Question

Aluminium displaces hydrogen from acids but copper does
not. A galvanic cell prepared by combining Cu / Cu²⁺ and
Al / Al³⁺ has an e.m.f. of 2.0 V at 298 K. If the potential of
copper electrode is + 0.34 V, that of aluminium is
(a) + 1.66 V (b) – 1.66 V
(c) + 2.34 V (d) – 2.3 V

Answer 1

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❤.option B is correct

Answer 2

The potential of Al electrode is (b) -1.66V

1. We know that, here, Ecell = ECu / Cu²⁺ - EAl / Al³⁺

2. Given that E cell = + 2.0 V and ECu / Cu²⁺ = + 0.34 V

3. Thus, EAl / Al³⁺ = ECu / Cu²⁺- E cell

= 0.34 - 2.0

= -1.66 V

4. Proper care must be taken regarding the sign of the emf value.