Chapter 22

Use information from this chapter and previous chapters to write plausible chemical equations to represent the following: (a) the reaction of silver metal with \(\mathrm{HNO}_{3}(\mathrm{aq})\) (b) the complete combustion of the rocket fuel, unsymmetrical dimethylhydrazine, \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NNH}_{2}\) (c) the preparation of sodium triphosphate by heating a mixture of sodium dihydrogen phosphate and sodium hydrogen phosphate.

Draw plausible Lewis structures for (a) dimethylhydrazine, \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NNH}_{2}\) (b) nitryl chloride, \(\mathrm{ClNO}_{2}\) (Central atom is \(\mathrm{N}\) ) (c) phosphorous acid, a diprotic acid with the empirical formula \(\mathrm{H}_{3} \mathrm{PO}_{3}\).

Both nitramide and hyponitrous acid have the formula \(\mathrm{H}_{2} \mathrm{N}_{2} \mathrm{O}_{2} .\) Hyponitrous acid is a weak diprotic acid; nitramide contains the amide group \(\left(-\mathrm{NH}_{2}\right) .\) Draw plausible Lewis structures for these two substances.

Supply an appropriate name for each of the following: (a) \(\mathrm{HPO}_{4}^{2-} ;\) (b) \(\mathrm{Ca}_{2} \mathrm{P}_{2} \mathrm{O}_{7} ;\) (c) \(\mathrm{H}_{6} \mathrm{P}_{4} \mathrm{O}_{13}\).

Write an appropriate formula for each of the following: (a) hydroxylamine; (b) calcium hydrogen phosphate; (c) lithium nitride.

All the group 15 elements form trifluorides, but nitrogen is the only group 15 element that does not form a pentafluoride. (a) Suggest a reason why nitrogen does not form a pentafluoride. (b) The observed bond angle in \(\mathrm{NF}_{3}\) is approximately \(102.5^{\circ} \mathrm{C} .\) Use VSEPR theory to rationalize the structure of the \(\mathrm{NF}_{3}\) molecule.

The structures of the \(\mathrm{NH}_{3}\) and \(\mathrm{NF}_{3}\) molecules are similar, yet the dipole moment for the \(\mathrm{NH}_{3}\) molecule is rather large (1.47 debye) and that of the NF \(_{3}\) molecule is rather small (0.24 debye). Provide an explanation for this difference in the dipole moments.

Write chemical equations for the following reactions: (a) the displacement of \(\mathrm{H}_{2}(\mathrm{g})\) from \(\mathrm{HCl}(\mathrm{aq})\) by \(\mathrm{Al}(\mathrm{s})\) (b) the re-forming of propane gas \(\left(\mathrm{C}_{3} \mathrm{H}_{8}\right)\) with steam (c) the reduction of \(\mathrm{MnO}_{2}(\mathrm{s})\) to \(\mathrm{Mn}(\mathrm{s})\) with \(\mathrm{H}_{2}(\mathrm{g})\)

Write equations to show how to prepare \(\mathrm{H}_{2}(\mathrm{g})\) from each of the following substances: \((a) \mathrm{H}_{2} \mathrm{O} ;\) (b) \(\mathrm{HI}(\mathrm{aq})\) (c) \(\mathrm{Mg}(\mathrm{s}) ;\) (d) \(\mathrm{CO}(\mathrm{g})\). Use other common laboratory reactants as necessary, that is, water, acids or bases, metals, and so on.

What volume of \(\mathrm{H}_{2}(\mathrm{g})\) at \(25^{\circ} \mathrm{C}\) and \(752 \mathrm{mmHg}\) is required to hydrogenate oleic acid, \(\mathrm{C}_{17} \mathrm{H}_{33} \mathrm{COOH}(1)\) to produce one mole of stearic acid, \(\mathrm{C}_{17} \mathrm{H}_{35} \mathrm{COOH}(\mathrm{s}) ?\) Assume reaction (22.52) proceeds with a 95\% yield.

Without doing detailed calculations, explain in which of the following materials you would expect to find the greatest mass percent of hydrogen: seawater, the atmosphere, natural gas \(\left(\mathrm{CH}_{4}\right),\) ammonia.

