Chapter 19

What is meant by hydrogen burning and helium burning in relation to the formation of elements?

Identify the most abundant nonmetallic element in Earth's crust. Identify the most abundant metallic element in Earth's crust.

Describe the difference between an ore and a mineral.

Explain how the silicate unit in mica and other sheet silicates has the general formula \(\mathrm{Si}_{2} \mathrm{O}_{5}^{2-}\).

Identify two major differences between white phosphorus and red phosphorus.

Identify (a) two elements obtained from the atmosphere. (b) two elements obtained from the sea. (c) two elements obtained from Earth's crust.

Why are nitrogen and oxygen important industrial chemicals?

Describe how nature fixes nitrogen. Why is nitrogen fixation necessary?

Identify two uses of phosphate rock.

Why is phosphate rock not applied directly as a phosphorus fertilizer?

Write balanced equations to represent nuclear fusion reactions for (a) the conversion of oxygen-16 into neon-20. (b) carbon "burning" to form neon-20.

Describe how heavier elements are formed from lighter elements.

Explain the differences between the s process and the \(r\) process of element formation.

Identify six elements that are found in nature in uncombined form.

Identify the most abundant metalloid element in Earth's crust.

Describe the difference between amphibole and serpentine forms of asbestos in terms of their potential as health hazards.

Identify four different anions that are common in minerals in Earth's crust. Give an example of each type of mineral.

Give a simple explanation for the abundance of clay minerals in Earth's crust.

Explain how the silicate unit in amphiboles has the general formula \(\mathrm{Si}_{4} \mathrm{O}_{11}^{6-}\).

What physical property allows the separation of nitrogen, oxygen, and argon from each other in fractional distillation of air?

Describe two different methods for obtaining pure sulfur.

Identify the elements obtained by (a) the Linde process. (b) the Frasch process.

A \(500-\mathrm{g}\) sample of gaseous argon is collected at \(-185^{\circ} \mathrm{C}\) and 5.0 atm. Calculate its volume at this temperature and pressure.

Identify the substance or substances produced by each of these commercial processes and write a balanced chemical equation for the main reaction of the process. (a) Downs (b) Chlor-alkali (c) Dow (d) Hall-Héroult

Write balanced equations for the recovery of magnesium from seawater. Begin with the precipitation of magnesium hydroxide by addition of calcium hydroxide to seawater.

(a) Write the balanced chemical equation for the electrolysis of aqueous \(\mathrm{NaCl}\). (b) In \(2002,8.98 \times 10^{9} \mathrm{~kg} \mathrm{NaOH}\) and \(1.14 \times 10^{10} \mathrm{~kg}\) chlorine were produced in the United States. Does the ratio of these masses agree with the ratio of masses from the balanced chemical equation? If not, what does that suggest about the ways that \(\mathrm{NaOH}\) and \(\mathrm{Cl}_{2}\) are produced?

Briefly explain why different products are obtained from the electrolysis of molten \(\mathrm{NaCl}\) and the electrolysis of aqueous \(\mathrm{NaCl}\).

To produce magnesium metal, \(1000 . \mathrm{kg}\) molten \(\mathrm{MgCl}_{2}\) are electrolyzed. (a) At which electrode is magnesium produced? (b) What is produced at the other electrode? (c) Calculate the amount (mol) of electrons used in the process. (d) An industrial process uses \(8.4 \mathrm{kWh}\) per pound of \(\mathrm{Mg}\). Calculate the energy (J) required per mole of magnesium.

A Downs cell operates at \(7.0 \mathrm{~V}\) and \(4.0 \times 10^{4} \mathrm{~A}\). (a) Calculate how much \(\mathrm{Na}(\mathrm{s})\) and \(\mathrm{Cl}_{2}(\mathrm{~g})\) can be produced in 24 hours by such a cell. (b) Assuming \(100 \%\) efficiency, calculate the energy consumption (kWh) of this cell.

Calculate how much energy \((\mathrm{kWh})\) is required to prepare a ton of sodium in a typical Downs cell operating at \(25,000 \mathrm{~A}\) and \(7.0 \mathrm{~V}\).

Calculate the mass in grams of aluminum that can be produced when \(6.0 \times 10^{4} \mathrm{~A}\) is passed through a series of 100 Hall-Héroult electrolytic cells operating at \(85 \%\) efficiency for 24 hours.

Calculate what mass in grams of aluminum can be produced from the electrolysis of molten \(\mathrm{AlCl}_{3}\) in an electrolytic cell operating at 100 . A for \(2.00 \mathrm{hr}\).

Phosphine, \(\mathrm{PH}_{3}\), is a hydride of phosphorus as ammonia, \(\mathrm{NH}_{3}\), is of nitrogen. Explain why phosphine boils at a much lower temperature than \(\mathrm{NH}_{3}\) in spite of having a molar mass twice that of ammonia.

