Problem 28
Comment on the following observations. (a) In its complexes, Co(III) forms strong bonds to \(O\) - and \(N\) -donor ligands, moderately strong bonds to \(P\) -donor ligands, but only weak bonds to \(A s\) -donor ligands. (b) The values of \(\log K\) for the reaction: \(\mathrm{Zn}^{2+}(\mathrm{aq})+\mathrm{X}^{-} \rightleftharpoons[\mathrm{ZnX}]^{+}(\mathrm{aq})\) are 0.7 for \(X=F,-0.2\) for \(X=C 1,-0.6\) for \(X=B r\) and -1.3 for \(X=I\) (c) Phosphine adducts of \(\mathrm{Cr}(\mathrm{III})\) halides can be prepared, but crystallographic studies reveal very long \(\mathrm{Cr}-\mathrm{P}\) bonds (e.g. \(247 \mathrm{pm}\) ).
Problem 34
(a) For \(\left[\mathrm{Pd}(\mathrm{CN})_{4}\right]^{2-},\) a value of \(\log \beta_{4}\) of 62.3 (at \(298 \mathrm{K}\) in aqueous medium) has been determined. To what equilibrium process does this value refer? (b) For the equilibrium: \(\operatorname{Pd}(\mathrm{CN})_{2}(\mathrm{s})+2 \mathrm{CN}^{-}(\mathrm{aq}) \rightleftharpoons\left[\mathrm{Pd}(\mathrm{CN})_{4}\right]^{2-}\) the value of \(\log K\) is \(20.8 .\) Use this value and the data in part (a) to determine \(K_{\mathrm{sp}}\) for \(\mathrm{Pd}(\mathrm{CN})_{2}\).
