Chapter 20

What is the primary reducing agent in the production of iron from its ores? Write a balanced chemical equation for this reduction process.

Why is limestone necessary in the blast furnace reduction of iron ore?

What is the difference between pig iron and cast iron?

Explain the purpose of each of these materials in the blast-furnace conversion of iron ore to iron. (a) Air (b) Limestone (c) Coke

Identify what is produced by each of these processes or operations. (a) Blast furnace (b) Basic oxygen process (c) Roasting

Identify a typical use for \(\mathrm{Cr}, \mathrm{Cu}, \mathrm{Fe}, \mathrm{Au},\) and \(\mathrm{Ag}\).

Name three transition metals that are found "free" in nature.

What is the lanthanide contraction? Why does it occur?

In general, how do the atomic radii change across the first transition series (Period 4)?

Distinguish between (a) a monodentate and a bidentate ligand. (b) a cis and a trans isomer. (c) a coordination compound and a coordination complex ion. (d) a geometric and an optical isomer.

Define these words or phrases and give an example for each. (a) Coordination compound (b) Complex ion (c) Ligand (d) Chelate (e) Bidentate ligand

Write electron configurations for the common oxidation states of (a) silver. (b) gold.

Write electron configurations for the \(2+\) ions of (a) iron. (b) copper. (c) chromium.

Which Period 4 transition-metal ions are isoelectronic with (a) \(\mathrm{Zn}^{2+}\) (b) \(\mathrm{Mn}^{2+}\) (c) \(\mathrm{Cr}^{3+}\) (d) \(\mathrm{Fe}^{3+}\)

Write a balanced equation to represent (a) the reduction of \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) with carbon monoxide in a blast fumace. (b) the production of hydrogen gas when hydrochloric acid reacts with an iron nail.

Write a balanced equation to represent (a) the roasting of \(\mathrm{Cu}_{2} \mathrm{~S}\) to copper metal. (b) the reduction of \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) with aluminum.

Balance this redox reaction (in acidic solution). $$ \mathrm{Fe}(\mathrm{s})+\mathrm{NO}_{3}^{-}(\mathrm{aq}) \longrightarrow \mathrm{Fe}^{3+}(\mathrm{aq})+\mathrm{NO}_{2}(\mathrm{~g}) $$

Balance this redox reaction (in acidic solution). $$ \mathrm{Cu}(\mathrm{s})+\mathrm{NO}_{3}^{-}(\mathrm{aq}) \longrightarrow \mathrm{Cu}^{2+}(\mathrm{aq})+\mathrm{NO}_{2}(\mathrm{~g}) $$

Determine the oxidation state (oxidation number) of the transition metal in each compound. $$ \begin{array}{ll} \text { (a) } \mathrm{V}_{2} \mathrm{O}_{5} & \text { (b) } \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7} \\ \text { (c) } \mathrm{MnO}_{2} & \text { (d) } \mathrm{OsO}_{4} \end{array} $$

Determine the oxidation state of iron in \(\mathrm{KFe}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\). Explain your answer.

Explain why the atomic radii of transition metals vary less across a period than do main-group elements.

Explain why the radii of Period 5 and Period 6 transition elements are nearly the same.

Predict which element in the pair has the larger atomic radius. (a) Cu or Ag (b) \(\mathrm{T} \mathrm{i}\) or \(\mathrm{Cr}\) (c) W or \(\mathrm{Hg}\)

Predict which element in the pair has the smaller atomic radius. (a) \(\mathrm{Pt}\) or \(\mathrm{Ni}\) (b) Ti or \(\mathrm{Ni}\) (c) \(Z r\) or \(\mathrm{Rh}\)

Describe how extracting iron from its ore is done by reduction, but producing steel is an oxidation process.

Describe the major differences between cast iron and steel.

Describe the production of steel by the basic oxygen process.

Identify the elements used, in addition to iron and carbon, to make (a) duriron. (b) high-speed steel. (c) permanent magnets.

Describe how the composition of brass differs from that of bronze.

Describe native copper. Why is it important?

Describe how blister copper is electrorefined.

Explain what a reducing sugar is in terms of aqueous copper chemistry.

Compare the action of concentrated nitric acid on silver with that on gold.

Describe how the percent of gold in its alloys is expressed in carats.

Describe why other metals are added to silver and gold.

Give the oxidation state (number) of chromium in each of these compounds. (a) \(\mathrm{FeCr}_{2} \mathrm{O}_{4}\) (b) \(\mathrm{Cr}_{2} \mathrm{O}_{5}\) (c) \(\mathrm{K}_{2}\left[\mathrm{CrF}_{6}\right]\) (d) \(\left[\mathrm{Cr}(\mathrm{en})_{3}\right] \mathrm{Cl}_{2}\)

In a complex ion, a central \(\mathrm{Cr}^{3+}\) ion is bonded to two ammonia molecules, three water molecules, and a hydroxide ion. (a) Give the formula and charge of the complex ion. (b) Identify a single counter ion that could be used with the complex ion to form an uncharged compound.

