Chapter 22

Complete and balance the following equations: (a) \(\mathrm{CO}_{2}(g)+\mathrm{OH}^{-}(a q) \longrightarrow\) (b) \(\mathrm{NaHCO}_{3}(s)+\mathrm{H}^{+}(a q) \longrightarrow\) (c) \(\mathrm{CaO}(s)+\mathrm{C}(s) \stackrel{\Delta}{\longrightarrow}\) (d) \(\mathrm{C}(s)+\mathrm{H}_{2} \mathrm{O}(g) \stackrel{\Delta}{\longrightarrow}\) (e) \(\mathrm{CuO}(s)+\mathrm{CO}(g) \longrightarrow\)

Write a balanced equation for each of the following reactions: (a) Hydrogen cyanide is formed commercially by passing a mixture of methane, ammonia, and air over a catalyst at \(800^{\circ} \mathrm{C}\). Water is a by-product of the reaction. (b) Baking soda reacts with acids to produce carbon dioxide gas. (c) When barium carbonate reacts in air with sulfur dioxide, barium sulfate and carbon dioxide form.

Write a balanced equation for each of the following reactions: (a) Burning magnesium metal in a carbon dioxide atmosphere reduces the \(\mathrm{CO}_{2}\) to carbon. (b) In photosynthesis, solar energy is used to produce glucose \(\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)\) and \(\mathrm{O}_{2}\) from carbon dioxide and water. (c) When carbonate salts dissolve in water, they produce basic solutions.

Write the formulas for the following compounds, and indicate the oxidation state of the group 14 element or of boron in each: (a) silane, (b) germanium dichloride, (c) tin(II) sulfide, \((\mathbf{d})\) sodium borohydride, \((\mathbf{e})\) lead(IV) nitrate, \((\mathbf{f})\) tin dioxide.

Write the formulas for the following compounds, and indicate the oxidation state of the group 14 element or of boron in each: (a) stannous fluoride, (b) germane, (c) diborane, (d) tin(II) sulfate, \((\mathbf{e})\) tin selenide, \((\mathbf{f})\) zinc carbonate.

Select the member of group 14 that best fits each description: (a) has the highest electronegativity, \((\mathbf{b})\) a metalloid which is commonly used in computer chips, \((\mathbf{c})\) is used for shielding for radiation.

Select the member of group 14 that best fits each description: (a) has the greatest tendency to form multiple bonds with itself, (b) forms polymeric structures with oxygen, (c) is a metal with +2 and +4 oxidation states.

Speculate as to why carbon forms carbonate rather than silicate analogs.

\(\begin{array}{ll} & (\mathbf{a}) \text { How does the structure of diborane }\left(\mathrm{B}_{2} \mathrm{H}_{6}\right) \text { differ from }\end{array}\) that of ethane \(\left(\mathrm{C}_{2} \mathrm{H}_{6}\right) ?(\mathbf{b})\) Explain why diborane adopts the geometry that it does. (c) What is the significance of the statement that the hydrogen atoms in diborane are described as "hydridic"?

Write a balanced equation for each of the following reactions: (a) Diborane reacts with water to form boric acid and molecular hydrogen. (b) Upon heating, boric acid undergoes a condensation reaction to form tetraboric acid. (c) Boron oxide dissolves in water to give a solution of boric acid.

Although the \(\mathrm{ClO}_{4}^{-}\) and \(\mathrm{IO}_{4}^{-}\) ions have been known for a long time, \(\mathrm{BrO}_{4}^{-}\) was not synthesized until 1965 . The ion was synthesized by oxidizing the bromate ion with xenon difluoride, producing xenon, hydrofluoric acid, and the perbromate ion. (a) Write the balanced equation for this reaction. (b) What are the oxidation states of Br in the Br-containing species in this reaction?

What is the anhydride for each of the following acids: (c) \(\mathrm{HNO}_{2}\) (a) \(\mathrm{H}_{2} \mathrm{SO}_{4},\) (b) \(\mathrm{HClO}_{3}\), (d) \(\mathrm{H}_{2} \mathrm{CO}_{3}\), (e) \(\mathrm{H}_{3} \mathrm{PO}_{4} ?\)

Hydrogen peroxide is capable of oxidizing (a) hydrazine to \(\mathrm{N}_{2}\) and \(\mathrm{H}_{2} \mathrm{O},(\mathbf{b}) \mathrm{SO}_{2}\) to \(\mathrm{SO}_{4}^{2-},(\mathbf{c}) \mathrm{NO}_{2}^{-}\) to \(\mathrm{NO}_{3}^{-},(\mathbf{d}) \mathrm{H}_{2} \mathrm{~S}(g)\) to \(\mathrm{S}(s),(\mathbf{e}) \mathrm{Fe}^{2+}\) to \(\mathrm{Fe}^{3+}\). Write a balanced net ionic equation for each of these redox reactions.

(a) What is the oxidation state of \(\mathrm{P}\) in \(\mathrm{PF}_{6}^{-}\) and of \(\mathrm{N}\) in \(\mathrm{NF}_{3}\) ? (b) Why doesn't \(\mathrm{N}\) form \(\mathrm{NF}_{6}^{-}\) ion analogous to \(\mathrm{P}\) ?

Write a balanced chemical reaction for the condensation reaction between \(\mathrm{H}_{3} \mathrm{PO}_{4}\) molecules to form \(\mathrm{H}_{6} \mathrm{P}_{4} \mathrm{O}_{13}\).

