Question Format: Long
Three common ores of iron are $\mathrm{FeO}, \mathrm{Fe}_{2} \mathrm{O}_{3}$, and $\mathrm{Fe}_{3} \mathrm{O}_{4}$. Iron ores are often reduced to elemental iron by heating in the presence of carbon monoxide. These iron ores are all brittle and do not conduct electricity in their solid form.
(a) Identify the oxidation number of the iron atoms in each of the three ores.
(b) Choose one of the iron ores and write a balanced chemical equation to show its reduction reaction with carbon monoxide.
(c) Considering the types of bonding involved, how and why do the properties of the ores differ from those of pure iron?

Carbon steel is an interstitial alloy of iron with a small amount of carbon which has greater strength and density than pure iron but maintains the metallic properties of iron.
(d) Is the combination of iron with carbon to form steel a chemical or physical change? Explain your answer.
(e) In a box like the one shown here, draw a representation of the structure of this alloy. Use $10-20$ iron atoms and 4-6 carbon atoms in your structure.
$\mathrm{O}=\mathrm{Fe}$
- $=\mathrm{C}$
(f) As the percent carbon increases in steel, the ductility of the steel decreases. Explain why this might occur.

Question

Question Format: Long
Three common ores of iron are $\mathrm{FeO}, \mathrm{Fe}_{2} \mathrm{O}_{3}$, and $\mathrm{Fe}_{3} \mathrm{O}_{4}$. Iron ores are often reduced to elemental iron by heating in the presence of carbon monoxide. These iron ores are all brittle and do not conduct electricity in their solid form.
(a) Identify the oxidation number of the iron atoms in each of the three ores.
(b) Choose one of the iron ores and write a balanced chemical equation to show its reduction reaction with carbon monoxide.
(c) Considering the types of bonding involved, how and why do the properties of the ores differ from those of pure iron?

Carbon steel is an interstitial alloy of iron with a small amount of carbon which has greater strength and density than pure iron but maintains the metallic properties of iron.
(d) Is the combination of iron with carbon to form steel a chemical or physical change? Explain your answer.
(e) In a box like the one shown here, draw a representation of the structure of this alloy. Use $10-20$ iron atoms and 4-6 carbon atoms in your structure.
$\mathrm{O}=\mathrm{Fe}$
- $=\mathrm{C}$
(f) As the percent carbon increases in steel, the ductility of the steel decreases. Explain why this might occur.

Accepted Answer

∻Solution∻ ‖ 1 ⋮ **Identify oxidation numbers**: The oxidation number of iron in $FeO$ is +2, in $Fe_2O_3$ is +3, and in $Fe_3O_4$ is +2 and +3 (averaging to +2.67). ‖‖ 2 ⋮ **Balanced chemical equation**: For the reduction of $Fe_2O_3$ with carbon monoxide, the balanced equation is: $$ 2 \mathrm{Fe}_2\mathrm{O}_3 + 3 \mathrm{CO} \rightarrow 4 \mathrm{Fe} + 3 \mathrm{CO}_2 $$ ‖‖ 3 ⋮ **Properties comparison**: Iron ores are ionic compounds with strong electrostatic forces, making them brittle and non-conductive, while pure iron has metallic bonding, allowing it to conduct electricity and be malleable. ‖‖ 4 ⋮ **Chemical vs Physical change**: The combination of iron with carbon to form steel is a chemical change because it results in the formation of a new substance with different properties. ‖‖ 5 ⋮ **Structure representation**: A simple representation of the alloy could be shown as a grid with iron atoms (O) and carbon atoms (C) interspersed, e.g., OOOOCOOOOCCOOO. ‖‖ 6 ⋮ **Ductility explanation**: As the percent carbon increases in steel, the ductility decreases because carbon atoms create interstitial sites that hinder the movement of dislocations, making the material more brittle. ‖ ∻Answer∻ ⚹ The oxidation numbers of iron in the ores are +2 for $FeO$, +3 for $Fe_2O_3$, and a mix of +2 and +3 for $Fe_3O_4$. The reduction of $Fe_2O_3$ with CO is a chemical reaction, and the properties of ores differ from pure iron due to bonding types. The combination of iron and carbon is a chemical change, and increased carbon reduces ductility. ⚹ ∻Key Concept∻ ⚹ Oxidation states and reduction reactions of iron ores, properties of alloys, and changes during alloy formation ⚹ ∻Explanation∻ ⚹ Understanding oxidation states helps in identifying the reactivity of iron ores, while the properties of alloys like steel are crucial for their applications in engineering. ⚹◊What is the role of carbon in the reduction of iron ores, and how does it affect the properties of the resulting steel?⍭ Generate me a similar question◊

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