Problem 32
From each of the following pairs, choose the complex that absorbs light at a longer wavelength: (a) \(\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{2+}\) \(\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+} ;(\mathrm{b})\left[\mathrm{FeF}_{6}\right]^{3-},\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-} ;\) (c) \(\left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+},\left[\mathrm{CuCl}_{4}\right]^{2-}\)
Problem 33
A solution made by dissolving \(0.875 \mathrm{~g}\) of \(\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{3}\) in \(25.0 \mathrm{~g}\) of water freezes at \(-0.56^{\circ} \mathrm{C}\). Calculate the number of moles of ions produced when 1 mole of \(\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{3}\) is dissolved in water, and suggest a structure for the complex ion present in this compound.
Problem 35
Plastocyanin, a copper-containing protein found in photosynthetic systems, is involved in electron transport, with the copper ion switching between the +1 and +2 oxidation states. The copper ion is coordinated with two histidine residues, a cysteine residue, and a methionine residue in a tetrahedral configuration. How does the crystal field splitting \((\Delta)\) change between these two oxidation states?
Problem 36
Define the terms labile complex and inert complex.
Problem 37
Explain why a thermodynamically stable species may be chemically reactive and a thermodynamically unstable species may be unreactive.
Problem 38
Oxalic acid \(\left(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}\right)\) is sometimes used to clean rust stains from sinks and bathtubs. Explain the chemistry underlying this cleaning action.
Problem 39
The \(\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-}\) complex is more labile than the \(\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4-}\) complex. Suggest an experiment that would prove that \(\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-}\) is a labile complex.
Problem 40
Aqueous copper(II) sulfate solution is blue in color. When aqueous potassium fluoride is added, a green precipitate is formed. When aqueous potassium chloride is added instead, a bright-green solution is formed. Explain what is happening in these two cases.
Problem 41
When aqueous potassium cyanide is added to a solution of copper(II) sulfate, a white precipitate, soluble in an excess of potassium cyanide, is formed. No precipitate is formed when hydrogen sulfide is bubbled through the solution at this point. Explain.
Problem 42
A concentrated aqueous copper(II) chloride solution is bright green in color. When diluted with water, the solution becomes light blue. Explain.
