Explain what is meant by the term polydentate ligand.
When EDTA$^{4-}$ is added to a solution of $[\text{Cd(H}_2\text{O)}_6]^{2+}$, a new complex, $[\text{CdEDTA}]^{2-}$, is formed. Equilibrium 1 is: $[\text{Cd(H}_2\text{O)}_6]^{2+} + \text{EDTA}^{4-} \rightleftharpoons [\text{CdEDTA}]^{2-} + 6\text{H}_2\text{O}$. On the EDTA$^{4-}$ structure, circle the six atoms that bond with the metal ion.
Write an expression for the stability constant, $K_{\text{stab}1}$, for equilibrium 1, and give its units.
$K_{\text{eq}4}$ is the equilibrium constant for equilibrium 4. Write it in terms of $K_{\text{stab}2}$ and $K_{\text{stab}3}$.
Calculate the value of the standard Gibbs free energy change, $\Delta G^\circ$, for equilibrium 4 at $298\,\text{K}$.
State how $\Delta G^\circ$ changes as the temperature rises. Explain your answer.