How many grams of \(\mathrm{CaH}_{2}(\mathrm{s})\) are required to generate sufficient \(\mathrm{H}_{2}(\mathrm{g})\) to fill a \(235 \mathrm{L}\) weather observation balloon at \(722 \mathrm{mmHg}\) and \(19.7^{\circ} \mathrm{C} ?\) \(\mathrm{CaH}_{2}(\mathrm{s})+2 \mathrm{H}_{2} \mathrm{O}(1) \longrightarrow \mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{aq})+2 \mathrm{H}_{2}(\mathrm{g})\).

The amide anion \(\mathrm{NH}_{2}^{-}\) is a very strong base. On the basis of molecular orbital theory, would you expect \(\mathrm{NH}_{2}^{-}\) to be linear or bent?

On the basis of molecular orbital theory, would you expect \(\mathrm{NH}_{2}^{+}\) to be linear or bent?

The boiling points of oxygen and argon are \(-183^{\circ} \mathrm{C}\) and \(-189^{\circ} \mathrm{C},\) respectively. Because the boiling points are so similar, argon obtained from the fractional distillation of liquid air is contaminated with oxygen. The following three-step procedure can be used to obtain pure argon from the oxygen-contaminated sample: (1) Excess hydrogen is added to the mixture and then the mixture is ignited. (2) The mixture from step (1) is then passed over hot copper(II) oxide. (3) The mixture from step (2) is passed over a dehydrated zeolite material (see Chapter 21 ). Explain the purpose of each step, writing chemical equations for any reactions that occur.

In \(1988,\) G. J. Schrobilgen, professor of chemistry at McMaster University in Canada, reported the synthesis of an ionic compound, \([\mathrm{HCNKrF}]\left[\mathrm{AsF}_{6}\right],\) which consists of \(\mathrm{HCNKr} \mathrm{F}^{+}\) and \(\mathrm{AsF}_{6}^{-}\) ions. In the \(\mathrm{HCNKr} \mathrm{F}^{+}\) ion, the krypton is covalently bonded to both fluorine and nitrogen. Draw Lewis structures for these ions, and estimate the bond angles.

Zn can reduce \(\mathrm{NO}_{3}^{-}\) to \(\mathrm{NH}_{3}(\mathrm{g})\) in basic solution. (The following equation is not balanced.) $$\begin{aligned}\mathrm{NO}_{3}^{-}(\mathrm{aq})+\mathrm{Zn}(\mathrm{s})+& \mathrm{OH}^{-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \longrightarrow \\\&\left[\mathrm{Zn}(\mathrm{OH})_{4}\right]^{2-}(\mathrm{aq})+\mathrm{NH}_{3}(\mathrm{g})\end{aligned}$$ The \(\mathrm{NH}_{3}\) can be neutralized with an excess of \(\mathrm{HCl}(\mathrm{aq})\) Then, the unreacted HCl can be titrated with NaOH. In this way a quantitative determination of \(\mathrm{NO}_{3}^{-}\) can be achieved. A 25.00 mL sample of nitrate solution was treated with zinc in basic solution. The \(\mathrm{NH}_{3}(\mathrm{g})\) was passed into \(50.00 \mathrm{mL}\) of \(0.1500 \mathrm{M} \mathrm{HCl} .\) The excess \(\mathrm{HCl}\) required \(32.10 \mathrm{mL}\) of \(0.1000 \mathrm{M} \mathrm{NaOH}\) for its titration. What was the \(\left[\mathrm{NO}_{3}\right]\) in the original sample?

One reaction for the production of adipic acid, \(\mathrm{HOOC}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{COOH},\) used in the manufacture of nylon, involves the oxidation of cyclohexanone, \(\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{O},\) in a nitric acid solution. Assume that dinitrogen monoxide is also formed, and write a balanced equation for this reaction.

Despite the fact that it has the higher molecular mass, XeO \(_{4}\) exists as a gas at \(298 \mathrm{K},\) whereas \(\mathrm{XeO}_{3}\) is a solid. Give a plausible explanation for this observation.

The text mentions that ammonium perchlorate is an explosion hazard. Assuming that \(\mathrm{NH}_{4} \mathrm{ClO}_{4}\) is the sole reactant in the explosion, write a plausible equation(s) to represent the reaction that occurs.

