JAMB Chemistry 1993 Question 24

Question 24

Electrolysis

Half-cell reactions and E° values:
Cu²⁺(aq) + 2e⁻ → Cu(s): +0.34 V
Fe²⁺(aq) + 2e⁻ → Fe(s): −0.44 V
Ba²⁺(aq) + 2e⁻ → Ba(s): −2.90 V
Zn²⁺(aq) + 2e⁻ → Zn(s): −0.76 V
From the data above, it can be deduced that the most powerful reducing agent of the four metals is

A.Cu
B.Fe
C.Ba
D.Zn

Show the answer and explanation

Answer: C (Ba)

Explanation

The metal with the most negative electrode potential loses electrons most readily, so it is the strongest reducing agent. Barium (−2.90 V) is the most negative.