The cell notation of a standard galvanic (voltaic) cell containing an unknown metal Y is shown below - NSC Technical Sciences - Question 6 - 2022 - Paper 2

1. The concentration of the solutions is maintained at 1 mol/dm³.

2. The temperature is maintained at 25 °C or 298 K.

The oxidising agent in this cell is the copper (II) ions (Cu²+).

6.4.1 Anode: Negative polarity
6.4.2 Cathode: Positive polarity

To identify metal Y, we must use the Nernst equation and calculate the standard electrode potential (E°). Given the reading of 1.10 V, we can set up the equation:

$E_{cell} = E_{cathode} - E_{anode}$

From the standard reference, we find that:

• E° for Cu²+/Cu is +0.34 V and
• E° for Y/Y²+ is unknown.

Thus, to find E° for metal Y, we rearrange:

$E_{cell} = E_{Cu^{2+}/Cu} - E_{Y^{2+}/Y}$

1.10 V = 0.34 V - E°(Y/Y²+)

Rearranging gives:

$E°(Y/Y²+) = 0.34 V - 1.10 V = -0.76 V$

This suggests that Y is Zinc (Zn), as its E° is -0.76 V.