Electrolysis
Electrolysis uses electrical energy to drive non-spontaneous redox reactions. Faraday's laws relate charge passed to mass deposited—essential for electroplating, water splitting, and metal refining.
Why This Chemistry Calculation Matters
Why: Electrolysis powers electroplating, chlor-alkali industry, aluminum production, and hydrogen generation. Faraday's laws give quantitative predictions.
How: Q = I×t; moles e⁻ = Q/F; mass = (M×Q)/(n×F). Choose the unknown and solve.
- ●Silver plating: Ag⁺ + e⁻ → Ag (n=1). Copper: Cu²⁺ + 2e⁻ → Cu (n=2).
- ●Water splitting: 2H₂O → 2H₂ + O₂ requires ~1.23 V minimum.
- ●F = 96,485 C/mol. One Faraday deposits 1 mol of monovalent ions.
- ●Current efficiency < 100% in practice due to side reactions.
Electrolysis Examples
⚡ Silver Electroplating
Deposit 5g of silver using 2A current
🔩 Copper Refining
Calculate time to deposit 100g copper at 5A
🏭 Aluminum Production
Mass of aluminum from 1000A for 1 hour
⚗️ Hydrogen Production
Calculate hydrogen gas from water electrolysis
✨ Gold Electroplating
Thin gold layer - 0.1g at 0.5A
🔧 Zinc Galvanizing
Zinc coating calculation
🧪 Chlorine Production
Industrial chlorine from brine
⚙️ Nickel Plating
Nickel electroplating process
🔩 Chrome Plating
Chromium electroplating
🔋 Lead Battery
Lead deposition in battery
💨 Oxygen Production
Oxygen from water electrolysis
🥫 Tin Plating
Tin electroplating
⚒️ Iron Refining
Iron electrorefining
🔋 Cadmium Battery
Cadmium in Ni-Cd battery
🔌 Copper Wire Production
Copper deposition for wire
Calculate Electrolysis Parameters
⚠️For educational and informational purposes only. Verify with a qualified professional.
🔬 Chemistry Facts
m = (M × I × t) / (n × F) — Faraday's law for mass.
— IUPAC
1 F = 96,485 C deposits 1 mol e⁻ worth of product.
— Electrochemistry
Electroplating: control thickness via current and time.
— Industry
Water electrolysis: 2 mol e⁻ per mol H₂; 4 mol e⁻ per mol O₂.
— Faraday
Faraday's Laws of Electrolysis
Faraday's laws describe the quantitative relationship between the amount of substance deposited or dissolved during electrolysis and the quantity of electric charge passed through the electrolyte.
m = mass (g), M = molar mass (g/mol), I = current (A), t = time (s), n = electrons, F = 96,485 C/mol
Common Electrochemical Substances
| Substance | Formula | Molar Mass (g/mol) | Electrons | Half-Reaction | Common Use |
|---|---|---|---|---|---|
| Silver | ext{Ag} | 107.87 | 1 | Ag⁺ + e⁻ → Ag | Electroplating, jewelry |
| Copper | ext{Cu} | 63.55 | 2 | Cu²⁺ + 2e⁻ → Cu | Electroplating, electronics |
| Zinc | ext{Zn} | 65.38 | 2 | Zn²⁺ + 2e⁻ → Zn | Galvanizing, batteries |
| Aluminum | ext{Al} | 26.98 | 3 | Al³⁺ + 3e⁻ → Al | Metal production, aerospace |
| Nickel | ext{Ni} | 58.69 | 2 | Ni²⁺ + 2e⁻ → Ni | Electroplating, batteries |
| Chromium | ext{Cr} | 52 | 3 | Cr³⁺ + 3e⁻ → Cr | Chrome plating |
| Gold | ext{Au} | 196.97 | 1 | Au⁺ + e⁻ → Au | Jewelry, electronics |
| Hydrogen | H_{2} | 2.016 | 2 | 2H⁺ + 2e⁻ → H₂ | Fuel production |
| Oxygen | O_{2} | 32 | 4 | 2H₂O → O₂ + 4H⁺ + 4e⁻ | Water electrolysis |
| Chlorine | Cl_{2} | 70.9 | 2 | 2Cl⁻ → Cl₂ + 2e⁻ | Chlor-alkali industry |
| Lead | ext{Pb} | 207.2 | 2 | Pb²⁺ + 2e⁻ → Pb | Batteries, refining |
| Tin | ext{Sn} | 118.71 | 2 | Sn²⁺ + 2e⁻ → Sn | Tin plating |
| Iron | ext{Fe} | 55.85 | 2 | Fe²⁺ + 2e⁻ → Fe | Steel production |
| Cadmium | ext{Cd} | 112.41 | 2 | Cd²⁺ + 2e⁻ → Cd | Batteries, plating |
Key Concepts
Faraday's Constant
F = 96,485 C/mol represents the charge of one mole of electrons. This fundamental constant connects electrical charge to chemical amount.
