Problem 19 - Chemistry The Molecular Science

Question

Write a balanced equation to represent (a) the reduction of \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) with carbon monoxide in a blast fumace. (b) the production of hydrogen gas when hydrochloric acid reacts with an iron nail.

Step-by-Step Solution

Answer

(a) \(\mathrm{Fe}_{2} \mathrm{O}_{3} + 3 \mathrm{CO} \rightarrow 2 \mathrm{Fe} + 3 \mathrm{CO}_{2}\); (b) \(2\mathrm{HCl} + \mathrm{Fe} \rightarrow \mathrm{FeCl}_{2} + \mathrm{H}_{2}\).

Step 1: Identify the Reactants and Products for Reaction (a)

In reaction (a), we are focusing on the reduction of iron(III) oxide, \(\mathrm{Fe}_{2} \mathrm{O}_{3}\), with carbon monoxide, \(\mathrm{CO}\). The main reduction product is iron, \(\mathrm{Fe}\), while \(\mathrm{CO}\) is oxidized to form carbon dioxide, \(\mathrm{CO}_{2}\).

Step 2: Write the Unbalanced Equation for Reaction (a)

The unbalanced chemical equation for reaction (a) is: \[ \mathrm{Fe}_{2} \mathrm{O}_{3} + \mathrm{CO} \rightarrow \mathrm{Fe} + \mathrm{CO}_{2} \]

Step 3: Balance the Equation for Reaction (a)

Now, balance the equation by adjusting the coefficients. Balance iron first: \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) gives 2 iron atoms. Then balance the carbon and oxygen: \[ \mathrm{Fe}_{2} \mathrm{O}_{3} + 3 \mathrm{CO} \rightarrow 2 \mathrm{Fe} + 3 \mathrm{CO}_{2} \]

Step 4: Identify the Reactants and Products for Reaction (b)

In reaction (b), hydrochloric acid, \(\mathrm{HCl}\), reacts with iron to produce iron chloride, \(\mathrm{FeCl}_2\), and hydrogen gas, \(\mathrm{H}_2\).

Step 5: Write the Unbalanced Equation for Reaction (b)

The initial unbalanced chemical equation for this reaction is: \[ 2\mathrm{HCl} + \mathrm{Fe} \rightarrow \mathrm{FeCl}_{2} + \mathrm{H}_{2} \]

Step 6: Balance the Equation for Reaction (b)

The coefficients are correct for the balanced state after checking that both sides have equivalent amounts of each element. Therefore, the balanced equation is: \[ 2\mathrm{HCl} + \mathrm{Fe} \rightarrow \mathrm{FeCl}_{2} + \mathrm{H}_{2} \]

Key Concepts

Reduction-Oxidation Reactions

Reduction-Oxidation reactions, or redox reactions for short, are chemical processes where one substance loses electrons and another gains electrons. Here's a simple way to remember it:

• Oxidation: When a substance loses electrons, it's oxidized.
• Reduction: When a substance gains electrons, it's reduced.

In reaction (a), the process involves the reduction of iron(III) oxide, \(\mathrm{Fe}_{2} \mathrm{O}_{3}\), and the oxidation of carbon monoxide, \(\mathrm{CO}\).
The chemical equation shows \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) gaining electrons (and hence being reduced) to form iron, \(\mathrm{Fe}\), while \(\mathrm{CO}\) loses electrons (being oxidized) to form carbon dioxide, \(\mathrm{CO}_{2}\).
When balancing redox reactions, focus on ensuring that the loss and gain of electrons cancel out so that the overall charge and number of atoms stay consistent on both sides of the equation.
This is why we end up with a balanced equation of: \[\mathrm{Fe}_{2} \mathrm{O}_{3} + 3 \mathrm{CO} \rightarrow 2 \mathrm{Fe} + 3 \mathrm{CO}_{2}\]

Blast Furnace Chemistry

Blast furnace chemistry is essential in the extraction of iron from its ores, particularly iron oxides. A blast furnace is a huge steel stack lined with refractory brick. It's charged with iron ore, pellets, sinters, and coke, which act as the reducing agent.
During this process, carbon in the form of coke combines with oxygen to form carbon monoxide (\(\mathrm{CO}\)). This \(\mathrm{CO}\) acts to reduce the iron ore and produce molten iron, while being itself oxidized to carbon dioxide (\(\mathrm{CO}_{2}\)).

• Step 1: The carbon reacts with oxygen in the air to form \(\mathrm{CO}\).
• Step 2: \(\mathrm{CO}\) reduces the iron ore to \(\mathrm{Fe}\).
• Step 3: The product, \(\mathrm{Fe}\), melts and collects at the bottom of the furnace.

This transformation is crucial for iron production, providing approximately 90% of the world's iron. Understanding how blast furnace chemistry works is not only important for production but also for improving efficiency and reducing emissions.

Hydrogen Gas Production

Hydrogen gas production through chemical reactions is an interesting application of redox processes. For reaction (b), when hydrochloric acid (\(\mathrm{HCl}\)) reacts with an iron nail, hydrogen gas is released.
In this reaction:

• \(\mathrm{HCl}\) donates its hydrogen ion \(\mathrm{H}^+\), which gets reduced by gaining electrons to form \(\mathrm{H}_2\) gas.
• Iron (\(\mathrm{Fe}\)) serves as the reducing agent, forming \(\mathrm{FeCl}_2\), and losing electrons in the process.

The balanced equation here is:\[2\mathrm{HCl} + \mathrm{Fe} \rightarrow \mathrm{FeCl}_{2} + \mathrm{H}_{2}\]It's a straightforward redox reaction where the loss and gain of electrons are balanced, leading to the clear production of hydrogen gas.
This process is not only fascinating in a laboratory setting but also has real-world applications, especially in industries where hydrogen is a critical component.