Electrochemical Reactions — Where Chemistry Meets Electricity

CO₂ + 2H⁺ + 2e⁻ → CO + H₂O

Electrochemical reduction of CO₂ at a metal cathode can selectively produce CO (on Au/Ag), formate (on Sn/Pb/Bi), or hydrocarbons (on …

2H₂O → 2H₂ + O₂

An electric current passed through water splits it into hydrogen gas at the cathode and oxygen gas at the anode. …

NaCl + 3H₂O → NaClO₃ + 3H₂

Electrolysis of hot NaCl solution without a membrane allows chlorine produced at the anode to react with hydroxide from the …

Cu (impure) → Cu²⁺ + 2e⁻ → Cu (pure)

Impure copper anodes (99.5%) dissolve electrochemically while pure copper (99.99%) deposits at the cathode from CuSO₄/H₂SO₄ electrolyte. Impurities either remain …

Zn + 2MnO₂ + H₂O → ZnO + 2MnOOH

Alkaline batteries use zinc powder anode and MnO₂ cathode in potassium hydroxide electrolyte, producing 1.5 V. They offer 4–9 times …

2Al + 3H₂O → Al₂O₃ + 6H⁺ + 6e⁻

Anodizing grows a thick, porous aluminum oxide layer on aluminum surfaces by making the aluminum the anode in an acid …

Zn → Zn²⁺ + 2e⁻

A zinc sacrificial anode is electrically connected to a steel structure. Since zinc has a more negative electrode potential (-0.76 …

2NaCl + 2H₂O → Cl₂ + 2NaOH + H₂

Electrolysis of concentrated brine (NaCl solution) produces three essential industrial chemicals simultaneously: chlorine gas at the anode, sodium hydroxide solution …

Cr³⁺ + 3e⁻ → Cr

Chromium plating deposits a thin layer of chromium from a chromic acid or trivalent chromium bath. Decorative chrome is only …

MH + NiOOH → M + Ni(OH)₂

NiMH batteries use a metal hydride anode (typically a rare earth/nickel alloy like AB₅ or AB₂) and nickel oxyhydroxide cathode …

2Na + 3S → Na₂S₃

Sodium-sulfur batteries operate at 300–350°C with molten sodium anode, molten sulfur cathode, and a solid beta-alumina ceramic electrolyte that conducts …

Zn + Cu²⁺ → Zn²⁺ + Cu

The Daniell cell consists of a zinc anode in ZnSO₄ solution and a copper cathode in CuSO₄ solution, connected by …

Cu²⁺ + 2e⁻ → Cu

Copper ions from a CuSO₄ solution are reduced at the cathode surface, depositing a thin layer of metallic copper. The …

LiC₆ + CoO₂ → C₆ + LiCoO₂

During discharge, lithium ions deintercalate from the graphite anode and intercalate into the cobalt oxide cathode through a non-aqueous electrolyte. …

2H₂ + O₂ → 2H₂O

In a proton exchange membrane (PEM) fuel cell, hydrogen is oxidized at the anode and oxygen is reduced at the …

Fe → Fe²⁺ + 2e⁻

Electrochemical machining dissolves metal from a workpiece (anode) in a controlled pattern using a shaped cathode tool and flowing electrolyte …

Ag⁺ + e⁻ → Ag

Silver ions from a silver cyanide or silver nitrate bath are reduced at the cathode, depositing a thin, bright layer …

2NaCl → 2Na + Cl₂

The Downs process electrolyzes molten NaCl at about 600°C (lowered from 801°C by adding CaCl₂) to produce sodium metal at …

H₂ + ½O₂ → H₂O

SOFCs operate at 600–1000°C using a solid ceramic oxide electrolyte that conducts O²⁻ ions. Oxygen is reduced at the cathode …

Zn + 2MnO₂ + 2NH₄Cl → ZnCl₂ + Mn₂O₃ + 2NH₃ + H₂O

The zinc-carbon cell uses a zinc casing as anode and a carbon rod surrounded by MnO₂ paste as cathode, with …

Pb + PbO₂ + 2H₂SO₄ → 2PbSO₄ + 2H₂O

During discharge, lead is oxidized to PbSO₄ at the anode while PbO₂ is reduced to PbSO₄ at the cathode, consuming …

2Al₂O₃ + 3C → 4Al + 3CO₂

Alumina (Al₂O₃) is dissolved in molten cryolite (Na₃AlF₆) at 960°C and electrolyzed using carbon anodes. Aluminum is deposited at the …

ZnSO₄ + H₂O → Zn + H₂SO₄ + ½O₂

Zinc electrowinning (electroextraction) deposits zinc metal from purified zinc sulfate solution onto aluminum cathodes. The cathode deposit is stripped every …

MnSO₄ + 2H₂O → MnO₂ + H₂SO₄ + H₂

Electrolytic manganese dioxide (EMD) is produced by electrolyzing manganese sulfate solution in sulfuric acid at 90–98°C. MnO₂ deposits on the …

LiFePO₄ ⇌ FePO₄ + Li⁺ + e⁻

LFP batteries use lithium iron phosphate cathode and graphite anode with a cell voltage of 3.2–3.3 V and energy density …