Question 4

Iron is an important transition metal.

Three of the stages in the extraction and purification of iron using the carbonyl process are:

Stage 1: iron(III) oxide is reduced by heating with $H2\text{H}_2$ to produce impure iron:

\text{Fe}_2\text{O}_3(\text{s}) + 3\text{H}_2(\text{g)} \rightarrow 2\text{Fe}(\text{s}) + 3\text{H}_2\text{O}(\text{g)}

Stage 2: the impure iron is reacted with $CO\text{CO}$ to produce iron pentacarbonyl:

\text{Fe}(\text{s}) + 5\text{CO}(\text{g)} \rightleftharpoons \text{Fe(CO)}_5(\text{g)}

Stage 3: $Fe(CO)5\text{Fe(CO)}_5$ is decomposed by heating to produce pure iron:

\text{Fe(CO)}_5(\text{g)} \rightarrow \text{Fe}(\text{s}) + 5\text{CO}(\text{g)}

State why the reaction in Stage 1 is described as reduction.

Suggest why a low temperature produces a high yield of $Fe(CO)5\text{Fe(CO)}_5$ in Stage 2.

Iron has a melting point of $1538∘C1538^{\circ}\text{C}$ and is a good conductor of electricity.

Describe the arrangement and charges of the particles in metallic iron.

Explain, in terms of its structure, why iron is malleable and is a good conductor of electricity.