17.2 Galvanic cells  (Page 4/12)

Write the following balanced reactions using cell notation. Use platinum as an inert electrode, if needed.

(a) $\text{Mg}(s)+{\text{Ni}}^{\mathrm{2+}}(aq)⟶{\text{Mg}}^{\mathrm{2+}}(aq)+\text{Ni}(s)$

(b) $2{\text{Ag}}^{\text{+}}(aq)+\text{Cu}(s)⟶{\text{Cu}}^{\mathrm{2+}}(aq)+\text{2Ag}(s)$

(c) $\text{Mn}(s)+{\text{Sn(NO}}_3{)}_2(aq)⟶{\text{Mn(NO}}_3{)}_2(aq)+\text{Au}(s)$

(d) $3{\text{CuNO}}_3(aq)+{\text{Au(NO}}_3{)}_3(aq)⟶{\text{3Cu(NO}}_3{)}_2(aq)+\text{Au}(s)$

Given the following cell notations, determine the species oxidized, species reduced, and the oxidizing agent and reducing agent, without writing the balanced reactions.

(a) $\text{Mg}(s)│{\text{Mg}}^{\mathrm{2+}}(aq)║{\text{Cu}}^{\mathrm{2+}}(aq)│\text{Cu}(s)$

(b) $\text{Ni}(s)│{\text{Ni}}^{\mathrm{2+}}(aq)║{\text{Ag}}^{\text{+}}(aq)│\text{Ag}(s)$

For the cell notations in the previous problem, write the corresponding balanced reactions.

Balance the following reactions and write the reactions using cell notation. Ignore any inert electrodes, as they are never part of the half-reactions.

(a) $\text{Al}(s)+{\text{Zr}}^{\mathrm{4+}}(aq)⟶{\text{Al}}^{\mathrm{3+}}(aq)+\text{Zr}(s)$

(b) ${\text{Ag}}^{\text{+}}(aq)+\text{NO}(g)⟶\text{Ag}(s)+{\text{NO}}_3{}^{\text{−}}(aq)(\text{acidic solution})$

(c) ${\text{SiO}}_3{}^{\mathrm{2-}}(aq)+\text{Mg}(s)⟶\text{Si}(s)+\text{Mg}{\left(\text{OH}\right)}_2(s)\text{(basic solution)}$

(d) ${\text{ClO}}_3{}^{\text{−}}(aq)+{\text{MnO}}_2(s)⟶{\text{Cl}}^{\text{−}}(aq)+{\text{MnO}}_4{}^{\text{−}}(aq)\text{(basic solution)}$

Identify the species oxidized, species reduced, and the oxidizing agent and reducing agent for all the reactions in the previous problem.

From the information provided, use cell notation to describe the following systems:

(a) In one half-cell, a solution of Pt(NO ₃ ) ₂ forms Pt metal, while in the other half-cell, Cu metal goes into a Cu(NO ₃ ) ₂ solution with all solute concentrations 1 M .

(b) The cathode consists of a gold electrode in a 0.55 M Au(NO ₃ ) ₃ solution and the anode is a magnesium electrode in 0.75 M Mg(NO ₃ ) ₂ solution.

(c) One half-cell consists of a silver electrode in a 1 M AgNO ₃ solution, and in the other half-cell, a copper electrode in 1 M Cu(NO ₃ ) ₂ is oxidized.

Why is a salt bridge necessary in galvanic cells like the one in [link] ?

An active (metal) electrode was found to gain mass as the oxidation-reduction reaction was allowed to proceed. Was the electrode part of the anode or cathode? Explain.

An active (metal) electrode was found to lose mass as the oxidation-reduction reaction was allowed to proceed. Was the electrode part of the anode or cathode? Explain.

The mass of three different metal electrodes, each from a different galvanic cell, were determined before and after the current generated by the oxidation-reduction reaction in each cell was allowed to flow for a few minutes. The first metal electrode, given the label A, was found to have increased in mass; the second metal electrode, given the label B, did not change in mass; and the third metal electrode, given the label C, was found to have lost mass. Make an educated guess as to which electrodes were active and which were inert electrodes, and which were anode(s) and which were the cathode(s).