electrochemistry

What prevents NH3 gas pressure build-up and cell rupture in a Dry Cell?

NH3 generated at the cathode reacts with Zn²⁺ to form the coordination complex: [Zn(NH3)_4]^{2+}.

Why does Mercury Cell maintain a completely constant potential (1.35 V)?

The overall cell reaction involves NO ION IN SOLUTION whose concentration can change during its lifetime.

What are the exact electrolyte and equivalent mass parameters for a Lead Storage Battery?

• Electrolyte: 38% H2SO4 by mass | Density = 1.30 g/cm³ • Consumes 2 moles H2SO4 per 2e⁻ (2F) ⟹ Equivalent Mass = 98 g/eq.

What catalysts/electrolytes are used in fuel cells, and what is the efficiency?

• Electrolyte: Concentrated aqueous KOH or NaOH • Catalysts: Finely divided Pt or Pd embedded in porous carbon • Efficiency: ~70% (η = ΔG / ΔH × 100).

How do Conductivity (κ) and Molar Conductivity (Λm) change upon dilution?

• Conductivity (κ): DECREASES (fewer ions per unit volume). • Molar Conductivity (Λm): INCREASES (total volume with 1 mole increases).

What are the exact NCERT operational parameters for the Standard Hydrogen Electrode (SHE)?

• Pt foil coated with Platinum Black • [H^+] = 1 M | H2 gas pressure = 1 bar • Standard potential assigned as 0.00 V at ALL temperatures.