 0.45343 | EAM | Magnesium production 2 ↔ 0 |
manganese | 25th | Mn | 54.93804 | 7th | 1.48061 | 0.08134 | 0.29283 | M. | 7 ↔ 0 |
manganese | 25th | Mn | 54.93804 | 2 | 5.18213 | 0.28470 | 1.02491 | M. | |
manganese | 25th | Mn | 54.93804 | 1 | 10.3643 | 0.56939 | 2.04981 | M. | Zinc-manganese cells 4 ↔ 3 or 3 ↔ 2 |
manganese | 25th | Mn | 54.93804 | 3 | 3.45476 | 0.18980 | 0.68327 | M. | |
sodium | 11 | N / A | 22.98977 | 1 | 10.3643 | 0.23827 | 0.85778 | AT THE | Sodium production 1 ↔ 0 |
nickel | 28 | Ni | 58.6934 | 2 | 5.18213 | 0.30416 | 1.09497 | M. | galvanic nickel plating 2 ↔ 0 |
niobium | 41 | Nb | 92.90637 | 5 | 2.07285 | 0.19258 | 0.69329 | M. | |
palladium | 46 | Pd | 106.42 | 2 | 5.18213 | 0.55148 | 1.98534 | M. | 2 ↔ 0 |
platinum | 78 | Pt | 195.084 | 4th | 2.59107 | 0.50548 | 1.81971 | M. | 4 ↔ 0 |
platinum | 78 | Pt | 195.084 | 2 | 5.18213 | 1.01095 | 3,63943 | M. | 4 ↔ 2 or 2 ↔ 0 |
mercury | 80 | Ed | 200.592 | 2 | 5.18213 | 1.03949 | 3.74218 | M. | |
mercury | 80 | Ed | 200.592 | 1 | 10.3643 | 2.07899 | 7,48436 | M. | |
Rhodium | 45 | Rh | 102.90549 | 3 | 3.45476 | 0.35551 | 1.27985 | M. | 3 ↔ 0 |
Rubidium | 37 | Rb | 85.4678 | 1 | 10.3643 | 0.88581 | 3.18892 | AT THE | 1 ↔ 0 |
oxygen | 8th | O | 15.9994 | 2 | 5.18213 | 0.08291 | 0.29848 | Ch | Water electrolysis −2 ↔ 0 |
sulfur | 16 | S. | 32.06 | 2 | 5.18213 | 0.1661 | 0.5981 | Ch | −2 ↔ 0 |
selenium | 34 | Se | 78.971 | 2 | 5.18213 | 0.40924 | 1.47326 | Ch | −2 ↔ 0 |
silver | 47 | Ag | 107.8682 | 1 | 10.3643 | 1.11798 | 4.02471 | M. | 1 ↔ 0 |
strontium | 38 | Sr | 87.62 | 2 | 5.18213 | 0.4541 | 1.6346 | EAM | 2 ↔ 0 |
Tantalum | 73 | Ta | 180.94788 | 5 | 2.07285 | 0.37508 | 1.35028 | M. | 5 ↔ 0 |
Thallium | 81 | Tl | 204,382 | 3 | 3.45476 | 0.70609 | 2.54192 | M. | 3 ↔ 0 |
Thallium | 81 | Tl | 204,382 | 1 | 10.3643 | 2.11827 | 7.62577 | M. | 1 ↔ 0 |
titanium | 22nd | Ti | 47.867 | 4th | 2.59107 | 0.12403 | 0.44650 | M. | 4 ↔ 0 |
Vanadium | 23 | V | 50.9415 | 5 | 2.07285 | 0.10559 | 0.38014 | M. | 5 ↔ 0 |
hydrogen | 1 | H | 1.0074 | 1 | 10.3643 | 0.01044 | 0.03759 | Hy | Water electrolysis |
tungsten | 74 | W. | 183.84 | 4th | 2.59107 | 0.47634 | 1.71483 | M. | 4 ↔ 0 |
zinc | 30th | Zn | 65.38 | 2 | 5.18213 | 0.3388 | 1.2197 | M. | galvanic zinc plating |
tin | 50 | Sn | 118.71 | 2 | 5.18213 | 0.61517 | 2.21462 | M. | galvanic tinning 4 ↔ 2 or 2 ↔ 0 |
tin | 50 | Sn | 118.71 | 4th | 2.59107 | 0.30759 | 1.10731 | M. | 4 ↔ 0 |
Zirconium | 40 | Zr | 91.224 | 4th | 2.59107 | 0.23637 | 0.85092 | M. | 4 ↔ 0 |
literature
- Werner John, Bernhard Gaida, Technical Mathematics for Electroplating, 9th Edition 2007, Eugen G. Leuze Verlag, Bad Saulgau, ISBN 978-3-87480-230-7
See also: equivalent number , valence (chemistry)