Ultrapure germanium, like silicon, is used in semiconductors. Germanium of "ordinary" purity is prepared by the high-temperature reduction of \(\mathrm{GeO}_{2}\) with carbon. The Ge is converted to \(\mathrm{GeCl}_{4}\) by treatment with \(\mathrm{Cl}_{2}\) and then purified by distillation; \(\mathrm{GeCl}_{4}\) is then hydrolyzed in water to \(\mathrm{GeO}_{2}\) and reduced to the elemental form with \(\mathrm{H}_{2}\). The element is then zone refined. Write a balanced chemical equation for each of the chemical transformations in the course of forming ultrapure Ge from \(\mathrm{GeO}_{2}\).

When aluminum replaces up to half of the silicon atoms in \(\mathrm{SiO}_{2}\), a mineral class called feldspars result. The feldspars are the most abundant rock-forming minerals, comprising about \(50 \%\) of the minerals in Earth's crust. Orthoclase is a feldspar in which Al replaces one-fourth of the Si atoms of \(\mathrm{SiO}_{2},\) and charge balance is completed by \(\mathrm{K}^{+}\) ions. Determine the chemical formula for orthoclase.

Hydrogen gas has a higher fuel value than natural gas on a mass basis but not on a volume basis. Thus, hydrogen is not competitive with natural gas as a fuel transported long distances through pipelines. Calculate the heats of combustion of \(\mathrm{H}_{2}\) and \(\mathrm{CH}_{4}\) (the principal component of natural gas) (a) per mole of each, (b) per gram of each, \((\mathbf{c})\) per cubic meter of each at STP. Assume \(\mathrm{H}_{2} \mathrm{O}(l)\) as a product.

One method proposed for removing \(\mathrm{SO}_{2}\) from the flue gases of power plants involves scrubbing with an alkali solid such as calcium carbonate to form calcium sulfite and carbon dioxide gas. (a) Write a balanced chemical equation for the reaction. (b) What mass of \(\mathrm{CaCO}_{3}\) would be required to remove the \(\mathrm{SO}_{2}\) formed by burning \(1000 \mathrm{~kg}\) of coal containing \(8.0 \% \mathrm{~S}\) by mass? \((\mathbf{c})\) What volume of \(\mathrm{CO}_{2}\) is formed under standard temperature and pressure? Assume that all reactions are \(100 \%\) efficient.

The maximum allowable concentration of \(\mathrm{H}_{2} \mathrm{~S}(g)\) in air is \(20 \mathrm{mg}\) per kilogram of air ( 20 ppm by mass). How many grams of FeS would be required to react with hydrochloric acid to produce this concentration at \(101.3 \mathrm{kPa}\) and \(25^{\circ} \mathrm{C}\) in an average room measuring \(3.5 \mathrm{~m} \times 6.0 \mathrm{~m} \times 2.5 \mathrm{~m} ?\) (Under these conditions, the average molar mass of air is \(29.0 \mathrm{~g} / \mathrm{mol} .)\)

The standard heats of formation of \(\mathrm{H}_{2} \mathrm{O}(g), \mathrm{H}_{2} \mathrm{~S}(g), \mathrm{H}_{2} \mathrm{Se}(g)\), and \(\mathrm{H}_{2} \mathrm{Te}(g)\) are \(-241.8,-20.17,+29.7,\) and \(+99.6 \mathrm{~kJ} /\) mol, respectively. The enthalpies necessary to convert the elements in their standard states to one mole of gaseous atoms are \(248,277,227,\) and \(197 \mathrm{~kJ} / \mathrm{mol}\) of atoms for \(\mathrm{O}, \mathrm{S},\) Se, and Te, respectively. The enthalpy for dissociation of \(\mathrm{H}_{2}\) is \(436 \mathrm{~kJ} / \mathrm{mol}\). Calculate the average \(\mathrm{H}-\mathrm{O}, \mathrm{H}-\mathrm{S}, \mathrm{H}-\mathrm{Se}\), and \(\mathrm{H}-\) Te bond enthalpies, and comment on their trend.

Manganese silicide has the empirical formula MnSi and melts at \(1280^{\circ} \mathrm{C}\). It is insoluble in water but does dissolve in aqueous HF. (a) What type of compound do you expect MnSi to be: metallic, molecular, covalent- network, or ionic? (b) Write a likely balanced chemical equation for the reaction of MnSi with concentrated aqueous HF.

Both dimethylhydrazine, \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NNH}_{2},\) and methylhydrazine, \(\mathrm{CH}_{3} \mathrm{NHNH}_{2},\) have been used as rocket fuels. When dinitrogen tetroxide \(\left(\mathrm{N}_{2} \mathrm{O}_{4}\right)\) is used as the oxidizer, the products are \(\mathrm{H}_{2} \mathrm{O}, \mathrm{CO}_{2},\) and \(\mathrm{N}_{2} .\) If the thrust of the rocket depends on the volume of the products produced, which of the substituted hydrazines produces a greater thrust per gram total mass of oxidizer plus fuel? (Assume that both fuels generate the same temperature and that \(\mathrm{H}_{2} \mathrm{O}(g)\) is formed.)

Borazine, \((\mathrm{BH})_{3}(\mathrm{NH})_{3},\) is an analog of \(\mathrm{C}_{6} \mathrm{H}_{6}\), benzene. It can be prepared from the reaction of diborane with ammonia, with hydrogen as another product; or from lithium borohydride and ammonium chloride, with lithium chloride and hydrogen as the other products. (a) Write balanced chemical equations for the production of borazine using both synthetic methods. (b) Draw the Lewis dot structure of borazine. (c) How many grams of borazine can be prepared from \(2.00 \mathrm{~L}\) of ammonia at STP, assuming diborane is in excess?