Chapter 7: Stoichiometry of Chemical ReactionsContent check — Chemistry: Atoms First, Chapter 7: Stoichiometry of Chemical Reactions

Write balanced molecular, complete ionic, and net ionic equations for this process.

(a) KNO₃

(b) AlH₃

(c) $\underset{\_}{\text{N}}{\text{H}}_4{}^{+}$

(d) ${\text{H}}_2\underset{\_}{\text{P}}{\text{O}}_4{}^{-}$

Is this a redox reaction? If so, provide a more specific name for the reaction if appropriate, and identify the oxidant and reductant.

A volume of 23.24 mL was required to reach the end point. What is the oxalic acid molarity?

Balance the following equations:

(a) ${\text{PCl}}_5(s)+$ ${\text{H}}_2\text{O}(l)⟶$ ${\text{POCl}}_3(l)+$ $\text{HCl}(aq)$

(b) $\text{Cu}(s)+$ ${\text{HNO}}_3(aq)⟶$ $\text{Cu}{({\text{NO}}_3)}_2(aq)+$ ${\text{H}}_2\text{O}(l)+$ $\text{NO}(g)$

(c) ${\text{H}}_2(g)+$ ${\text{I}}_2(s)⟶$ $\text{HI}(s)$

(d) $\text{Fe}(s)+$ ${\text{O}}_2(g)⟶$ ${\text{Fe}}_2{\text{O}}_3(s)$

(e) $\text{Na}(s)+$ ${\text{H}}_2\text{O}(l)⟶$ $\text{NaOH}(aq)+$ ${\text{H}}_2(g)$

(f) $({\text{NH}}_4{)}_2{\text{Cr}}_2{\text{O}}_7(s)⟶$ ${\text{Cr}}_2{\text{O}}_3(s)+$ ${\text{N}}_2(g)+$ ${\text{H}}_2\text{O}(g)$

(g) ${\text{P}}_4(s)+$ ${\text{Cl}}_2(g)⟶$ ${\text{PCl}}_3(l)$

(h) ${\text{PtCl}}_4(s)⟶$ $\text{Pt}(s)+$ ${\text{Cl}}_2(g)$

Write a balanced molecular equation describing each of the following chemical reactions.

(a) Solid calcium carbonate is heated and decomposes to solid calcium oxide and carbon dioxide gas.

(b) Gaseous butane, C₄H₁₀, reacts with diatomic oxygen gas to yield gaseous carbon dioxide and water vapor.

(c) Aqueous solutions of magnesium chloride and sodium hydroxide react to produce solid magnesium hydroxide and aqueous sodium chloride.

(d) Water vapor reacts with sodium metal to produce solid sodium hydroxide and hydrogen gas.

Colorful fireworks often involve the decomposition of barium nitrate and potassium chlorate and the reaction of the metals magnesium, aluminum, and iron with oxygen.

(a) Write the formulas of barium nitrate and potassium chlorate.

(b) The decomposition of solid potassium chlorate leads to the formation of solid potassium chloride and diatomic oxygen gas. Write an equation for the reaction.

(c) The decomposition of solid barium nitrate leads to the formation of solid barium oxide, diatomic nitrogen gas, and diatomic oxygen gas. Write an equation for the reaction.

(d) Write separate equations for the reactions of the solid metals magnesium, aluminum, and iron with diatomic oxygen gas to yield the corresponding metal oxides. (Assume the iron oxide contains Fe³⁺ ions.)

Aqueous hydrogen fluoride (hydrofluoric acid) is used to etch glass and to analyze minerals for their silicon content. Hydrogen fluoride will also react with sand (silicon dioxide).

(a) Write an equation for the reaction of solid silicon dioxide with hydrofluoric acid to yield gaseous silicon tetrafluoride and liquid water.