The following bond energies are given for \(298 \mathrm{K}: \mathrm{O}_{2}\) \(498 ; \mathrm{N}_{2}, 946 ; \mathrm{F}_{2}, 159 ; \mathrm{Cl}_{2}, 243 ;\) ClF, \(251 ; \mathrm{OF}\left(\text { in } \mathrm{OF}_{2}\right)\) \(213 ; \mathrm{ClO}\left(\operatorname{in} \mathrm{Cl}_{2} \mathrm{O}\right), 205 ;\) and \(\mathrm{NF}\left(\mathrm{in} \mathrm{NF}_{3}\right), 280 \mathrm{kJmol}^{-14}\) Calculate \(\Delta H_{f}\) at \(298 \mathrm{K}\) for \(1 \mathrm{mol}\) of \((\mathrm{a}) \mathrm{ClF}(\mathrm{g})\) (b) \(\mathrm{OF}_{2}(\mathrm{g}) ;(\mathrm{c}) \mathrm{Cl}_{2} \mathrm{O}(\mathrm{g}) ;(\mathrm{d}) \mathrm{NF}_{3}(\mathrm{g})\).

Polonium is the only element known to crystallize in the simple cubic form. In this structure, the interatomic distance between a Po atom and each of its six nearest neighbors is \(335 \mathrm{pm}\). Use this description of the crystal structure to estimate the density of polonium.

One reaction of a chlorofluorocarbon implicated in the destruction of stratospheric ozone is \(\mathrm{CFCl}_{3}+h v \longrightarrow \mathrm{CFCl}_{2}+\mathrm{Cl}\) (a) What is the energy of the photons ( \(h v\) ) required to bring about this reaction, expressed in kilojoules per mole? (b) What is the frequency and wavelength of the light necessary to produce the reaction? In what portion of the electromagnetic spectrum is this light found?

Peroxonitrous acid is an unstable intermediate formed in the oxidation of \(\mathrm{HNO}_{2}\) by \(\mathrm{H}_{2} \mathrm{O}_{2}\). It has the same formula as nitric acid, HNO \(_{3}\). Show how you would expect peroxonitrous and nitric acids to differ in structure.

The structure of \(\mathrm{N}\left(\mathrm{SiH}_{3}\right)_{3}\) involves a planar arrangement of \(\mathrm{N}\) and \(\mathrm{Si}\) atoms, whereas that of the related compound \(\mathrm{N}\left(\mathrm{CH}_{3}\right)_{3}\) has a pyramidal arrangement of N and \(\mathrm{C}\) atoms. Propose bonding schemes for these molecules that are consistent with this observation.

In the extraction of bromine from seawater (reaction 22.3), seawater is first brought to a pH of 3.5 and then treated with \(\mathrm{Cl}_{2}(\mathrm{g}) .\) In practice, the \(\mathrm{pH}\) of the seawater is adjusted with \(\mathrm{H}_{2} \mathrm{SO}_{4},\) and the mass of chlorine used is \(15 \%\) in excess of the theoretical. Assuming a seawater sample with an initial pH of 7.0 a density of \(1.03 \mathrm{g} \mathrm{cm}^{-3}\), and a bromine content of 70 ppm by mass, what masses of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) and \(\mathrm{Cl}_{2}\) would be used in the extraction of bromine from \(1.00 \times 10^{3} \mathrm{L}\) of seawater?

The bond energies of \(\mathrm{Cl}_{2}\) and \(\mathrm{F}_{2}\) are 243 and \(159 \mathrm{kJ} \mathrm{mol}^{-1},\) respectively. Use these data to explain why \(\mathrm{XeF}_{2}\) is a much more stable compound than \(\mathrm{XeCl}_{2} .[\text { Hint: Recall that Xe exists as a monatomic gas. }]\).

Write plausible half-equations and a balanced oxidation-reduction equation for the disproportionation of \(\mathrm{XeF}_{4}\) to \(\mathrm{Xe}\) and \(\mathrm{XeO}_{3}\) in aqueous acidic solution. Xe and \(\mathrm{XeO}_{3}\) are produced in a 2: 1 mol ratio, and \(\mathrm{O}_{2}(\mathrm{g})\) is also produced.

