Problem 13
The lanthanide contraction is given as an explanation for the fact that the \(6^{\text {th }}\) period transition metals have (a) lower densities than the \(5^{\text {th }}\) period transition elements. (b) atomic radii similar to the \(5^{\text {th }}\) period transition elements. (c) lower melting points than the \(5^{\text {th }}\) period transition elements.
Problem 14
Describe how the atomic radii of the transition metals change across a period and rationalize this change based on electronic structure.
Problem 15
What is the most common form that iron is found in the Earth's crust? (a) free metal (b) iron oxide (c) iron sulfide (d) iron silicate
Problem 16
In the reaction $$\begin{aligned} \operatorname{CuFeS}_{2}(s)+3 \operatorname{CuCl}_{2}(\text { aq }) & \longrightarrow \operatorname{CuCl}(s)+\operatorname{FeCl}_{2}(a q)+2 S(s) \end{aligned}$$ what element is oxidized and what element is reduced? (a) Sulfur is reduced, iron is oxidized. (b) Copper is reduced, sulfur is oxidized. (c) Sulfur is reduced, copper is oxidized. (d) This is not a redox reaction.
Problem 17
In the pyrometallurgy of iron, what two species serve as reducing agents?
Problem 18
Lime (CaO) is usually added to the blast furnace in the metallurgy of iron where it reacts with impurities present in iron ore. What of the following best describes its function? (a) \(\mathrm{CaO}\) acts as an oxidizing agent. (b) CaO acts as a reducing agent. (c) \(\mathrm{CaO}\) acts as an acid. (d) \(\mathrm{CaO}\) acts as a base.
Problem 20
One of the following nitrogen compounds or ions is not capable of serving as a ligand: \(\mathrm{NH}_{4}^{+}, \mathrm{NH}_{3}\) \(\mathrm{NH}_{2}^{-} .\) Identify this species, and explain your answer.
Problem 23
Give the oxidation number of the metal ion in each of the following compounds. (a) \(\left[\mathrm{Mn}\left(\mathrm{NH}_{3}\right)_{6}\right] \mathrm{SO}_{4}\) (c) \(\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{2}\right] \mathrm{Cl}\) (b) \(\mathrm{K}_{3}\left[\mathrm{Co}(\mathrm{CN})_{6}\right]\) (d) \(\mathrm{Cr}(\mathrm{en})_{2} \mathrm{Cl}_{2}\)
Problem 24
Give the oxidation number of the metal ion in each of the following compounds. (a) \(\left[\mathrm{Mn}\left(\mathrm{NH}_{3}\right)_{6}\right] \mathrm{SO}_{4}\) (c) \(\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{2}\right] \mathrm{Cl}\) (b) \(\mathrm{K}_{3}\left[\mathrm{Co}(\mathrm{CN})_{6}\right]\) (d) \(\mathrm{Cr}(\mathrm{en})_{2} \mathrm{Cl}_{2}\)
Problem 25
Give the formula of a complex constructed from one \(\mathrm{Ni}^{2+}\) ion, one ethylenediamine ligand, three ammonia molecules, and one w$$\left[\mathrm{Ni}(\mathrm{en})\left(\mathrm{NH}_{3}\right)_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{2+}$$ter molecule. Is the complex neutral or is it charged? If charged, give the charge.
