Problem 1
An absorption in an IR spectrum of an organic compound comes at \(3100 \mathrm{cm}^{-1}\) and is assigned to an \(\mathrm{X}-\mathrm{H}\) bond where \(\mathrm{X}=\mathrm{C}, \mathrm{O}\) or \(\mathrm{N}\). Determine the shift in this band upon deuteration of the \(X-H\) bond for (a) \(\mathrm{X}=^{12} \mathrm{C}\), \((b) X=^{16} O\) and \((\mathrm{c}) \mathrm{X}=^{14} \mathrm{N}\)
Problem 2
Why are kinetic isotope effects useful for reactions involving \(\mathrm{C}-\mathrm{H}\) bonds but are not likely to be of significant use in studying reactions involving \(^{12} \mathrm{C}=\mathrm{O}\) and \(^{13} \mathrm{C}=\mathrm{O}\) labelled compounds?
Problem 3
Which of the following metal ions might be reduced to the respective metal by \(\mathrm{H}_{2}:(\mathrm{a}) \mathrm{Cu}^{2+}\) (b) \(\mathrm{Zn}^{2+} ;(\mathrm{c}) \mathrm{Fe}^{2+}\) \((\mathrm{d}) \mathrm{Ni}^{2+}\) \(;\) (e) \(\mathrm{Mn}^{2+}\) ? Conversely, which of the following metals would react with dilute sulfuric acid to generate \(\mathrm{H}_{2}:(\mathrm{a}) \mathrm{Mg}\) (b) Ag; (c) Ca; (d) \(\mathrm{Zn} ;\) (e) \(\mathrm{Cr} ?\)
Problem 7
What is the oxidation state of nitrogen in (a) \(\mathrm{NH}_{3}\) (b) \(\left[\mathrm{NH}_{4}\right]^{+},(\mathrm{c}) \mathrm{N}_{2} \mathrm{H}_{4}\) and \((\mathrm{d})\left[\mathrm{NH}_{2}\right]^{-} ?\)
Problem 9
Discuss what is meant by hydrogen bonding and how it may influence (a) the boiling points and (b) the solid state structures of hydrides of some of the \(p\) -block elements.
Problem 11
For each of the following molecules \(\mathrm{EH}_{n}:\) state whether the \(\mathrm{E}-\mathrm{H}\) bond is polar and if \(\mathrm{so},\) show in which direction the dipole moment acts; and state whether the molecule is polar and if so, indicate the direction of the resultant molecular dipole moment: (a) \(\mathrm{CH}_{4}\) (b) \(\mathrm{H}_{2} \mathrm{O}\) (c) \(\mathrm{BH}_{3}\) (d) \(\mathrm{NH}_{3}\) (e) \(\mathrm{SiH}_{4}\) (f) \(\mathrm{HCl}\) \((\mathrm{g}) \mathrm{H}_{2} \mathrm{Se}\)
Problem 12
Suggest products for the following reactions: (a) electrolysis of molten \(\mathrm{KBr}\) (b) electrolysis of aqueous \(\mathrm{NaCl}\) (c) \(\mathrm{BaO}_{2}\) with aqueous \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (d) passage of \(\mathrm{H}_{2}\) over hot \(\mathrm{PbO}\) (e) addition of a small amount of \(\mathrm{MnO}_{2}\) to \(\mathrm{H}_{2} \mathrm{O}_{2}\) (f) reaction of \(\mathrm{H}_{2} \mathrm{O}_{2}\) with acidified KI solution.
Problem 15
Suggest how lattice energy effects might be used to explain why the stabilities of potassium, rubidium and caesium superoxides are greater than that of sodium superoxide, and why lithium usually forms the oxide \(\mathrm{Li}_{2} \mathrm{O}\) rather than the peroxide or superoxide.
Problem 17
Suggest products for the following reactions which are not necessarily balanced on the left-hand side: (a) \(\operatorname{Sr} \mathrm{CO}_{3}(\mathrm{s})^{1560}\) (b) \(\mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow\) (c) \(\operatorname{Be}(\mathrm{OH})_{2}(\mathrm{s})+\operatorname{excess}[\mathrm{OH}]^{-}(\mathrm{aq}) \rightarrow\) (d) \(\operatorname{Mg}(\mathrm{OH})_{2}(\mathrm{s})+\mathrm{HCl}(\mathrm{aq}) \rightarrow\) (e) \(\operatorname{CaF}_{2}(\mathrm{s})+\mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{conc}) \rightarrow\) (f) \(\mathrm{CaH}_{2}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow\)
Problem 18
The first members of periodic groups are often noted for their 'anomalous behaviour'. Discuss some of the chemical properties of (a) lithium and (b) beryllium that would support this statement.
