Question

For a voltaic (or galvanic) cell using Ag, Ag⁺ (1.0M) and Zn Zn²⁺ (1.0 M) half-cells, which of the following statements is incorrect? 

(a) The zinc electrode is the anode. 

(b) Electrons will flow through the external circuit from the zinc electrode to the silver electrode. 

(c) The mass of the zinc electrode will decrease as the cell operates. 

(d) The concentration of Ag will decrease as the cell operates. 

(e) Reduction occurs at the zinc electrode as the cell operates.

Answer 1

In Ag-Zn voltaic cell, Zn is the anode and Ag is the cathode.

The following oxidation reaction takes place at anode:

$Zn(s)\rightarrow Zn^{2+}(aq)+2e^-$

Therefore the mass of Zn decreases as the cell operates, since Zn is being converted to Zn²⁺.

The following reduction reaction takes place at cathode:

$2Ag^{+}(aq)+2e^-\rightarrow 2Ag(s)$

Therefore the concentration of Ag⁺ decreases as the cell operates, since Ag⁺ is being converted to Ag.

The electron flow is from anode to cathode, that is, from zinc electrode to the silver electrode.

Therefore the incorrect statement is (e) since the oxidation occurs at zinc electrode.

Therefore the correct answer is option (e).