Charge Calculation
Total charge Q = I × t (current × time). This determines how many electrons flow through the circuit.
Stoichiometry
The number of electrons (n) determines the stoichiometry. More electrons per ion means less mass deposited per mole of electrons.
How Does Electrolysis Work?
Electrolysis is the process of using electrical energy to drive a non-spontaneous chemical reaction. When current flows through an electrolyte, ions migrate to electrodes where they gain or lose electrons.
⚡ Step-by-Step Process
1. Charge Flow
Q = I × t
Total charge in Coulombs
Example: 2A × 3600s = 7200 C
2. Moles of Electrons
moles e⁻ = Q / F
7200 C / 96485 C/mol
= 0.0746 mol electrons
3. Moles of Substance
moles = moles e⁻ / n
For Cu²⁺ (n=2):
0.0746 / 2 = 0.0373 mol Cu
4. Mass Deposited
m = moles × M
0.0373 × 63.55
= 2.37 g Cu
When to Use This Calculator
Electrolysis calculations are essential for industrial processes, electroplating operations, metal refining, and electrochemical research.
Electroplating
Calculate coating thickness, deposition time, and current requirements for metal plating operations.
- Silver/gold jewelry plating
- Chrome automotive parts
- Zinc galvanizing
Metal Refining
Determine production rates and energy requirements for electrolytic metal extraction and purification.
- Aluminum production
- Copper electrorefining
- Zinc extraction
Water Electrolysis
Calculate hydrogen and oxygen production rates for fuel generation and industrial gas production.
- Hydrogen fuel production
- Oxygen generation
- Chlor-alkali process
Practical Electrolysis Examples
Example: Silver Electroplating
Given:
- Current: 2.0 A
- Time: 1 hour (3600 s)
- Silver: Ag⁺ + e⁻ → Ag (n=1)
- Molar mass: 107.87 g/mol
Solution:
Q = 2.0 × 3600 = 7200 C
moles e⁻ = 7200 / 96485 = 0.0746 mol
moles Ag = 0.0746 / 1 = 0.0746 mol
Mass = 0.0746 × 107.87 = 8.05 g
Example: Aluminum Production
Given:
- Current: 1000 A
- Time: 1 hour (3600 s)
- Aluminum: Al³⁺ + 3e⁻ → Al (n=3)
- Molar mass: 26.98 g/mol
Solution:
Q = 1000 × 3600 = 3,600,000 C
moles e⁻ = 3,600,000 / 96485 = 37.3 mol
moles Al = 37.3 / 3 = 12.4 mol
Mass = 12.4 × 26.98 = 335 g
Limitations and Considerations
⚠️ Real-World Factors
- • Current efficiency may be less than 100%
- • Side reactions can consume charge
- • Overpotential increases energy requirements
- • Concentration changes affect conductivity
- • Temperature affects reaction rates
✓ Assumptions Made
- • 100% current efficiency
- • No side reactions
- • Constant current throughout process
- • Ideal electrode behavior
- • Uniform current distribution