Balance each of the following oxidation-reduction reactions. For each, indicate which substance is being oxidized and which is being reduced.
a. $\mathrm{Co}(s)+\mathrm{Br}_2(l) \rightarrow \mathrm{CoBr}_3(s)$

Complete and balance the following half-reactions. In each case indicate whether the half- reaction is an oxidation or a reduction.

$$\mathrm { O } _ { 2 } ( g ) \longrightarrow \mathrm { H } _ { 2 } \mathrm { O } ( l )$$

(basic solution)

In the following reactions, identify which element is being oxidized and which is being reduced by assigning oxidation states.

a. $2\mathrm{Cu}(s)+\mathrm{S}(s) \rightarrow\mathrm{Cu}_2\mathrm{S}(s)$

The table of standard reduction potential of substances lists common metals in order of increasing reduction potential and decreasing oxidation potential. Which metal will most easily corrode?
a ) Li b) A1 c) Cu d) Au

Balance the equation for each of the following oxidation–reduction chemical reactions.

b. $\text{Fe}(s) + \text{H}_2\text{SO}_4(aq) \rightarrow \text{FeSO}_4(aq) + \text{H}_2(g)$

What is the oxidation state of the halogen in each of the following? (a) $\mathrm{H}_{5} \mathrm{IO}_{6}$ (b) $\mathrm{IO}_{4}^−$ (c) $\mathrm{ClO}_{2}$ (d) $\mathrm{ICl}_{3}$ (e) $\mathrm{F}_{2}$

Silver can be separated from gold because silver dissolves in nitric acid while gold does not. Is the dissolution of silver in nitric acid an acid-base reaction or an oxidation-reduction reaction? Explain your answer.

Balance the following oxidation–reduction reactions that occur in basic solution using the half-reaction method. $\mathrm{Mg}(s)+\mathrm{OCl}^{-}(a q) \rightarrow \mathrm{Mg}(\mathrm{OH})_{2}(s)+\mathrm{Cl}^{-}(a q)$

For the following oxidation-reduction reactions of metals with nonmetals, identify which element is being oxidized and which is being reduced.

a. $\mathrm{Cl}_2(\mathrm{~g})+\mathrm{Cu}(s) \rightarrow \mathrm{CuCl}_2(s)$

Complete and balance the following half-reactions. In each case indicate whether the half- reaction is an oxidation or a reduction.

$$\mathrm { O } _ { 2 } ( g ) \longrightarrow \mathrm { H } _ { 2 } \mathrm { O } ( l )$$

(acidic solution)

In the below reaction, identify which element is oxidized and which is reduced by assigning oxidation numbers.

$$\text{$2 \mathrm{KBr}(a q)+\mathrm{Cl}_2(g) \rightarrow 2 \mathrm{KCl}(a q)+\mathrm{Br}_2(l)$}$$

How is Acidithiobacillus ferrooxidans useful in the mining of copper ores? Which crucial step in the indirect oxidation of copper ores is carried out by A. ferrooxidans? How is copper recovered from copper solutions produced by leaching? (Section 21.1)

Balance the following oxidation-reduction reactions, which occur in basic solution, using the half-reaction method. $\mathrm { NO } _ { 2 } ^ { - } ( a q ) + \mathrm { Al } ( s ) \longrightarrow \mathrm { NH } _ { 3 } ( g ) + \mathrm { AlO } _ { 2 } ^ { - } ( a q )$

For the below oxidation-reduction reaction of metals with nonmetals, identify which element is oxidized and which is reduced :

$$\text{$\mathrm{H}_2(g)+\mathrm{S}(s) \rightarrow \mathrm{H}_2 \mathrm{~S}(g)$}$$