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:

{\ displaystyle {\ ddot {A}} _ {e} = {\ frac {M} {z \ cdot 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 :

{\ displaystyle m = {\ ddot {A}} _ {e} Q}

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 .

Selected examples of calculated electrochemical equivalents Ä _e
element	OZ	Sb.	Molar mass [g / mol]	${\ displaystyle z}$ Change in value	${\ displaystyle {\ frac {1} {z \ cdot F}}}$ [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

Electrochemical equivalent

background

Table of values ​​for electrochemical equivalents

literature

Table of values for electrochemical equivalents