Question

The standard EMF of a galvanic cell can be calculated from:

• A. the pH of the solution
• B. the size of the electrode
• C. the $E^o$ values of the half-cells
• D. the amount of metal in the anode

Answer 1

The correct option is C the $E^o$ values of the half-cells

The potential difference between the two electrodes is known as the cell potential. It is represented as $E_{cell}$ .

Cell potential of a galvanic cell at standard state is represented as $E_{cell}^{\circ }$

The standard cell potential ($\Delta E^o$) of a galvanic cell can be calculated by considering the standard reduction potentials of the two half cells $E^o$.
$E_{cell}^{\circ }=\text{SRP of substance reduced}-\text{SRP of substance oxidised}$
(SRP - Standard reduction potential)
$E_{cell}^{\circ }=E_{cathode\left(red\right)}^{\circ }-E_{anode\left(red\right)}^{\circ }$

or we can also write:
$E_{cell}^{\circ }=\text{SOP of substance oxidised}-\text{SOP of substance reduced}$
(SOP - Standard oxidation potential)
$E_{cell}^{\circ }=E_{anode\left(ox\right)}^{\circ }-E_{cathode\left(ox\right)}^{\circ }$

Hence, option D is correct.