In a complex ion, a central ruthenium ion, \(\mathrm{Ru}(\mathrm{III})\), is bonded to six ammonia molecules. (a) Give the formula and net charge for this complex ion. (b) How many chloride ions are needed to balance the net charge on this complex ion? (c) Write the formula for the compound formed by this complex ion and the chloride ions that are not part of it.

Consider the complex ion \(\left[\mathrm{Co}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{2} \mathrm{Cl}_{2}\right]^{3-}\). (a) Identify the ligands and their charges (if any). (b) Determine the charge on the central metal ion. (c) Determine the formula and charge of the complex ion in which the \(\mathrm{C}_{2} \mathrm{O}_{4}^{2-}\) ions were replaced by \(\mathrm{NH}_{3}\) molecules.

Consider the complex ion \(\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{2}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2} \mathrm{Br}_{2}\right]^{+}\). (a) Identify the ligands and their charges (if any). (b) Determine the charge on the central metal ion. (c) Dctermine the formula of the sulfate salt of this cation.

Determine the charge of the central metal ion in each case. (a) \(\left[\mathrm{Zn}\left(\mathrm{H}_{2} \mathrm{O}\right)_{3}(\mathrm{OH})\right]^{+}\) (b) \(\left[\mathrm{Pt}\left(\mathrm{NH}_{3}\right)_{3} \mathrm{Cl}_{3}\right]^{+}\) (c) \(\left[\mathrm{Cr}(\mathrm{CN})_{6}\right]^{3-}\)

For coordination compounds \(\mathrm{Na}_{3}\left[\mathrm{Ir} \mathrm{Cl}_{6}\right]\) and \(\left[\mathrm{Mo}(\mathrm{CO})_{4}\right] \mathrm{Br}_{2},\) identify in cach case (a) the ligands. (b) the central metal ion and its charge. (c) the formula and charge of the complex ion. (d) any ions not part of the complex ion.

Give the coordination number of the central metal ion in (a) \(\left[\mathrm{Pt}(\mathrm{en})_{2}\right]^{2+}\) (b) \(\left[\mathrm{Cu}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{2}\right]^{2-}\).

Give the coordination number of the central metal ion in (a) \(\left[\mathrm{Ni}(\mathrm{cn})_{2}\left(\mathrm{NH}_{3}\right)_{2}\right]^{2+}\). (b) \(\left[\mathrm{Fe}(\mathrm{cn})\left(\mathrm{C}_{2} \mathrm{O}_{4}\right) \mathrm{Cl}_{2}\right]^{-}\)

Write a structural formula for the coordination compound \(\left[\mathrm{Cr}(\mathrm{en})\left(\mathrm{NH}_{3}\right)_{2} \mathrm{I}_{2}\right],\) and give the coordination number for the central \(\mathrm{Cr}^{2+}\) ion.

Give the formula of each of these coordination compounds formed with \(\mathrm{Pt}^{2+}\) (a) Two ammonia molecules and two bromide ions (b) One ethylenediamine molecule and two nitrite ions, \(\mathrm{NO}_{2}^{-}\) (c) One chloride ion, one bromide ion, and two ammonia molecules

Give the charge on the central metal ion in each of these. (a) \(\left[\mathrm{VCl}_{6}\right]^{4-}\) (b) \(\left[\mathrm{Sc}\left(\mathrm{H}_{2} \mathrm{O}\right)_{3} \mathrm{Cl}_{3}\right]\) (c) \(\left[\mathrm{Mn}(\mathrm{NO})(\mathrm{CN})_{5}\right]^{3-}\) (d) \(\left[\mathrm{Ni}(\mathrm{en})_{2}\left(\mathrm{NH}_{3}\right)_{2}\right]^{2+}\)

Identify the coordination number of the metal ion in these coordination complexes. (a) \(\left[\mathrm{FeCl}_{4}\right]^{-}\) (b) \(\left[\mathrm{PtBr}_{4}\right]^{2-}\) (c) \(\left[\mathrm{Mn}(\mathrm{en})_{3}\right]^{2+}\) (d) \(\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{5} \mathrm{H}_{2} \mathrm{O}\right]^{3+}\)

Using structural formulas, show how the carbonate ion can be either a monodentate or bidentate ligand to a transition-metal cation.

Write the formula for (a) potassium diaquadioxalatocobaltate(III). (b) diamminetriaquahydroxochromium(II) nitrate. (c) ammonium tetrachlorocuprate(II).