Problem 1
What are the formal oxidation states of \(\mathrm{N}\) or \(\mathrm{P}\) in the following species? (a) \(\mathrm{N}_{2} ;(\mathrm{b})\left[\mathrm{NO}_{3}\right]^{-} ;(\mathrm{c})\left[\mathrm{NO}_{2}\right]^{-}\) (d) \(\mathrm{NO}_{2} ;\) (e) \(\mathrm{NO} ;(\mathrm{f}) \mathrm{NH}_{3} ;(\mathrm{g}) \mathrm{NH}_{2} \mathrm{OH} ;(\mathrm{h}) \mathrm{P}_{4} ;(\mathrm{i})\left[\mathrm{PO}_{4}\right]^{3-}\) (j) \(P_{4} O_{6} ;(k) P_{4} O_{10}\)
Problem 3
Give a brief account of allotropy among the group 15 elements.
Problem 4
Write equations for the reactions of (a) water with \(\mathrm{Ca}_{3} \mathrm{P}_{2}\) (b) aqueous \(\mathrm{NaOH}\) with \(\mathrm{NH}_{4} \mathrm{Cl}\); (c) aqueous \(\mathrm{NH}_{3}\) with \(\mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2} ;(\mathrm{d}) \mathrm{AsH}_{3}\) with an excess of \(\mathrm{I}_{2}\) in neutral aqueous solution; (c) \(\mathrm{PH}_{3}\) with \(\mathrm{KNH}_{2}\) in liquid \(\mathrm{NH}_{3}\)
Problem 6
If \((\text { at } 298 \mathrm{K}) \mathrm{p} K_{\mathrm{b}}\) for \(\mathrm{NH}_{3}\) is \(4.75,\) show that \(\mathrm{p} K_{\mathrm{a}}\) for \(\left[\mathrm{NH}_{4}\right]^{+}\) is 9.25.
Problem 7
Give the relevant half-equations for the oxidation of \(\mathrm{NH}_{2} \mathrm{OH}\) to \(\mathrm{HNO}_{3}\) by \(\left[\mathrm{BrO}_{3}\right]^{-},\) and write a balanced equation for the overall process.
Problem 8
(a) Write a balanced equation for the preparation of \(\mathrm{NaN}_{3}\) from \(\mathrm{NaNH}_{2}\) with \(\mathrm{NaNO}_{3}\) (b) Suggest a route for preparing the precursor \(\mathrm{NaNH}_{2}\) (c) How might NaN react with \(\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}\) in aqueous solution?
Problem 9
(a) We noted that \(\left[\mathrm{N}_{3}\right]^{-}\) is isoelectronic with \(\mathrm{CO}_{2}\), Give three other species that are also isoelectronic with \(\left[\mathrm{N}_{3}\right]^{-}\) (b) Describe the bonding in \(\left[\mathrm{N}_{3}\right]^{-}\) in terms of an \(\mathrm{MO}\) picture.
Problem 13
(a) Discuss structural variation among the phosphorus(III) and phosphorus(V) halides, indicating where stereochemical non-rigidity is possible. (b) On what basis is it appropriate to compare the lattice of \(\left[\mathrm{PCl}_{4}\right]\left[\mathrm{PCl}_{6}\right]\) with that of \(\mathrm{CsCl}\) ?
Problem 17
Draw the structures of the possible isomers of \(\left[\mathrm{PCl}_{2} \mathrm{F}_{3}(\mathrm{CN})\right]^{-},\) and state how many fluorine environments there are based on the structures you have drawn. At room temperature, the \(^{19} \mathrm{F}\) NMR spectra of \(\mathrm{CH}_{2} \mathrm{Cl}_{2}\) solutions of two of the isomers exhibit two signals, while the spectrum of the third isomer shows only one signal. Account for these observations.
Problem 18
Suggest products for the reactions between (a) \(\mathrm{SbCl}_{5}\) and \(\mathrm{PCl}_{5} ;(\mathrm{b}) \mathrm{KF}\) and \(\mathrm{AsF}_{5} ;(\mathrm{c}) \mathrm{NOF}\) and \(\mathrm{SbF}_{5} ;(\mathrm{d}) \mathrm{HF}\) and \(\mathrm{SbF}_{5}\)
