3.293051e-4
g/C
1.185498
g/Ah
31.773
g/equiv
3,600
C
1
Ah
1.185498
g
0.01865575
mol
3.293051e-4
g/C
1.185498
g/Ah
31.773
g/equiv
3,600
C
1
Ah
1.185498
g
0.01865575
mol
The Electrochemical Equivalent Calculator computes the electrochemical equivalent (Z) of any element — the mass deposited per unit of electric charge passed through an electrolyte. This fundamental constant, expressed in g/C (grams per coulomb) or g/Ah (grams per ampere-hour), directly links the physical quantity of matter produced to the electrical charge consumed. The electrochemical equivalent depends only on the molar mass and valence of the deposited species. It is a key parameter in electroplating thickness calculations, battery capacity design, coulometric analysis, and industrial electrolysis optimization. By knowing Z, engineers can quickly determine how much material will be deposited for any given current and time without recalculating from Faraday's law each time.
The electrochemical equivalent is defined as:
$$Z = \frac{M}{nF}$$
where M is the molar mass (g/mol), n is the number of electrons transferred per ion (valence), and F = 96,485 C/mol is the Faraday constant.
Once Z is known, mass deposited is simply:
$$m = Z \times I \times t = Z \times Q$$
The equivalent mass (gram-equivalent weight) is:
$$E = \frac{M}{n}$$
This is related to Z by: Z = E/F. Converting to practical units:
$$Z_{g/Ah} = Z_{g/C} \times 3600$$
For example, copper (M = 63.546, n = 2) has Z = 63.546/(2 × 96485) = 3.294 × 10⁻⁴ g/C = 1.186 g/Ah. This means one ampere-hour deposits 1.186 grams of copper.
A larger Z value means more mass is deposited per unit charge. Elements with high molar mass and low valence have the highest electrochemical equivalents (e.g., silver: Z = 1.118 × 10⁻³ g/C). Elements with low molar mass and high valence have the lowest (e.g., aluminum: Z = 9.32 × 10⁻⁵ g/C). The g/Ah unit is more practical for industrial use since electroplating processes typically run for hours. Battery designers use Z to calculate how many grams of active material are needed for a given ampere-hour capacity.
Inputs
Results
Z = 63.546/(2 × 96485) = 3.294 × 10⁻⁴ g/C = 1.186 g/Ah. At 1 A for 1 hour, exactly 1.186 g of copper deposits. The equivalent mass is 31.773 g/equiv (mass per Faraday).
Inputs
Results
Z = 107.868/(1 × 96485) = 1.118 × 10⁻³ g/C = 4.025 g/Ah. Silver has one of the highest Z values due to high M and low n. At 0.5 A for 2 hours (1 Ah), 4.025 g deposits.
The electrochemical equivalent (Z) is the mass of a substance deposited or dissolved per unit of electric charge (coulomb). It is a characteristic constant for each element at a given valence state, calculated as Z = M/(nF).
The SI unit is g/C (grams per coulomb). Practical units include g/Ah (grams per ampere-hour) and mg/C. The g/Ah unit is 3600 times larger than g/C since 1 Ah = 3600 C.
Higher valence means more electrons are needed per ion, so less mass is deposited per coulomb. Fe²⁺ (Z = 2.89 × 10⁻⁴ g/C) deposits more mass per coulomb than Fe³⁺ (Z = 1.93 × 10⁻⁴ g/C) because the divalent form requires fewer electrons.
Z allows quick calculation of plating time: t = m/(Z × I). To deposit 10 g of chromium (Z = 8.99 × 10⁻⁵ g/C) at 50 A: t = 10/(8.99 × 10⁻⁵ × 50) = 2225 seconds ≈ 37 minutes (at 100% efficiency).
Z = E/F where E = M/n is the equivalent mass and F is the Faraday constant. The equivalent mass is the mass deposited per Faraday of charge (96,485 C), while Z is the mass per single coulomb.
Among common metals, gold (Au³⁺: Z = 6.81 × 10⁻⁴ g/C) and silver (Ag⁺: Z = 1.118 × 10⁻³ g/C) have high values. Silver's monovalent state gives it the highest Z among practical plating metals.
Battery capacity (Ah) = mass of active material / Z_g/Ah. For a lithium anode: Z = 0.259 g/Ah. To get 1 Ah capacity, you need 0.259 g of lithium (plus excess for practical reasons).
Yes, if the oxidation state changes. Iron can deposit as Fe²⁺ (n=2) or from Fe³⁺ (n=3), giving different Z values. The correct valence for the actual electrode reaction must be used.
Electrochemical equivalents were among the first evidence for quantized electric charge. Faraday's observation that equivalent masses are proportional to atomic weights divided by small integers supported the atomic theory and eventually led to the concept of the electron.
The theoretical Z from M/(nF) is exact for 100% current efficiency. Actual deposition may differ due to side reactions, hydrogen co-evolution, or dissolution of deposited material. Measured Z values are used to determine current efficiency.
Roboculator Team
The Roboculator Team explains calculations, planning tools, and practical formulas in clear language for real-life situations.
How helpful was this calculator?
Be the first to rate!
