Group 2 nitrates break down when heated. Describe how the thermal stability of Group 2 nitrates changes as proton number increases. Explain your answer.
Copper(II) nitrate decomposes in a similar way to Group 2 nitrates. Write an equation for the decomposition of $\text{Cu(NO}_3)_2$.
$\text{Cu(NO}_3)_2$ is mixed with water to make solution A. Fig. 1.1 shows some reactions of solution A. Complete Table 1.1 to give the formula and colour of each copper-containing species present in A, B, C and D.
$\text{EDTA}^{4-}$ is a polydentate ligand. Explain what is meant by a polydentate ligand.
Group 2 metal ions can form complexes similar to those of transition elements. A solution of $\text{EDTA}^{4-}$ is added to water containing $[\text{Ca(H}_2\text{O)}_6]^{2+}$ to make the new complex $[\text{CaEDTA}]^{2-}$, as shown.\n\nEquilibrium 1:\n$[\text{Ca(H}_2\text{O)}_6]^{2+} + \text{EDTA}^{4-} \rightleftharpoons [\text{CaEDTA}]^{2-} + 6\text{H}_2\text{O}$\n\nOn the structure of $\text{EDTA}^{4-}$ in Fig. 1.2, circle the six atoms that form bonds with the metal ion.
The calcium ions in $[\text{Ca(H}_2\text{O)}_6]^{2+}$ and $[\text{CaEDTA}]^{2-}$ have a coordination number of 6. Explain what is meant by coordination number.
The complex $[\text{CaEDTA}]^{2-}$ can be used to remove toxic metals from the body. Table 1.2 gives the numerical values for the stability constants, $K_{\text{stab}}$, for some metal ions with $\text{EDTA}^{4-}$. An aqueous solution containing $[\text{CaEDTA}]^{2-}$ is added to a solution containing equal concentrations of $\text{Cr}^{3+}$(aq), $\text{Fe}^{3+}$(aq) and $\text{Pb}^{2+}$(aq). The mixture is then left until equilibrium is reached. State the type of reaction when $[\text{CaEDTA}]^{2-}$ reacts with $\text{Cr}^{3+}$(aq), $\text{Fe}^{3+}$(aq) and $\text{Pb}^{2+}$(aq).
Deduce the relative concentrations of $[\text{CrEDTA}]^{-}$, $[\text{FeEDTA}]^{-}$ and $[\text{PbEDTA}]^{2-}$ present in the resulting mixture. Explain your answer.
State the type of reaction when $[\text{CaEDTA}]^{2-}$ reacts with $\text{Cr}^{3+}(aq)$, $\text{Fe}^{3+}(aq)$ and $\text{Pb}^{2+}(aq)$.
Deduce the relative concentrations of $[\text{CrEDTA}]^{-}$, $[\text{FeEDTA}]^{-}$ and $[\text{PbEDTA}]^{2-}$ present in the resulting mixture. Explain your answer.
The number of moles of water of crystallisation in a hydrated ionic salt can be found by titration using aqueous $\text{EDTA}^{4-}$ ions with a suitable indicator. \n\n$0.255\,\text{g}$ of hydrated chromium(III) sulfate, $\text{Cr}_2(\text{SO}_4)_3\cdot n\text{H}_2\text{O}$, is dissolved in water and made up to $100\,\text{cm}^3$ in a volumetric flask. \n\n$25.0\,\text{cm}^3$ of this solution requires $26.2\,\text{cm}^3$ of $0.00800\,\text{mol dm}^{-3}$ aqueous $\text{EDTA}^{4-}$ ions to reach the end-point. \n\nThe reaction is shown below:\n\n$[\text{Cr}(\text{H}_2\text{O})_6]^{3+} + \text{EDTA}^{4-} \rightarrow [\text{CrEDTA}]^{-} + 6\text{H}_2\text{O}$\n\nUse the data to calculate the value of $n$ in the formula $\text{Cr}_2(\text{SO}_4)_3\cdot n\text{H}_2\text{O}$. Show your working.
A solution of $\text{Cr}^{3+}(aq)$ and a solution of $\text{Fe}^{3+}(aq)$ have different colours. Explain why the two complexes have different colours.