The solubility of \(\mathrm{Cl}_{2}(\mathrm{g})\) in water is \(6.4 \mathrm{g} \mathrm{L}^{-1}\) at \(25^{\circ} \mathrm{C}\) Some of this chlorine is present as \(\mathrm{Cl}_{2},\) and some is found as HOCl or Cl^- For the hydrolysis reaction $$\begin{array}{c}\mathrm{Cl}_{2}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(1) \longrightarrow \\ \mathrm{HOCl}(\mathrm{aq})+\mathrm{H}_{3} \mathrm{O}^{+}(\mathrm{aq})+\mathrm{Cl}^{-}(\mathrm{aq}) \\\K_{c}=4.4 \times 10^{-4}\end{array}$$ For a saturated solution of \(\mathrm{Cl}_{2}\) in water, calculate \(\left[\mathrm{Cl}_{2}\right],[\mathrm{HOCl}],\left[\mathrm{H}_{3} \mathrm{O}^{+}\right],\) and \(\left[\mathrm{Cl}^{-}\right]\).

The heavier halogens (Cl, Br, and I) form compounds in which the central halogen atom, \(X\), is bonded directly to oxygen and to fluorine. Several examples are known, including those with formulas of the type \(\mathrm{FXO}_{2}, \mathrm{FXO}_{3, \text { and } \mathrm{F}_{3} \mathrm{XO} . \text { The structures of these }}\) molecules are all consistent with the VSEPR model. Draw Lewis structures and predict the geometries of (a) chloryl fluoride, \(\mathrm{FClO}_{2}\); (b) perchloryl fluoride, \(\mathrm{FClO}_{3} ;(\mathrm{c}) \mathrm{F}_{3} \mathrm{ClO}\).

Draw Lewis structures for \(\mathrm{O}_{3}\) and \(\mathrm{SO}_{2}\). In what ways are the structures similar? In what ways do they differ?

Chemists have successfully synthesized the ionic compound \(\left[\mathrm{N}_{5}\right]\left[\mathrm{SbF}_{6}\right],\) which consists of \(\mathrm{N}_{5}^{+}\) and \(\mathrm{SbF}_{6}^{-}\) ions. Draw Lewis structures for these ions and assign formal charges to the atoms in your structures. Describe the structures of these ions. [Hint: The skeleton structure for \(\mathrm{N}_{5}^{+}\) is \(\mathrm{N}-\mathrm{N}-\mathrm{N}-\mathrm{N}-\mathrm{N}\) and several resonance structures can be drawn.].

Various thermochemical cycles are being explored as possible sources of \(\mathrm{H}_{2}(\mathrm{g}) .\) The object is to find a series of reactions that can be conducted at moderate temperatures (about \(500^{\circ} \mathrm{C}\) ) and that results in the decomposition of water into \(\mathrm{H}_{2}\) and \(\mathrm{O}_{2} .\) Show that the following series of reactions meets these requirements. $$\begin{aligned}\mathrm{FeCl}_{2}+\mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{Fe}_{3} \mathrm{O}_{4}+\mathrm{HCl}+\mathrm{H}_{2} \\\\\mathrm{Fe}_{3} \mathrm{O}_{4}+\mathrm{HCl}+\mathrm{Cl}_{2} & \longrightarrow \mathrm{FeCl}_{3}+\mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2} \\\\\mathrm{FeCl}_{3} \longrightarrow & \mathrm{FeCl}_{2}+\mathrm{Cl}_{2}\end{aligned}$$

