Chapter 18

Balance each of the following half-reactions, which take place in acidic solution. a. $\mathrm{HClO}(aq)\to {\mathrm{Cl}}^{-}(aq)$ b. $\mathrm{NO}(aq)\to {\mathrm{N}}_2\mathrm{O}(g)$ c. ${\mathrm{N}}_2\mathrm{O}(aq)\to {\mathrm{N}}_2(g)$ d. ${\mathrm{ClO}}_3^{-}(aq)\to {\mathrm{HClO}}_2(aq)$

Balance each of the following half-reactions, which take place in acidic solution. a. ${\mathrm{O}}_2(g)\to {\mathrm{H}}_2\mathrm{O}(l)$ $\mathrm{b}.{\mathrm{SO}}_4^{2-}(aq)\to {\mathrm{H}}_2{\mathrm{SO}}_3(aq)$ c. ${\mathrm{H}}_2{\mathrm{O}}_2(aq)\to {\mathrm{H}}_2\mathrm{O}(l)$ d. ${\mathrm{NO}}_2^{-}(aq)\to {\mathrm{NO}}_3^{-}(aq)$

Balance each of the following oxidation-reduction reactions, which take place in acidic solution, by using the "half-reaction" method. a. $\mathrm{Mg}(s)+{\mathrm{Hg}}^{2+}(aq)\to {\mathrm{Mg}}^{2+}(aq)+{\mathrm{Hg}}_2^{2+}(aq)$ b. ${\mathrm{NO}}_3^{-}(aq)+{\mathrm{Br}}^{-}(aq)\to \mathrm{NO}(g)+{\mathrm{Br}}_2(l)$ c. $\mathrm{Ni}(s)+{\mathrm{NO}}_3^{-}(aq)\to {\mathrm{Ni}}^{2+}(aq)+{\mathrm{NO}}_2(g)$ d. ${\mathrm{ClO}}_4^{-}(aq)+{\mathrm{Cl}}^{-}(aq)\to {\mathrm{ClO}}_3^{-}(aq)+{\mathrm{Cl}}_2(g)$

Balance each of the following oxidation-reduction reactions, which take place in acidic solution, by using the "half-reaction" method. a. $\mathrm{Al}(s)+{\mathrm{H}}^{+}(aq)\to {\mathrm{Al}}^{3+}(aq)+{\mathrm{H}}_2(g)$ b. ${\mathrm{S}}^{2-}(aq)+{\mathrm{NO}}_3^{-}(aq)\to \mathrm{S}(s)+\mathrm{NO}(g)$ c. ${\mathrm{I}}_2(aq)+{\mathrm{Cl}}_2(aq)\to {\mathrm{IO}}_3^{-}(aq)+\mathrm{HCl}(g)$ d. ${\mathrm{AsO}}_4^{-}(aq)+{\mathrm{S}}^{2-}(aq)\to {\mathrm{AsO}}_3^{-}(aq)+\mathrm{S}(s)$

Iodide ion, ${\mathrm{I}}^{-}$, is one of the most easily oxidized species. Balance each of the following oxidation-reduction reactions, which take place in acidic solution, by using the "half-reaction" method. a. ${\mathrm{IO}}_3^{-}(aq)+{\mathrm{I}}^{-}(aq)\to {\mathrm{I}}_2(aq)$ b. ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}(aq)+{\mathrm{I}}^{-}(aq)\to {\mathrm{Cr}}^{3+}(aq)+{\mathrm{I}}_2(aq)$ c. ${\mathrm{Cu}}^{2+}(aq)+{\mathrm{I}}^{-}(aq)\to \mathrm{CuI}(s)+{\mathrm{I}}_2(aq)$

Nitric acid is a very strong acid, but is also a very strong oxidizing agent, and generally behaves as the latter. It will dissolve many metals. Balance the following oxidation-reduction reactions of nitric acid. a. $\mathrm{Cu}(s)+{\mathrm{HNO}}_3(aq)\to {\mathrm{Cu}}^{2+}(aq)+{\mathrm{NO}}_2(g)$ b. $\mathrm{Mg}(s)+{\mathrm{HNO}}_3(aq)\to {\mathrm{Mg}}^{2+}(aq)+{\mathrm{H}}_2(g)$

Sketch a schematic representation of a typical galvanic cell, using a reaction of your choice. Indicate the direction of electron flow in your cell. How are the solutions placed in electrical contact to allow charge to balance between the chambers of the cell?

What is a salt bridge? Why is a salt bridge necessary in a galvanic cell? Can some other method be used in place of the salt bridge?

In which direction do electrons flow in a galvanic cell, from anode to cathode or vice versa?

What type of reaction takes place at the cathode in a galvanic cell? At the anode?