Chapter 16

Use the half-reaction method to balance each redox reaction occurring in acidic aqueous solution. (a) \(\mathrm{ClO}_{4}^{-}(a q)+\mathrm{Cl}^{-}(a q) \longrightarrow \mathrm{ClO}_{3}^{-}(a q)+\mathrm{Cl}_{2}(g)\) (b) \(\mathrm{MnO}_{4}^{-}(a q)+\mathrm{Al}(s) \longrightarrow \mathrm{Mn}^{2+}(a q)+\mathrm{Al}^{3+}(a q)\) (c) \(\mathrm{Br}_{2}(a q)+\mathrm{Sn}(s) \longrightarrow \mathrm{Sn}^{2+}(a q)+\mathrm{Br}^{-}(a q)\)

Use the half-reaction method to balance each redox reaction occurring in acidic aqueous solution. (a) \(\mathrm{IO}_{3}^{-}(a q)+\mathrm{SO}_{2}(g) \longrightarrow \mathrm{I}_{2}(s)+\mathrm{SO}_{4}{ }^{2-}(a q)\) (b) \(\mathrm{Sn}^{4+}(a q)+\mathrm{H}_{2}(g) \rightarrow \mathrm{Sn}^{2+}(a q)+\mathrm{H}^{+}(a q)\) (c) \(\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)+\mathrm{Br}^{-}(a q) \longrightarrow \mathrm{Cr}^{3+}(a q)+\mathrm{Br}_{2}(a q)\)

Balance each redox reaction occurring in basic solution. (a) \(\mathrm{NO}_{2}{ }^{-}(a q)+\mathrm{Al}(s) \longrightarrow \mathrm{NH}_{3}(g)+\mathrm{AlO}_{2}{ }^{-}(a q)\) (b) \(\mathrm{Al}(s)+\mathrm{MnO}_{4}^{-}(a q) \longrightarrow \mathrm{MnO}_{2}(s)+\mathrm{Al}(\mathrm{OH})_{4}^{-}(a q)\)

Which metal has the least tendency to be oxidized? (a) \(\mathrm{Ag}\) (b) \(\mathrm{Na}\) (c) \(\mathrm{Ni}\) (d) \(\mathrm{Pb}\)

Which metal has the least tendency to be oxidized? (a) Sn (b) \(\mathrm{Mg}\) (c) Cu (d) \(\mathrm{Fe}\)

Determine whether each redox reaction occurs spontaneously in the forward direction. (a) \(\mathrm{Ca}^{2+}(a q)+\mathrm{Zn}(s) \longrightarrow \mathrm{Ca}(s)+\mathrm{Zn}^{2+}(a q)\) (b) \(2 \mathrm{Ag}^{+}(a q)+\mathrm{Ni}(s) \longrightarrow 2 \mathrm{Ag}(s)+\mathrm{Ni}^{2+}(a q)\) (c) \(\mathrm{Fe}(s)+\mathrm{Mn}^{2+}(a q) \longrightarrow \mathrm{Fe}^{2+}(a q)+\mathrm{Mn}(s)\) (d) \(2 \mathrm{Al}(s)+3 \mathrm{~Pb}^{2+}(a q) \longrightarrow 2 \mathrm{Al}^{3+}(a q)+3 \mathrm{~Pb}(s)\)

Make a sketch of an electrochemical cell with the overall reaction shown here. Label the anode, the cathode, and the salt bridge. Indicate the direction of electron flow. Hint: When drawing electrochemical cells, the anode is usually drawn on the left side. $$ \mathrm{Mg}(s)+\mathrm{Ni}^{2+}(a q) \longrightarrow \mathrm{Mg}^{2+}(a q)+\mathrm{Ni}(s) $$

Make a sketch of an electrolysis cell that could be used to electroplate copper onto other metal surfaces. Label the anode and the cathode and show the reactions that occur at each.

Make a sketch of an electrolysis cell that could be used to electroplate nickel onto other metal surfaces. Label the anode and the cathode and show the reactions that occur at each.

Which metal, if coated onto iron, would prevent the corrosion of iron? (a) Zn (b) Sn (c) Mn