Figure \(15-1\) (page 656 ) shows that \(I_{2}\) is considerably more soluble in \(\mathrm{CCl}_{4}(1)\) than it is in \(\mathrm{H}_{2} \mathrm{O}(1) .\) The concentration of \(I_{2}\) in its saturated aqueous solution is \(1.33 \times 10^{-3} \mathrm{M},\) and the equilibrium achieved when \(\bar{I}_{2}\) distributes itself between \(\mathrm{H}_{2} \mathrm{O}\) and \(\mathrm{CCl}_{4}\) is $$\mathrm{I}_{2}(\mathrm{aq}) \rightleftharpoons \mathrm{I}_{2}\left(\mathrm{CCl}_{4}\right) \quad K_{\mathrm{c}}=85.5$$ (a) \(\mathrm{A} 10.0 \mathrm{mL}\) sample of saturated \(\mathrm{I}_{2}(\mathrm{aq})\) is shaken with \(10.0 \mathrm{mL} \mathrm{CCl}_{4} .\) After equilibrium is established, the two liquid layers are separated. How many milligrams of \(I_{2}\) will be in the aqueous layer? (b) If the \(10.0 \mathrm{mL}\) of aqueous layer from part (a) is extracted with a second \(10.0 \mathrm{mL}\) portion of \(\mathrm{CCl}_{4}\) how many milligrams of \(\mathrm{I}_{2}\) will remain in the aqueous layer when equilibrium is reestablished? (c) If the 10.0 mL sample of saturated \(I_{2}(\) aq) in part (a) had originally been extracted with \(20.0 \mathrm{mL} \mathrm{CCl}_{4}\) would the mass of \(I_{2}\) remaining in the aqueous layer have been less than, equal to, or greater than that in part (b)? Explain.

The so-called pyroanions, \(\mathrm{X}_{2} \mathrm{O}_{7}^{n-},\) form a series of structurally similar polyatomic anions for the elements Si, P, and S. (a) Draw the Lewis structures of these anions, and predict the geometry of the anions. What is the maximum number of atoms that can lie in a plane? (b) Each pyroanion in part (a) corresponds to a pyroacid, \(\mathrm{X}_{2} \mathrm{O}_{7} \mathrm{H}_{n} .\) Compare each pyroacid to the acid containing only one atom of the element in its maximum oxidation state. From this comparison, suggest a strategy for the preparation of these pyroacids. (c) What is the chlorine analogue of the pyroanions? For which acid is this species the anhydride?

The sketch is a portion of the phase diagram for the element sulfur. The transition between solid orthorhombic \(\left(S_{\alpha}\right)\) and solid monoclinic \(\left(S_{\beta}\right)\) sulfur, in the presence of sulfur vapor, is at \(95.3^{\circ} \mathrm{C} .\) The triple point involving monoclinic sulfur, liquid sulfur, and sulfur vapor is at \(119^{\circ} \mathrm{C}\) (a) How would you modify the phase diagram to represent the melting of orthorhombic sulfur that is sometimes observed at \(113^{\circ} \mathrm{C} ?[\) Hint: What would the phase diagram look like if the monoclinic sulfur did not form? (b) Account for the observation that if a sample of rhombic sulfur is melted at \(113^{\circ} \mathrm{C}\) and then heated, the liquid sulfur freezes at \(119^{\circ} \mathrm{C}\) upon cooling.

In your own words, define the following terms: (a) polyhalide ion; (b) polyphosphate; (c) interhalogen; (d) disproportionation.

Briefly describe each of the following terms: (a) Frasch process; (b) water gas reactions; (c) eutrophication; (d) electrode potential diagram.

Explain the important distinctions between each pair of terms: (a) acid salt and acid anhydride; (b) azide and nitride; (c) white phosphorus and red phosphorus; (d) ionic hydride and metallic hydride.

To displace \(\mathrm{Br}_{2}\) from an aqueous solution of \(\mathrm{Br}^{-}\) add \((\mathrm{a}) \mathrm{I}_{2}(\mathrm{aq}) ;\) (b) \(\mathrm{Cl}_{2}(\mathrm{aq}) ;\) (c) \(\mathrm{H}_{2}(\mathrm{g}) ;\) (d) \(\mathrm{Cl}^{-}(\mathrm{aq})\) (e) \(\mathrm{I}_{3}^{-}(\mathrm{aq})\).

All of the following compounds yield \(\mathrm{O}_{2}(\mathrm{g})\) when heated to about \(1000 \mathrm{K}\) except (a) \(\mathrm{KClO}_{3} ;\) (b) \(\mathrm{KClO}_{4}\) (c) \(\mathrm{N}_{2} \mathrm{O} ;\) (d) \(\mathrm{CaCO}_{3} ;\) (e) \(\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}\).

