91Ó°ÊÓ

Identify the oxidizing agent and the reducing agent in each of these redox equations. $$ \begin{array}{l}{\text { a. } \mathrm{N}_{2}+3 \mathrm{H}_{2} \rightarrow 2 \mathrm{NH}_{3}} \\ {\text { b. } 2 \mathrm{Na}+\mathrm{I}_{2} \rightarrow 2 \mathrm{NaI}}\end{array} $$

What is the reducing agent in this balanced equation? $$ \begin{array}{c}{8 \mathrm{H}^{+}+\mathrm{Sn}+6 \mathrm{Cl}^{-}+4 \mathrm{NO}_{3}^{-1} \rightarrow} \\ {\mathrm{SnCl}_{6}^{-2}+4 \mathrm{NO}_{2}+4 \mathrm{H}_{2} \mathrm{O}}\end{array} $$

What is the oxidation number of manganese in \(\mathrm{KMnO}_{4} ?\)

Determine the oxidation number of the boldface element in these substances and ions. a. \(\mathrm{CaCrO}_{4}\) b. \(\mathrm{NaHSO}_{4}\) c. \(\mathrm{NO}_{2}^{-}\) d. \(\mathrm{BrO}_{3}^{-}\)

Identify each of these half-reactions as either oxidation or reduction. $$ \begin{array}{l}{\text { a. } \mathrm{Al} \rightarrow \mathrm{Al}^{3+}+3 \mathrm{e}^{-}} \\ {\text { b. } \mathrm{Cu}^{2+}+\mathrm{e}^{-} \rightarrow \mathrm{Cu}^{+}}\end{array} $$

Which of these equations does not represent a redox reaction? Explain your answer. $$ \begin{array}{l}{\text { a. } \mathrm{LiOH}+\mathrm{HNO}_{3} \rightarrow \mathrm{LiNO}_{3}+\mathrm{H}_{2} \mathrm{O}} \\ {\text { b. } \mathrm{MgI}_{2}+\mathrm{Br}_{2} \rightarrow \mathrm{MgBr}_{2}+\mathrm{I}_{2}}\end{array} $$

Determine the oxidation number of nitrogen in each of these molecules or ions. $$ \text { a. }\mathrm{NO}_{3} \quad \text { b. } \mathrm{N}_{2} \mathrm{O} \quad \text { c. } \mathrm{NF}_{3} $$

Determine the oxidation number of each element in these compounds or ions. $$ \begin{array}{l}{\text { a. } \mathrm{Au}_{2}\left(\mathrm{SeO}_{4}\right)_{3} \text { (gold (III) selenate) }} \\ {\text { b. } \mathrm{Ni}(\mathrm{CN})_{2} \text { (nickel (II) cyanide) }}\end{array} $$

Explain how the sulfite ion \(\left(5 \mathrm{O}_{3}^{2-}\right)\) differs from sulfur trioxide \(\left(\mathrm{SO}_{3}\right),\) shown in Figure \(19.10 .\)

Compare and contrast balancing redox equations in acidic and basic solutions.