QUESTION 30

1. Oxidation and Reduction

   An electrochemical cell was constructed using Ni²⁺/Ni and Gd³⁺/Gd couples.

   When the Ni electrode is connected to the positive (+) terminal of the voltmeter, the voltmeter shows the cell potential as +2.02 V.

   Given that the standard reduction potential for the Ni²⁺/Ni couple is -0.25 V at 25C, predict the standard reduction potential of the Gd³⁺/Gd couple under standard conditions.

QUESTION 29

1. Oxidation and Reduction

   Consider the redox reaction below.

   HClO_2(aq) + 3 H⁺_(aq) + 4 Es²⁺_(aq) Cl^-_(aq) + 2 H₂O_(l) + 4 Es³⁺_(aq)

   Is HClO₂ in the reaction above acting as an oxidising agent or a reducing agent? Explain your answer. (2 marks)