CBSE Class 12 · 2017 · Redox Reactions and ElectrochemistryShort Answer

Write the name of the cell which is generally used in hearing aids. Write the reactions taking place at the anode and the cathode of this cell.

Answer: Mercury cell. Anode: Zn(Hg)+2OH⁻→ZnO+H₂O+2e⁻; cathode: HgO+H₂O+2e⁻→Hg+2OH⁻.

Solution

The mercury cell is used in hearing aids.
Anode:

Zn (Hg) + 2O H^{-} ⟶ ZnO (s) + H_{2} O + 2 e^{-}

Cathode:

HgO (s) + H_{2} O + 2 e^{-} ⟶ Hg (l) + 2O H^{-}

CBSE Class 12 Board · 2017 · Subjective