Question

Attemp A galvanic (voltaic) cell consists of an electrode composed of magnesium in a 1.0 M magnesium ion solution and another electrode composed of copper in a 1.0 M copper(II) ion solution, connected by a salt bridge. Calculate the standard potential for this cell at 25 °C. Refer to the list of standard reduction potentials. 2.9

Answer 1

Consider half reactions and their reduction potentials.

Mg ²⁺ (aq) + 2 e ^-  $\rightarrow$ Mg (s) E ⁰ red = - 2.360 V

Cu ²⁺ (aq) + 2 e ^-  $\rightarrow$ Cu (s) E ⁰ red = + 0.339 V

Significance of electrode potential is element having more positive value of reduction potential has more tendency to undergo reduction. Hence it acts as a cathode.

Element having less positive value of reduction potential has less tendency to undergo reduction , hence it acts as a anode.

From above reduction potential it is clear that , Cu will acts as a cathode & Mg will acts as a anode.

The standard emf of the cell is calculated as E ⁰ cell = E ⁰ cathode - E ⁰ anode

$\therefore$ E ⁰ cell = 0.339 V - ( - 2.360 V)

E ⁰ cell = 0.339 V + 2.360 V

E ⁰ cell = 2.699 V

ANSWER : E ⁰ cell = 2.699 V