4.2 Classifying Chemical Reactions

Indicate what type, or types, of reaction each of the following represents:

(a) $\text{Ca} \left(s\right) + \text{Br}_{2} \left(l\right) \rightarrow \text{CaBr}_{2} \left(s\right)$

(b) $\text{Ca} (\text{OH})_{2} \left(a q\right) + 2 \text{HBr} \left(a q\right) \rightarrow \text{CaBr}_{2} \left(a q\right) + 2 \text{H}_{2} \text{O} \left(l\right)$

(c) $\text{C}_{6} \text{H}_{12} \left(l\right) + 9 \text{O}_{2} \left(g\right) \rightarrow 6 \text{CO}_{2} \left(g\right) + 6 \text{H}_{2} \text{O} \left(g\right)$

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.

Determine the oxidation states of the elements in the compounds listed. None of the oxygen-containing compounds are peroxides or superoxides.

(a) H₃PO₄

(b) Al(OH)₃

(c) SeO₂

(d) KNO₂

(e) In₂S₃

(f) P₄O₆

Classify the following as acid-base reactions or oxidation-reduction reactions:

(a) $\text{Na}_{2} \text{S} \left(a q\right) + 2 \text{HCl} \left(a q\right) \rightarrow 2 \text{NaCl} \left(a q\right) + \text{H}_{2} \text{S} \left(g\right)$

(b) $2 \text{Na} \left(s\right) + 2 \text{HCl} \left(a q\right) \rightarrow 2 \text{NaCl} \left(a q\right) + \text{H}_{2} \left(g\right)$

(c) $\text{Mg} \left(s\right) + \text{Cl}_{2} \left(g\right) \rightarrow \text{MgCl}_{2} \left(s\right)$

(d) $\text{MgO} \left(s\right) + 2 \text{HCl} \left(a q\right) \rightarrow \text{MgCl}_{2} \left(a q\right) + \text{H}_{2} \text{O} \left(l\right)$

(e) $\text{K}_{3} \text{P} \left(s\right) + 2 \text{O}_{2} \left(g\right) \rightarrow \text{K}_{3} \text{PO}_{4} \left(s\right)$

(f) $3 \text{KOH} \left(a q\right) + \text{H}_{3} \text{PO}_{4} \left(a q\right) \rightarrow \text{K}_{3} \text{PO}_{4} \left(a q\right) + 3 \text{H}_{2} \text{O} \left(l\right)$

Complete and balance the following acid-base equations:

(a) HCl gas reacts with solid Ca(OH)₂(s).

(b) A solution of Sr(OH)₂ is added to a solution of HNO₃.

Complete and balance the following oxidation-reduction reactions, which give the highest possible oxidation state for the oxidized atoms.

(a) $\text{Al} \left(s\right) + \text{F}_{2} \left(g\right) \rightarrow$

(b) $\text{Al} \left(s\right) + \text{CuBr}_{2} \left(a q\right) \rightarrow$ (single displacement)

(c) $\text{P}_{4} \left(s\right) + \text{O}_{2} \left(g\right) \rightarrow$

(d) $\text{Ca} \left(s\right) + \text{H}_{2} \text{O} \left(l\right) \rightarrow$ (products are a strong base and a diatomic gas)

Complete and balance the equations for the following acid-base neutralization reactions. If water is used as a solvent, write the reactants and products as aqueous ions. In some cases, there may be more than one correct answer, depending on the amounts of reactants used.

(a) $\text{Mg} (\text{OH})_{2} \left(s\right) + \text{HClO}_{4} \left(a q\right) \rightarrow$

(b) $\text{SO}_{3} \left(g\right) + \text{H}_{2} \text{O} \left(l\right) \rightarrow (\text{assume an excess of water and that the product dissolves})$

(c) $\text{SrO} \left(s\right) + \text{H}_{2} \text{SO}_{4} \left(l\right) \rightarrow$

The military has experimented with lasers that produce very intense light when fluorine combines explosively with hydrogen. What is the balanced equation for this reaction?

Great Lakes Chemical Company produces bromine, Br₂, from bromide salts such as NaBr, in Arkansas brine by treating the brine with chlorine gas. Write a balanced equation for the reaction of NaBr with Cl₂.

