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Indian Forest Service (Mains)

Chemistry optional

  • 2 papers
  • 200 marks each
  • 3 h per paper

Paper I covers physical and inorganic chemistry.

Indian Forest Service (Mains), Chemistry optional · 2022 · Paper I

Q4(c)(ii). pH from a quinhydrone cell

Question

The EMF of a cell set up using hydrochloric acid solution, a standard calomel electrode and a quinhydrone electrode was found to be 0.1595 V at 25 °C. Calculate the pH of the hydrochloric acid solution. (Given the electrode potential of the calomel electrode = 0.244 V, and that of the quinhydrone electrode = 0.699 V.)

Answer in brief

Taking the quinhydrone electrode as the positive electrode, the solution has pH ≈ 5.00.

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Coversquinhydrone electrodecalomel electrodepH measurementNernst equationEMF

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