All of the following substances are bases except for (a) \(\mathrm{H}_{2} \mathrm{NNH}_{2} ;\) (b) \(\mathrm{NH}_{3} ;\) (c) \(\mathrm{HN}_{3} ;\) (d) \(\mathrm{NH}_{2} \mathrm{OH}\); (e) \(\mathrm{CH}_{3} \mathrm{NH}_{2}\).

The best reducing agent of the following substances is (a) \(\mathrm{H}_{2} \mathrm{S} ;\) (b) \(\mathrm{O}_{3} ;\) (c) \(\mathrm{H}_{2} \mathrm{SO}_{4} ;\) (d) \(\mathrm{NaF}\); (e) \(\mathrm{H}_{2} \mathrm{O}\).

All of the following have a tetrahedral shape except (a) \(\mathrm{SO}_{4}^{2-} ;\) (b) \(\mathrm{XeF}_{4} ;\) (c) \(\mathrm{CCl}_{4} ;\) (d) \(\mathrm{XeO}_{4} ;\) (e) \(\mathrm{NH}_{4}^{+}\)..

Two of the following, through a reaction occurring in a weakly acidic solution, produce the same gaseous product. They are (a) \(\mathrm{CaH}_{2}(\mathrm{s}) ;\) (b) \(\mathrm{Na}_{2} \mathrm{O}_{2}(\mathrm{s})\) (c) \(\mathrm{NaOH}(\mathrm{s}) ;(\mathrm{d}) \mathrm{Al}(\mathrm{s}) ;(\mathrm{e}) \mathrm{NaHCO}_{3}(\mathrm{s}) ;(\mathrm{f}) \mathrm{N}_{2} \mathrm{H}_{4}(1)\).

Write a plausible chemical equation to represent the reaction of \((\mathrm{a}) \mathrm{Cl}_{2}(\mathrm{g}) \quad\) with cold \(\quad \mathrm{NaOH}(\mathrm{aq})\) (b) \(\mathrm{NaI}(\mathrm{s})\) with hot \(\mathrm{H}_{2} \mathrm{SO}_{4}(\text { concd aq }) ;\) (c) \(\mathrm{Cl}_{2}(\mathrm{g})\) with \(\mathrm{KI}_{3}(\mathrm{aq}) ; \quad\) (d) \(\quad \mathrm{NaBr}(\mathrm{s}) \quad\) with hot \(\mathrm{H}_{3} \mathrm{PO}_{4}\) \((\text { concd aq })\) (e) \(\mathrm{NaHSO}_{3}(\mathrm{aq})\) with \(\mathrm{MnO}_{4}^{-1}(\mathrm{aq})\) in dilute \(\mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{aq})\).

Give a practical laboratory method that you might use to produce small quantities of the following gases and comment on any difficulties that might arise: (a) \(\mathrm{O}_{2} ;\) (b) \(\mathrm{NO} ;\) (c) \(\mathrm{H}_{2} ;\) (d) \(\mathrm{NH}_{3} ;\) (e) \(\mathrm{CO}_{2}\).

Complete and balance equations for these reactions. (a) \(\operatorname{LiH}(s)+H_{2} O(1) \longrightarrow\) (b) \(\mathrm{C}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \stackrel{\Delta}{\longrightarrow}\) (c) \(\mathrm{NO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(1) \longrightarrow\)

If \(\mathrm{Br}^{-}\) and \(\mathrm{I}^{-}\) occur together in an aqueous solution, I can be oxidized to \(\mathrm{IO}_{3}^{-}\) with an excess of \(\mathrm{Cl}_{2}(\mathrm{aq})\) Simultaneously, \(\mathrm{Br}^{-}\) is oxidized to \(\mathrm{Br}_{2},\) which is extracted with \(\mathrm{CS}_{2}(1) .\) Write chemical equations for the reactions that occur.

Suppose that the sulfur present in seawater as \(\mathrm{SO}_{4}^{2-}\) \(\left(2650 \mathrm{mg} \mathrm{L}^{-1}\right)\) could be recovered as elemental sulfur. If this sulfur were then converted to \(\mathrm{H}_{2} \mathrm{SO}_{4},\) how many cubic kilometers of seawater would have to be processed to yield the average U.S. annual consumption of about 45 million tons of \(\mathrm{H}_{2} \mathrm{SO}_{4} ?\)