Lithium hydroxide may be used to absorb carbon dioxide in enclosed environments, such as manned spacecraft and submarines. Write an equation for the reaction that involves 2 mol of LiOH per 1 mol of CO₂. (Hint: Water is one of the products.)

Complete and balance the equations of the following reactions, each of which could be used to remove hydrogen sulfide from natural gas:

(a) $\text{Ca} \left(\text{OH}\right)_{2} \left(s\right) + \text{H}_{2} \text{S} \left(g\right) \rightarrow$

(b) $\text{Na}_{2} \text{CO}_{3} \left(a q\right) + \text{H}_{2} \text{S} \left(g\right) \rightarrow$

Write balanced chemical equations for the reactions used to prepare each of the following compounds from the given starting material(s). In some cases, additional reactants may be required.

(a) solid ammonium nitrate from gaseous molecular nitrogen via a two-step process (first reduce the nitrogen to ammonia, then neutralize the ammonia with an appropriate acid)

(b) gaseous hydrogen bromide from l…

Complete and balance each of the following half-reactions (steps 2–5 in half-reaction method):

(a) $\text{Sn}^{4+} \left(a q\right) \rightarrow \text{Sn}^{2+} \left(a q\right)$

(b) $\left[\text{Ag} \left(\text{NH}_{3}\right)_{2}\right]^{+} \left(a q\right) \rightarrow \text{Ag} \left(s\right) + \text{NH}_{3} \left(a q\right)$

(c) $\text{Hg}_{2} \text{Cl}_{2} \left(s\right) \rightarrow \text{Hg} \left(l\right) + \text{Cl}^{−} \left(a q\right)$

(d) $\text{H}_{2} \text{O} \left(l\right) \rightarrow \text{O}_{2} \left(g\right)$ (in acidic solution)

(e) $\text{IO}_{3} ^{−} \left(a q\right) \rightarrow \text{I}_{2} \left(s\right)$ (in basic solution)

(f) $\text{SO}_{3} ^{2−} \left(a q\right) \rightarrow \text{SO}_{4} ^{2−} \left(a q\right)$ (in acidic solution)

(g) $\text{MnO}_{4} ^{−} \left(a q\right) \rightarrow \text{Mn}^{2+} \left(a q\right)$ (in acidic solution)

(h) $\text{Cl}^{−} \left(a q\right) \rightarrow \text{ClO}_{3} ^{−} \left(a q\right)$ (in basic solution)

Balance each of the following equations according to the half-reaction method:

(a) $\text{Sn}^{2+} \left(a q\right) + \text{Cu}^{2+} \left(a q\right) \rightarrow \text{Sn}^{4+} \left(a q\right) + \text{Cu}^{+} \left(a q\right)$

(b) $\text{H}_{2} \text{S} \left(g\right) + \text{Hg}_{2} ^{2+} \left(a q\right) \rightarrow \text{H} g \left(l\right) + \text{S} \left(s\right) (\text{in acid})$

(c) $\text{CN}^{−} \left(a q\right) + \text{ClO}_{2} \left(a q\right) \rightarrow \text{CNO}^{−} \left(a q\right) + \text{Cl}^{−} \left(a q\right) (\text{in acid})$

(d) $\text{Fe}^{2+} \left(a q\right) + \text{Ce}^{4+} \left(a q\right) \rightarrow \text{Fe}^{3+} \left(a q\right) + \text{Ce}^{3+} \left(a q\right)$

(e) $\text{HBrO} \left(a q\right) \rightarrow \text{Br}^{−} \left(a q\right) + \text{O}_{2} \left(g\right) (\text{in acid})$

Balance each of the following equations according to the half-reaction method:

(a) $\text{MnO}_{4} ^{−} \left(a q\right) + \text{NO}_{2} ^{−} \left(a q\right) \rightarrow \text{MnO}_{2} \left(s\right) + \text{NO}_{3} ^{−} \left(a q\right) (\text{in base})$

(b) $\text{MnO}_{4} ^{2−} \left(a q\right) \rightarrow \text{MnO}_{4} ^{−} \left(a q\right) + \text{MnO}_{2} \left(s\right) (\text{in base})$

(c) $\text{Br}_{2} \left(l\right) + \text{SO}_{2} \left(g\right) \rightarrow \text{Br}^{−} \left(a q\right) + \text{SO}_{4} ^{2−} \left(a q\right) (\text{in acid})$