Given: $$\begin{array}{ll} \mathrm{F}_{2}(\mathrm{~g})+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{~F}^{-}(\mathrm{aq}) & E^{\circ}=+2.87\mathrm{~V} \\ \mathrm{Cl}_{2}(\mathrm{~g})+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{Cl}^{-}(\mathrm{aq}) & E^{\circ}=+1.36\mathrm{~V} \end{array}$$ determine whether this reaction is product-favored: $$\mathrm{Cl}_{2}(\mathrm{~g})+2 \mathrm{~F}^{-}(\mathrm{aq}) \longrightarrow 2 \mathrm{Cl}^{-}(\mathrm{aq})+\mathrm{F}_{2}(\mathrm{~g})$$

Given: $$\begin{array}{ll} \mathrm{Br}_{2}(\ell)+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{Br}^{-}(\mathrm{aq}) & E^{\circ}=+1.07\mathrm{~V} \\ \mathrm{I}_{2}(\mathrm{~s})+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{I}^{-}(\mathrm{aq}) & E^{\circ}=+0.54 \mathrm{~V}\end{array}$$ determine whether this reaction is product-favored: $$\mathrm{Br}_{2}(\mathrm{~g})+2 \mathrm{I}^{-}(\mathrm{aq}) \longrightarrow 2 \mathrm{Br}^{-}(\mathrm{aq})+\mathrm{I}_{2}(\mathrm{~s})$$

Given: $$\begin{array}{ll} \mathrm{F}_{2}(\mathrm{~g})+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{~F}^{-}(\mathrm{aq}) & E^{\circ}=+2.87 \mathrm{~V} \\ \mathrm{Br}_{2}(\ell)+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{Br}^{-}(\mathrm{aq}) & E^{\circ}=+1.07 \mathrm{~V} \end{array}$$ determine whether this reaction is product-favored: $$\mathrm{F}_{2}(\mathrm{~g})+2 \mathrm{Br}^{-}(\mathrm{aq}) \longrightarrow 2 \mathrm{~F}^{-}(\mathrm{aq})+\mathrm{Br}_{2}(\ell)$$

Identify the substance or substances produced by each of these commercial processes and write balanced chemical equations for all reactions in each process. (a) Ostwald (b) Contact (c) Haber-Bosch

Phosphorus forms two oxides, \(\mathrm{P}_{4} \mathrm{O}_{6}\) and \(\mathrm{P}_{4} \mathrm{O}_{10}\) (a) Determine the oxidation number of phosphorus in each of these compounds. (b) Write Lewis structures for each compound.

A human body contains approximately \(5 \mathrm{~L}\) of blood. A bipolar disorder patient receives \(2.0 \mathrm{~g}\) lithium carbonate as a daily dose. Calculate the concentration of \(\mathrm{Li}^{+}(\mathrm{mmol} / \mathrm{L})\) that this dosage provides.

Metallic tin was obtained in ancient times by the reaction of the principal tin ore, cassiterite, \(\mathrm{SnO}_{2},\) with carbon from a charcoal fire: $$\mathrm{SnO}_{2}(\mathrm{~s})+2 \mathrm{C}(\mathrm{s}) \longrightarrow 2 \mathrm{CO(\mathrm{g})+\mathrm{Sn}(\mathrm{s})$$ Identify the oxidizing and reducing agents in this reaction.

Galena, \(\mathrm{PbS},\) is the principal lead ore. To produce lead metal, galena is first reacted with oxygen; the oxide is then reacted with carbon. (a) Write balanced chemical equations for these two reactions. (b) Is either of these reactions a redox reaction? If so, explain your answer by identifying the oxidizing and reducing agent in each case.

Which of these is soluble in carbon disulfide, \(\mathrm{CS}_{2}\) ? (a) water (b) benzene, \(\mathrm{C}_{6} \mathrm{H}_{6}\) (c) white phosphorus (d) iodine (e) ethanol, \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\) Explain your answers.

Molten \(\mathrm{NaCl}\) is electrolyzed in a Downs cell operating at \(1.00 \times 10^{4} \mathrm{~A}\) for \(24 \mathrm{hr}\) (a) Calculate the mass in grams of sodium produced. (b) Calculate the volume of \(\mathrm{Cl}_{2}\) in liters that is collected from the outlet tube at \(20 .{ }^{\circ} \mathrm{C}\) and \(15 \mathrm{~atm} .\)

Bauxite, the principal source of aluminum oxide, contains \(55 \% \mathrm{Al}_{2} \mathrm{O}_{3} .\) Calculate how much bauxite is required to produce the \(5.0 \times 10^{6}\) tons of \(\mathrm{Al}\) produced annually by electrolysis.

Write a plausible Lewis structure for azide ion, \(\mathrm{N}_{3}^{-}\).

Write a plausible Lewis structure for \(\mathrm{P}_{4} \mathrm{O}_{10}\).

Write the chemical equation for the (a) combustion of white phosphorus. (b) reaction of the combustion product with water.

Estimate the temperature at which the conversion of white phosphorus to red phosphorus occurs. \(\Delta_{\mathrm{r}} H^{\circ}=-70.4 \mathrm{~kJ} / \mathrm{mol} ; \Delta_{\mathrm{r}} S^{\circ}=-73.16 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}\) at \(25^{\circ} \mathrm{C}\).

There are two common oxides of sulfur. Name these oxides, and write chemical equations for the reaction of each with water. Identify the products.

What raw materials are used to produce sulfuric acid? Write chemical equations to represent the steps in the contact process to produce sulfuric acid.