Question

Iron is produced from iron ore by reaction with carbon monoxide: \(\mathrm{Fe}_{2} \mathrm{O}_{3}(s)+\mathrm{CO}(g) \longrightarrow \mathrm{Fe}(s)+\mathrm{CO}_{2}(g)\) (a) Balance the chemical equation. (b) Classify the reaction as a precipitation, neutralization, or redox reaction.

Short answer

(a) \( \text{Fe}_2\text{O}_3 + 3\, \text{CO} \rightarrow 2\, \text{Fe} + 3\, \text{CO}_2 \); (b) Redox reaction.

Step-by-step solution

Write the Unbalanced Equation

The given chemical equation is \( \text{Fe}_2\text{O}_3(s) + \text{CO}(g) \rightarrow \text{Fe}(s) + \text{CO}_2(g) \). We need to balance the number of atoms of each element on both sides.

Balance Iron (Fe) Atoms

There are 2 iron atoms in \( \text{Fe}_2\text{O}_3 \) on the left side. To balance the iron atoms, we place a coefficient of 2 before \( \text{Fe} \) on the right side, resulting in \( \text{Fe}_2\text{O}_3(s) + \text{CO}(g) \rightarrow 2\, \text{Fe}(s) + \text{CO}_2(g) \).

Balance Oxygen (O) Atoms

There are 3 oxygen atoms in \( \text{Fe}_2\text{O}_3 \) on the left and 2 oxygen atoms in \( \text{CO}_2 \) on the right. We balance the oxygen by adjusting \( \text{CO} \) on the left side to 3 \( \text{CO} \), resulting in \( \text{Fe}_2\text{O}_3(s) + 3\, \text{CO}(g) \rightarrow 2\, \text{Fe}(s) + 3\, \text{CO}_2(g) \).

Balance Carbon (C) Atoms

There are 3 carbon atoms in the \( 3\, \text{CO} \) on the left side and 3 carbon atoms in the 3 \( \text{CO}_2 \) on the right side, which are already balanced.

Verify the Equation

Ensure that all atoms are balanced. On both sides, there are 2 Fe atoms, 3 C atoms, and 6 O atoms. The equation remains \( \text{Fe}_2\text{O}_3(s) + 3\, \text{CO}(g) \rightarrow 2\, \text{Fe}(s) + 3\, \text{CO}_2(g) \).

Classify the Reaction

Analyze the reaction type. This is a redox reaction because there is a transfer of electrons: iron is reduced and carbon is oxidized.

Key concepts

Redox Reactions

In a redox reaction, two processes occur simultaneously: reduction and oxidation. Reduction involves the gain of electrons, resulting in a decrease in oxidation state. Oxidation, conversely, is the loss of electrons, increasing the oxidation state. Together, these processes involve the transfer of electrons between reactants.
For example, in the reaction: \( \text{Fe}_2\text{O}_3 + 3\, \text{CO} \rightarrow 2\, \text{Fe} + 3\, \text{CO}_2\), iron is reduced as the iron ore \( \text{Fe}_2\text{O}_3 \) turns into metallic iron \( \text{Fe} \).
This means it gains electrons. Meanwhile, carbon in carbon monoxide \( \text{CO} \) gets oxidized to \( \text{CO}_2 \), losing electrons in the process. This electron transfer confirms that this reaction is a redox reaction. Understanding redox reactions is crucial as they are a fundamental part of many biological and chemical processes, including respiration and combustion.

• Reduction: Gain of electrons; decrease in oxidation state.
• Oxidation: Loss of electrons; increase in oxidation state.
• Redox Reaction: Combination of reduction and oxidation.

Chemical Reaction Classification

Chemical reactions can be classified into various types based on the changes that occur. The main types include:

• Precipitation Reactions: These occur when two solutions combine to form an insoluble solid called a precipitate.
• Neutralization Reactions: These involve an acid and a base reacting to form water and a salt.
• Redox Reactions: As discussed earlier, these feature electron transfer from one reactant to another.

Each type of reaction has its unique characteristics and balancing equations for them can involve different strategies. In our exercise, the reaction \(\text{Fe}_2\text{O}_3 + 3\, \text{CO} \rightarrow 2\, \text{Fe} + 3\, \text{CO}_2\) involves electron transfer, indicating it's a type of redox reaction. Understanding these classifications helps identify the process and predict the products in various chemical settings.

Stoichiometry

Stoichiometry is the art and science of calculating the quantities of reactants and products in chemical reactions. By using a balanced chemical equation, like \(\text{Fe}_2\text{O}_3 + 3\, \text{CO} \rightarrow 2\, \text{Fe} + 3\, \text{CO}_2\), stoichiometry helps determine the amount of each substance consumed or produced.
To balance a chemical equation, you ensure the same number of each type of atom appears on both sides of the equation, a reflection of the law of conservation of mass. In the reaction process:

• Calculate how many moles of each component participate in the reaction.
• Use coefficients to balance atoms of each element.
• Predict amounts of products from a given amount of reactants.

For instance, from balancing \( \text{Fe}_2\text{O}_3 + 3\, \text{CO} \rightarrow 2\, \text{Fe} + 3\, \text{CO}_2 \), we see that three moles of carbon monoxide react with one mole of iron(III) oxide to produce two moles of iron. This quantitative approach is essential for industrial applications, ensuring efficient and cost-effective chemical manufacturing.