What is meant by a transition element?
Sketch the form of a $3d_{z^2}$ orbital.
Explain the meaning of a heterogeneous catalyst.
Describe how a heterogeneous catalyst works in a reaction.
Manganese(VII) oxide, $\text{Mn}_2\text{O}_7$, may be prepared by treating $\text{KMnO}_4$ with concentrated sulfuric acid (reaction 1). $\text{Mn}_2\text{O}_7$ decomposes readily at room temperature to give manganese(IV) oxide and a colourless diatomic gas (reaction 2). Write equations for both reactions described.
Give the ionic equation, and identify the type of reaction, for the reaction of $[\text{Mn(H}_2\text{O})_6]^{2+}$ with $\text{NaOH}(aq)$.
Give the ionic equation, and identify the type of reaction, for the reaction of $[\text{Mn(H}_2\text{O})_6]^{2+}$ with concentrated $\text{HCl}$.
Table 2.1 lists relevant electrode potentials for some electrode reactions. Suggest the formula of the manganese species formed when $\text{Mn}^{2+}(aq)$ reacts with $\text{Cl}_2$. State the type of reaction.