Explain the electrolysis of molten lead(II) iodide, including relevant definitions and chemical equations.

a) A conductor is a substance that allows electric current or heat to flow through it easily.

b) An electrode is a solid electrical conductor through which electricity enters or leaves an electrolyte.

c) An electrolyte is a substance that, when dissolved in a solvent or melted, produces mobile ions and conducts electricity.

d) Electrolysis is the process of using electrical energy to drive a non-spontaneous chemical reaction, typically decomposing an ionic compound by passing an electric current through it.

a) When molten lead(II) iodide undergoes electrolysis, it decomposes. The $\text{Pb}^{2+}$ ions migrate to the cathode and are reduced to molten lead metal, while the $\text{I}^{-}$ ions migrate to the anode and are oxidized to iodine gas.

b) Solid lead(II) iodide does not conduct electricity because its ions ($\text{Pb}^{2+}$ and $\text{I}^{-}$) are held in fixed positions within the crystal lattice and are not free to move to carry charge.

c) The equations for the reactions are:
*i) At the cathode (reduction): $\text{Pb}^{2+}(l) + 2\text{e}^{-} \to \text{Pb}(l)$ *ii) At the anode (oxidation): $2\text{I}^{-}(l) \to \text{I}_2(g) + 2\text{e}^{-}$ d) It is important to carry out this experiment in a fume chamber because iodine gas ($\text{I}_2$) is produced at the anode, and iodine vapor is toxic and irritating to the respiratory system.

a) Allotropy is the property of some chemical elements to exist in two or more different forms, called allotropes, in the same physical state. These forms have different structural arrangements of atoms, leading to different physical and chemical properties.

b) Two examples of naturally occurring allotropes of carbon are diamond and graphite.

c) i) Z is a wash bottle containing a solution of potassium hydroxide ($\text{KOH}$) or sodium hydroxide ($\text{NaOH}$). Its role is to absorb the carbon dioxide ($\text{CO}_2$) produced along with carbon monoxide ($\text{CO}$) from the decomposition of oxalic acid, thus purifying the carbon monoxide gas.