Problem 44
As \(\mathrm{K}_{2} \mathrm{O}\) dissolves in water, the oxide ion reacts with water molecules to form hydroxide ions. Write the molecular and net ionic equations for this reaction. Based on the definitions of acid and base, what ion is the base in this reaction? What is the acid? What is the spectator ion in the reaction?
Problem 45
Define oxidation and reduction in terms of (a) electron transfer and (b) oxidation numbers.
Problem 46
Can oxidation occur without accompanying reduction? Explain.
Problem 49
Determine the oxidation number for the indicated element in each of the following substances: (a) \(\mathrm{S}\) in \(\mathrm{SO}_{2}\), (b) \(\mathrm{C}\) in \(\mathrm{COCl}_{2},(\mathrm{c}) \mathrm{Mn}\) in \(\mathrm{MnO}_{4}^{-}\), (d) \(\mathrm{Br}\) in \(\mathrm{HBrO}\), (e) \(\mathrm{As}\) in \(\mathrm{As}_{4}\), (f) \(\mathrm{O}\) in \(\mathrm{K}_{2} \mathrm{O}_{2}\).
Problem 50
Determine the oxidation number for the indicated element in each of the following compounds: (a) Ti in \(\mathrm{TiO}_{2}\) (b) Sn in \(\mathrm{SnCl}_{3}^{-}\), (c) \(\mathrm{C}\) in \(\mathrm{C}_{2} \mathrm{O}_{4}{ }^{2-}\), (d) \(\mathrm{N}\) in \(\mathrm{N}_{2} \mathrm{H}_{4}\), (e) \(\mathrm{N}\) in \(\mathrm{HNO}_{2}\), (f) \(\mathrm{Cr}\) in \(\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}\)
Problem 51
Which element is oxidized and which is reduced in the following reactions? (a) \(\mathrm{N}_{2}(g)+3 \mathrm{H}_{2}(g) \longrightarrow 2 \mathrm{NH}_{3}(g)\) (b) \(3 \mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{2}(a q)+2 \mathrm{Al}(s) \longrightarrow\) \(3 \mathrm{Fe}(s)+2 \mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}(a q)\) (c) \(\mathrm{Cl}_{2}(a q)+2 \mathrm{NaI}(a q) \longrightarrow \mathrm{I}_{2}(a q)+2 \mathrm{NaCl}(a q)\) (d) \(\mathrm{PbS}(s)+4 \mathrm{H}_{2} \mathrm{O}_{2}(a q) \longrightarrow \mathrm{PbSO}_{4}(s)+4 \mathrm{H}_{2} \mathrm{O}(l)\)
Problem 52
Which of the following are redox reactions? For those that are, indicate which element is oxidized and which is reduced. For those that are not, indicate whether they are precipitation or acid-base reactions. (a) \(\mathrm{Cu}(\mathrm{OH})_{2}(s)+2 \mathrm{HNO}_{3}(a q) \longrightarrow\) \(\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}(a q)+2 \mathrm{H}_{2} \mathrm{O}(I)\) (b) \(\mathrm{Fe}_{2} \mathrm{O}_{3}(s)+3 \mathrm{CO}(g) \longrightarrow 2 \mathrm{Fe}(s)+3 \mathrm{CO}_{2}(g)\) (c) \(\mathrm{Sr}\left(\mathrm{NO}_{3}\right)_{2}(a q)+\mathrm{H}_{2} \mathrm{SO}_{4}(a q) \longrightarrow\) (d) \(\mathrm{SrSO}_{4}(\mathrm{~s})+2 \mathrm{HNO}_{3}(a q)\) \(\mathrm{Zn}(s)+10 \mathrm{H}^{+}(a q)+2 \mathrm{NO}_{3}^{-}(a q) \longrightarrow\) \(4 \mathrm{Zn}^{2+}(a q)+\mathrm{N}_{2} \mathrm{O}(g)+5 \mathrm{H}_{2} \mathrm{O}(l)\)
Problem 53
Write balanced molecular and net ionic equations for the reactions of (a) manganese with dilute sulfuric acid; (b) chromium with hydrobromic acid; (c) tin with hydrochloric acid; (d) aluminum with formic acid, \(\mathrm{HCOOH}\).
Problem 54
Write balanced molecular and net ionic equations for the reactions of (a) hydrochloric acid with nickel; (b) dilute sulfuric acid with iron; (c) hydrobromic acid with magnesium; (d) acetic acid, \(\mathrm{CH}_{3} \mathrm{COOH}\), with zinc.
Problem 55
Using the activity series(Table 4.5), write balanced chemical equations for the following reactions. If no reaction occurs, simply write NR. (a) Iron metal is added to a solution of copper(II) nitrate; (b) zinc metal is added to a solution of magnesium sulfate; (c) hydrobromic acid is added to tin metal; (d) hydrogen gas is bubbled through an aqueous solution of nickel(II) chloride; (e) aluminum metal is added to a solution of cobalt(II) sulfate.
