Explain why transition elements can act as catalysts.
State the oxidation state and the coordination number of titanium in $[\text{TiCl}_4(\text{diars})_2]$, where diars is a neutral bidentate ligand.
Draw three-dimensional diagrams of $[\text{Ag(CN)}_2]^{-}$ and $[\text{Cu(CN)}_4]^{3-}$ in the boxes to show their shapes. Mark one bond angle on each diagram.
Write an expression to represent the stability constant, $K_{\text{stab}}$, for $[\text{Cu(CN)}_4]^{3-}$.
In solution, both $\text{CN}^-$ and $[\text{Cu(CN)}_4]^{3-}$ have concentrations of $0.0010\,\text{mol dm}^{-3}$. Use the expression from (c)(i) together with the value of $K_{\text{stab}}$ to calculate the concentration of $\text{Cu}^+(aq)$ in this solution.
Calculate the amount of $\text{I}_2$ reduced in this titration, in moles.
Calculate how many moles of copper were present in the original alloy piece.
Calculate the percentage of copper present in the alloy.
Suggest why an aqueous solution of $\text{Cu}^{2+}$ is coloured, whereas solid $\text{CuI}$ is white.