Problem 2
Comment on the variation in oxidation states of the first row metals. Why are Sc and Zn not classed as transition metals?
Problem 3
In the complex \(\left[\mathrm{Ti}\left(\mathrm{BH}_{4}\right)_{3}\left(\mathrm{McOCH}_{2} \mathrm{CH}_{2} \mathrm{OMc}\right)\right],\) the Ti(III) centre is 8 -coordinate. Suggest modes of coordination for the ligands.
Problem 4
Comment on each of the following observations. (a) \(\mathrm{Li}_{2} \mathrm{TiO}_{3}\) forms a continuous range of solid solutions with \(\mathrm{MgO}\) (b) When \(\mathrm{TiCl}_{3}\) is heated with concentrated aqueous \(\mathrm{NaOH}, \mathrm{H}_{2}\) is evolved.
Problem 13
Give cquations for the following reactions: (a) heating Fe with \(\mathrm{Cl}_{2} ;\) (b) heating Fe with \(\mathrm{I}_{2} ;\) (c) solid \(\mathrm{FeSO}_{4}\) with concentrated \(\mathrm{H}_{2} \mathrm{SO}_{4} ;\) (d) aqueous \(\mathrm{Fe}^{3+}\) with \([\mathrm{SCN}]^{-} ;(\mathrm{e})\) aqucous \(\mathrm{Fe}^{3+}\) with \(\mathrm{K}_{2} \mathrm{C}_{2} \mathrm{O}_{4} ;\) (f) \(\mathrm{FeO}\) with dilute \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (g) aqueous \(\mathrm{FeSO}_{4}\) and \(\mathrm{NaOH}\).
Problem 14
How would you attempt to (a) estimate the crystal field stabilization energy of \(\mathrm{FeF}_{2},\) and (b) determine the overall stability constant of \(\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}\) in aqueous solution given that the overall formation constant for \(\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{2+}\) is \(10^{5},\) and: \begin{aligned} \left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}(\mathrm{aq})+\mathrm{e}^{-} \rightleftharpoons\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{2+}(\mathrm{aq}) & \\ E^{0}=&+0.11 \mathrm{V} \end{aligned}
Problem 16
Give explanations for the following observations. (a) The complex \(\left[\mathrm{Co}(\mathrm{en})_{2} \mathrm{Cl}_{2}\right]_{2}\left[\mathrm{CoCl}_{4}\right]\) has a room temperature magnetic moment of \(3.71 \mu_{\mathrm{eff}}\) (b) The room temperature magnetic moment of \(\left[\mathrm{CoI}_{4}\right]^{2-}\) (e.g. \(5.01 \mu_{\mathrm{B}}\) for the \(\left[\mathrm{Et}_{4} \mathrm{N}\right]^{+}\) salt) is larger than that of salts of \(\left[\mathrm{CoCl}_{4}\right]^{2-}\)
Problem 17
(a) When \([\mathrm{CN}]^{-}\) is added to aqueous \(\mathrm{Ni}^{2+}\) ions, a green precipitate forms; if excess \(\mathrm{KCN}\) is added, the precipitate dissolves to give a yellow solution and at high concentrations of \([\mathrm{CN}]^{-},\) the solution becomes red. Suggest an explanation for these observations. (b) If the yellow compound from part (a) is isolated and reacted with Na in liquid \(\mathrm{NH}_{3},\) a red, air-sensitive, diamagnetic product can be isolated. Suggest its identity.
Problem 18
Treatment of an aqueous solution of \(\mathrm{NiCl}_{2}\) with \(\mathrm{H}_{2} \mathrm{NCHPhCHPhNH}_{2}\) gives a blue complex \(\left(\mu_{\mathrm{eff}}=3.30 \mu_{\mathrm{B}}\right)\) which loses \(\mathrm{H}_{2} \mathrm{O}\) on heating to form a yellow, diamagnetic compound. Suggest explanations for these observations and comment on possible isomerism in the yellow species.
Problem 19
Give equations for the following reactions: (a) aqueous \(\mathrm{NaOH}\) with \(\mathrm{CuSO}_{4} ;(\mathrm{b}) \mathrm{CuO}\) with \(\mathrm{Cu}\) in concentrated HCl at reflux; (c) Cu with concentrated \(\mathrm{HNO}_{3}\) (d) addition of aqueous \(\mathrm{NH}_{3}\) to a precipitate of \(\mathrm{Cu}(\mathrm{OH})_{2}\) (e) \(\mathrm{ZnSO}_{4}\) with aqueous NaOH followed by addition of excess \(\mathrm{NaOH} ;(\mathrm{f}) \mathrm{ZnS}\) with dilute \(\mathrm{HCl}\)
Problem 21
Copper(II) chloride is not completely reduced by \(\mathrm{SO}_{2}\) in concentrated HCl solution. Suggest an explanation for this observation and state how you would try to establish if the explanation is correct.