(b) The mineral fluorite (calcium fluoride) occurs extensively in Illinois. Solid calcium fluoride can also be prepared by the reaction of aqueous solutions of calcium chloride and sodium fluoride, yielding aqueous sodium chloride as the other product. Write complete and net ionic equations for this reaction.

From the balanced molecular equations, write the complete ionic and net ionic equations for the following:

(a) ${\text{K}}_2{\text{C}}_2{\text{O}}_4(aq)+$ $\text{Ba}{\text{(OH)}}_2(aq)⟶$ $2\text{KOH}(aq)+$ ${\text{BaC}}_2{\text{O}}_4(s)$

(b) $\text{Pb}({\text{N}{\text{O}}_3)}_2(aq)+$ ${\text{H}}_2{\text{SO}}_4(aq)⟶$ ${\text{PbSO}}_4(s)+$ $2{\text{HNO}}_3(aq)$

(c) ${\text{CaCO}}_3(s)+$ ${\text{H}}_2{\text{SO}}_4(aq)⟶$ ${\text{CaSO}}_4(s)+$ ${\text{CO}}_2(g)+$ ${\text{H}}_2\text{O}(l)$

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

(a) $\text{Ca}(s)+$ ${\text{Br}}_2(l)⟶$ ${\text{CaBr}}_2(s)$

(b) $\text{Ca}{\text{(OH)}}_2(aq)+$ $2\text{HBr}(aq)⟶$ ${\text{CaBr}}_2(aq)+$ $2{\text{H}}_2\text{O}(l)$

(c) ${\text{C}}_6{\text{H}}_{12}(l)+$ $9{\text{O}}_2(g)⟶$ $6{\text{CO}}_2(g)+$ $6{\text{H}}_2\text{O}(g)$

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) ${\text{Na}}_2\text{S}(aq)+$ $2\text{HCl}(aq)⟶$ $2\text{NaCl}(aq)+$ ${\text{H}}_2\text{S}(g)$

(b) $2\text{Na}(s)+$ $2\text{HCl}(aq)⟶$ $2\text{NaCl}(aq)+$ ${\text{H}}_2(g)$

(c) $\text{Mg}(s)+$ ${\text{Cl}}_2(g)⟶$ ${\text{MgCl}}_2(s)$

(d) $\text{MgO}(s)+$ $2\text{HCl}(aq)⟶$ ${\text{MgCl}}_2(aq)+$ ${\text{H}}_2\text{O}(l)$

(e) ${\text{K}}_3\text{P}(s)+$ $2{\text{O}}_2(g)⟶$ ${\text{K}}_3{\text{PO}}_4(s)$

(f) $3\text{KOH}(aq)+$ ${\text{H}}_3{\text{PO}}_4(aq)⟶$ ${\text{K}}_3{\text{PO}}_4(aq)+$ $3{\text{H}}_2\text{O}(l)$

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) $\text{Al}(s)+$ ${\text{F}}_2(g)⟶$ $$

(b) $\text{Al}(s)+$ ${\text{CuBr}}_2(aq)⟶$ $$ (single displacement)

(c) ${\text{P}}_4(s)+$ ${\text{O}}_2(g)⟶$ $$

(d) $\text{Ca}(s)+$ ${\text{H}}_2\text{O}(l)⟶$ $$ (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) $\text{Mg}{\text{(OH)}}_2(s)+$ ${\text{HClO}}_4(aq)⟶$ $$

(b) ${\text{SO}}_3(g)+$ ${\text{H}}_2\text{O}(l)⟶$ $\text{(assume an excess of water and that the product dissolves)}$

(c) $\text{SrO}(s)+$ ${\text{H}}_2{\text{SO}}_4(l)⟶$ $$

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

(a) $\text{Ca}{(\text{OH})}_2(s)+$ ${\text{H}}_2\text{S}(g)⟶$ $$

(b) ${\text{Na}}_2{\text{CO}}_3(aq)+$ ${\text{H}}_2\text{S}(g)⟶$ $$

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 liquid molecular bromine via a one-step redox reaction

