Question

Iron ores, usually oxides of iron, are converted to the pure metal by reaction in a blast furnace with carbon (coke). The carbon is first reacted with air to form carbon monoxide, which in turn reacts with the iron oxides as follows: $$\mathrm{Fe}_{2} \mathrm{O}_{3}(s)+3 \mathrm{CO}(g) \rightarrow 2 \mathrm{Fe}(l)+3 \mathrm{CO}_{2}(g)$$ Identify the atoms that are oxidized and reduced, and specify the oxidizing and reducing agents.

Short answer

In the given reaction, iron (Fe) atoms are reduced as their oxidation state increases from +3 in Fe2O3 to 0 in elemental Fe. Conversely, carbon (C) atoms in CO are oxidized as their oxidation state increases from +2 in CO to +4 in CO2. The oxidizing agent is Fe2O3, and the reducing agent is CO.

Step-by-step solution

Determine the oxidation states of the atoms in the equation

First, let's find the oxidation states for all the atoms present in the given chemical equation: \(\mathrm{Fe}_{2} \mathrm{O}_{3}(s)+3 \mathrm{CO}(g) \rightarrow 2 \mathrm{Fe}(l)+3 \mathrm{CO}_{2}(g)\) Oxidation states: Fe: 0 (in elemental form, as Fe) O: -2 (in oxide form, as O in Fe2O3) C: +2 (in CO) C: +4 (in CO2)

Identify the atoms that are oxidized and reduced

Now that we have the oxidation states of all the atoms, we can identify the atoms undergoing oxidation and reduction. An atom is said to be oxidized if its oxidation state increases, and it's reduced if its oxidation state decreases. 1. The oxidation state of Fe increases from +3 (in Fe2O3) to 0 (in elemental Fe). Therefore, Fe is reduced during the reaction. 2. The oxidation state of C increases from +2 (in CO) to +4 (in CO2). Therefore, C is oxidized during the reaction.

Specify the oxidizing and reducing agents

Lastly, we need to specify the oxidizing and reducing agents in the reaction. The oxidizing agent is the substance that causes the oxidation, which means it gets reduced in the process, whereas the reducing agent is the substance that causes the reduction, and gets oxidized in the process. 1. Fe2O3 acts as the oxidizing agent since it causes the carbon in CO to be oxidized and itself gets reduced (Fe changes from +3 to 0). 2. CO acts as the reducing agent as it causes the Fe in Fe2O3 to be reduced and itself gets oxidized (C changes from +2 to +4). To summarize, the iron atoms are reduced, and the carbon atoms in CO are oxidized. The oxidizing agent is Fe2O3, and the reducing agent is CO.

Key concepts

Oxidation States

In a chemical reaction, oxidation states (or oxidation numbers) help us track the transfer of electrons. Understanding these states is crucial for identifying which atoms undergo oxidation and reduction.
The oxidation state is a theoretical charge that an atom would have if all bonds were ionic. It provides a way to track the gain or loss of electrons in a reaction.

• Elemental form: The oxidation state is always 0. For example, Fe (iron) in pure metallic form has an oxidation state of 0.
• Oxygen generally has an oxidation state of -2. This is seen in oxides like Fe₂O₃.
• Carbon can have different oxidation states, such as +2 in carbon monoxide (CO) and +4 in carbon dioxide (CO₂).

In the given reaction:

• Fe₂O₃: Iron (Fe) has an oxidation state of +3 because it is bonded to oxygen.
• In CO, carbon holds a +2 oxidation state.

Understanding these states help us identify the elements that are oxidized or reduced.

Oxidizing Agent

In our reaction, the oxidizing agent is the substance that gains electrons, causing another substance to lose electrons, or be oxidized. Basically, it is reduced during the reaction.

In the equation for iron extraction, Fe₂O₃ acts as the oxidizing agent.

• Fe in Fe₂O₃ gains electrons and its oxidation state decreases from +3 to 0, which means it is reduced.
• This reduction allows carbon to increase in oxidation state, hence oxidized.

Thus, Fe₂O₃, by accepting electrons, facilitates the oxidation of carbon in CO and is therefore the oxidizing agent.

Reducing Agent

Conversely, the reducing agent donates electrons and causes another substance to be reduced. During this process, it is oxidized.
Using our example reaction:

• Carbon monoxide (CO) is the reducing agent. It donates electrons to the iron atoms in Fe₂O₃, reducing them.
• This process increases carbon's own oxidation state from +2 to +4 as it gets converted into CO₂.

By losing electrons, CO facilitates the reduction of Fe₂O₃, distinguishing it as the reducing agent in the iron extraction process.

Iron Extraction

Iron extraction is a fascinating process of converting iron oxides to pure iron using carbon, mainly in the form of coke. This conversion happens in a blast furnace.
During this process:

• Iron oxides such as hematite (Fe₂O₃) are mixed with carbon (coke).
• The reaction with carbon monoxide (produced from coke and air) reduces the iron oxide into liquid iron.

The chemical reaction involved can be summarized as: Fe₂O₃ + 3CO → 2Fe + 3CO₂. This reaction highlights the reduction of iron and the oxidation of carbon, demonstrating the interplay of redox reactions crucial for iron extraction.

Chemical Equations

Chemical equations are a symbolic representation of a chemical reaction. They show reactants transforming into products, providing insight into the process occurring.
In the context of iron extraction:

• The reactants are Fe₂O₃ and CO, and the products are Fe and CO₂.
• The equation Fe₂O₃ + 3CO → 2Fe + 3CO₂ is balanced, meaning the number of atoms for each element is the same on both sides, adhering to the law of conservation of mass.

Writing and balancing chemical equations is essential in predicting the products formed in any chemical reaction and understanding how substances interact.