Mercury cell (button cell)मर्करी सेल (बटन सेल)Mercury cell (button cell)

NCERT Fig 2.9 · Class 12 Chemistry · Chapter 2 · interactive diagram

Parts and what they mean

• Zinc–mercury amalgam — anode (जिंक–मर्करी अमलगम — ऐनोड) — Anode: Zn(Hg) + 2OH⁻ → ZnO(s) + H₂O + 2e⁻. Zinc is the reducing agent.
• Paste of HgO and carbon — cathode (HgO और कार्बन का पेस्ट — कैथोड) — Cathode: HgO + H₂O + 2e⁻ → Hg(l) + 2OH⁻. Mercury(II) oxide is the oxidising agent.
• Electrolyte: paste of KOH and ZnO (विद्युत-अपघट्य: KOH और ZnO का पेस्ट) — Overall: Zn(Hg) + HgO(s) → ZnO(s) + Hg(l). No ion in solution changes concentration, so the potential stays ≈ 1.35 V throughout its life.
• Steel case (स्टील आवरण) — Holds the cell; used in hearing aids, watches and other low-current devices.
• Top cap (ऊपरी ढक्कन) — Contact for the anode.
• Insulation (विद्युतरोधी) — Separates the two terminals.

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 2.9. Report a mistake