16.10 Molten Lead(II) Chloride | @everexams study template

🔥 16.10 MOLTEN LEAD(II) CHLORIDE

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501°C Lead(II) chloride is solid at room temperature. To make it an electrolyte it must be heated up to 501°C to get molten lead chloride. Heat will render ions free to move and conduct electricity.

The molten lead is then taken in a heated crucible where its temperature is maintained above 500°C. Two inert electrodes (graphite or platinum) are then immersed in it.

Upon electrolysis the lead(II) ions will move towards the cathode where they are discharged forming lead in the liquid state. The chloride ions migrate towards the anode where they lose electrons to give chlorine gas. The electrolysis must be carried out at the temperature above the melting point of lead chloride.

Molten PbCl₂ >500°C graphite platinum Anode Cathode Pb²⁺ Cl⁻ Cl⁻ Cl₂ Pb
Figure 16.10: Molten PbCl₂ electrolysis – Pb at cathode, Cl₂ at anode

Reactions

Cathode (reduction): Pb²⁺ + 2e⁻ → Pb(l)

Anode (oxidation): 2Cl⁻ → Cl₂(g) + 2e⁻

Overall: PbCl₂(l) → Pb(l) + Cl₂(g)

KEYNOTE: Molten PbCl₂ – simple case: only Pb²⁺ and Cl⁻ present. No water interference.

TRICK: “Hot molten salt, ions move fast – Pb sinks as liquid, Cl₂ bubbles off.”

MEMORIZE: Inert electrodes (graphite/Pt) needed to avoid reaction with Cl₂.

Temperature must stay >501°C to keep PbCl₂ molten.

Way to remember: Cathode: “Cation gains, lead rains”; Anode: “Anion loses, chlorine gas oozes”.

10 MCQs • molten PbCl₂

📘 student guidelines

• Melting PbCl₂ requires >501°C – ions become free.
• Inert electrodes (graphite/platinum) prevent chlorine attack.
• Cathode: Pb²⁺ + 2e⁻ → Pb(l) (reduction). Anode: 2Cl⁻ → Cl₂(g) + 2e⁻ (oxidation).
• Overall: PbCl₂(l) → Pb(l) + Cl₂(g). No water means no competing H⁺/OH⁻.
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