Question

There are three voltaic cells. In each voltaic cell one half-cell contains a 1.0 M Fe(NO3)2(aq) solution with an Fe electrode. The contents of the other half-cells are as follows:Cell 1: a 1.0 M CuCl2(aq) solution with a Cu electrodeCell 2: a 1.0 M NiCl2(aq) solution with a Ni electrodeCell 3: a 1.0 M ZnCl2(aq) solution with a Zn electrodeIn which voltaic cell(s) does iron act as the anode?a)Cell 1b)Cell 2c)Cell 3d)Cells 1 and 2e)All three cells

Answer 1

Answer:

d)Cells 1 and 2

Explanation:

In a voltaic cell, oxidation occurs at the anode and reduction occurs at the cathode. The half cell that function as anode or cathode in a voltaic cell depends strictly on the reduction potential of the metal ion/metal system in that half cell.

Examining the reduction potentials of the various metal ion/metal systems in the three half cells;

Cu= +0.34 V

Ni= -0.25 V

Zn= -0.76 V

Fe(Fe2+)= -0.44 V

Hence only Zn2+ has a more negative reduction potential than Fe2+. The more negative the reduction potential, the greater the tendency of the system to function as the anode. Thus iron half cell will function as anode in cells 1&2 as explained in the argument above.