(c) gaseous H₂S from solid Zn and S via a two-step process (first a redox reaction between the starting materials, then reaction of the product with a strong acid)

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

(a) ${\text{Sn}}^{\mathrm{4+}}(aq)⟶$ ${\text{Sn}}^{\mathrm{2+}}(aq)$

(b) ${\left[\text{Ag}{({\text{NH}}_3)}_2\right]}^{\text{+}}(aq)⟶$ $\text{Ag}(s)+$ ${\text{NH}}_3(aq)$

(c) ${\text{Hg}}_2{\text{Cl}}_2(s)⟶$ $\text{Hg}(l)+$ ${\text{Cl}}^{\text{−}}(aq)$

(d) ${\text{H}}_2\text{O}(l)⟶$ ${\text{O}}_2(g)$ (in acidic solution)

(e) ${\text{IO}}_3{}^{\text{−}}(aq)⟶$ ${\text{I}}_2(s)$ (in basic solution)

(f) ${\text{SO}}_3{}^{\mathrm{2-}}(aq)⟶$ ${\text{SO}}_4{}^{\mathrm{2-}}(aq)$ (in acidic solution)

(g) ${\text{MnO}}_4{}^{\text{−}}(aq)⟶$ ${\text{Mn}}^{\mathrm{2+}}(aq)$ (in acidic solution)

(h) ${\text{Cl}}^{\text{−}}(aq)⟶$ ${\text{ClO}}_3{}^{\text{−}}(aq)$ (in basic solution)

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

(a) ${\text{Sn}}^{\mathrm{2+}}(aq)+$ ${\text{Cu}}^{\mathrm{2+}}(aq)⟶$ ${\text{Sn}}^{\mathrm{4+}}(aq)+$ ${\text{Cu}}^{\text{+}}(aq)$

(b) ${\text{H}}_2\text{S}(g)+$ ${\text{Hg}}_2{}^{\mathrm{2+}}(aq)⟶$ $\text{H}g(l)+$ $\text{S}(s)\text{(in acid)}$

(c) ${\text{CN}}^{\text{−}}(aq)+$ ${\text{ClO}}_2(aq)⟶$ ${\text{CNO}}^{\text{−}}(aq)+$ ${\text{Cl}}^{\text{−}}(aq)\text{(in acid)}$

(d) ${\text{Fe}}^{\mathrm{2+}}(aq)+$ ${\text{Ce}}^{\mathrm{4+}}(aq)⟶$ ${\text{Fe}}^{\mathrm{3+}}(aq)+$ ${\text{Ce}}^{\mathrm{3+}}(aq)$

(e) $\text{HBrO}(aq)⟶$ ${\text{Br}}^{\text{−}}(aq)+$ ${\text{O}}_2(g)\text{(in acid)}$

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

(a) ${\text{MnO}}_4{}^{\text{−}}(aq)+$ ${\text{NO}}_2{}^{\text{−}}(aq)⟶$ ${\text{MnO}}_2(s)+$ ${\text{NO}}_3{}^{\text{−}}(aq)\text{(in base)}$

(b) ${\text{MnO}}_4{}^{\mathrm{2-}}(aq)⟶$ ${\text{MnO}}_4{}^{\text{−}}(aq)+$ ${\text{MnO}}_2(s)\text{(in base)}$

(c) ${\text{Br}}_2(l)+$ ${\text{SO}}_2(g)⟶$ ${\text{Br}}^{\text{−}}(aq)+$ ${\text{SO}}_4{}^{\mathrm{2-}}(aq)\text{(in acid)}$

Gallium chloride is formed by the reaction of 2.6 L of a 1.44 M solution of HCl according to the following equation: $2\text{Ga}+$ $6\text{HCl}⟶$ $2{\text{GaCl}}_3+$ $3{\text{H}}_2.$

(a) Outline the steps necessary to determine the number of moles and mass of gallium chloride.

(b) Perform the calculations outlined.

Silver is often extracted from ores such as K[Ag(CN)₂] and then recovered by the reaction
$2\text{K}\left[\text{Ag}{(\text{CN})}_2\right](aq)+$ $\text{Zn}(s)⟶$ $\text{2Ag}(s)+$ $\text{Zn}{(\text{CN})}_2(aq)+$ $2\text{KCN}(aq)$

(a) How many molecules of Zn(CN)₂ are produced by the reaction of 35.27 g of K[Ag(CN)₂]?

(b) What mass of Zn(CN)₂ is produced?

Toluene, C₆H₅CH₃, is oxidized by air under carefully controlled conditions to benzoic acid, C₆H₅CO₂H, which is used to prepare the food preservative sodium benzoate, C₆H₅CO₂Na. What is the percent yield of a reaction that converts 1.000 kg of toluene to 1.21 kg of benzoic acid?

$2{\text{C}}_6{\text{H}}_5{\text{CH}}_3+$ $3{\text{O}}_2⟶$ $2{\text{C}}_6{\text{H}}_5{\text{CO}}_2\text{H}+$ $2{\text{H}}_2\text{O}$

Outline the steps needed to solve the following problem, then do the calculations. Ether, (C₂H₅)₂O, which was originally used as an anesthetic but has been replaced by safer and more effective medications, is prepared by the reaction of ethanol with sulfuric acid.

2C₂H₅OH + H₂SO₄ ⟶ (C₂H₅)₂O + H₂SO₄·H₂O

What is the percent yield of ether if 1.17 L (d = 0.7134 g/mL) is isolated from the reaction of 1.500 L of C₂H₅OH
(d = 0.7894 g/mL)?

Outline the steps needed to determine the limiting reactant when 0.50 mol of Cr and 0.75 mol of H₃PO₄ react according to the following chemical equation.
$2\text{Cr}+$ $2{\text{H}}_3{\text{PO}}_4⟶$ $2{\text{CrPO}}_4+$ $3{\text{H}}_2$

Determine the limiting reactant.

Uranium can be isolated from its ores by dissolving it as UO₂(NO₃)₂, then separating it as solid UO₂(C₂O₄)·3H₂O. Addition of 0.4031 g of sodium oxalate, Na₂C₂O₄, to a solution containing 1.481 g of uranyl nitrate, UO₂(NO₃)₂, yields 1.073 g of solid UO₂(C₂O₄)·3H₂O.

Na₂C₂O₄ + UO₂(NO₃)₂ + 3H₂O ⟶ UO₂(C₂O₄)·3H₂O + 2NaNO₃

Determine the limiting reactant and the percent yield of this reaction.

How many molecules of the sweetener saccharin can be prepared from 30 C atoms, 25 H atoms, 12 O atoms, 8 S atoms, and 14 N atoms?

In a common medical laboratory determination of the concentration of free chloride ion in blood serum, a serum sample is titrated with a Hg(NO₃)₂ solution.
$2{\text{Cl}}^{\text{−}}(aq)+$ $\text{Hg}{({\text{NO}}_3)}_2(aq)⟶$ $2{\text{NO}}_3{}^{\text{−}}(aq)+$ ${\text{HgCl}}_2(s)$

What is the Cl⁻ concentration in a 0.25-mL sample of normal serum that requires 1.46 mL of 8.25 $\times$ 10⁻⁴ M Hg(NO₃)₂(aq) to reach the end point?

A sample of solid calcium hydroxide, Ca(OH)₂, is allowed to stand in water until a saturated solution is formed. A titration of 75.00 mL of this solution with 5.00 $\times$ 10⁻² M HCl requires 36.6 mL of the acid to reach the end point.
$\text{Ca}{(\text{OH})}_2(aq)+$ $2\text{HCl}(aq)⟶$ ${\text{CaCl}}_2(aq)+$ $2{\text{H}}_2\text{O}(l)$

What is the molarity?