Problem 99 - Chemistry: An Atoms-Focused Approach

Question

Marine Chemistry of Iron On the seafloor, solid iron(II) oxide may react with water to form solid \(\mathrm{Fe}_{3} \mathrm{O}_{4}\) and hydrogen gas. a. Write a balanced chemical equation for the reaction. b. When \(\mathrm{CO}_{2}\) is also present, the product of the reaction is methane, not hydrogen. Write a balanced chemical equation for this reaction.

Step-by-Step Solution

Answer

Question: Write the balanced chemical equations for the following reactions: 1. The reaction between solid iron(II) oxide and water to form solid Fe3O4 and hydrogen gas. 2. The reaction between solid iron(II) oxide, water, and CO2 to form methane and any other products. Answer: 1. The balanced chemical equation for the reaction between solid iron(II) oxide and water is: \[3\mathrm{FeO \ (s)} + 2\mathrm{H_{2}O \ (l)} \rightarrow \mathrm{Fe_{3}O_{4} \ (s)} + \mathrm{H_{2} \ (g)}\] 2. The balanced chemical equation for the reaction between solid iron(II) oxide, water, and CO2 to form methane is: \[3\mathrm{FeO \ (s)} + 2\mathrm{H_{2}O \ (l)} + 3\mathrm{CO_{2} \ (g)} \rightarrow 2\mathrm{CH_{4} \ (g)} + \mathrm{Fe_{3}O_{4} \ (s)}\]

Step 1: Write the balanced reaction between iron(II) oxide and water

The unbalanced equation is FeO (s) + H2O (l) -> Fe3O4 (s) + H2 (g) As there are 3 Fe atoms on the right side and only 1 on the left, we need to multiply FeO by 3: 3FeO (s) + H2O (l) -> Fe3O4 (s) + H2 (g) Now, count the oxygen and hydrogen atoms. On the left side, there are 3 O and 2 H, while on the right side, there are 4 O and 2 H. Balance the oxygen with a coefficient of 2 in front of the H2O to have 4 oxygen atoms on each side: 3FeO (s) + 2H2O (l) -> Fe3O4 (s) + H2 (g) The balanced reaction is: \[3\mathrm{FeO \ (s)} + 2\mathrm{H_{2}O \ (l)} \rightarrow \mathrm{Fe_{3}O_{4} \ (s)} + \mathrm{H_{2} \ (g)}\]

Step 2: Write the balanced reaction between iron(II) oxide, water, and CO2 to form methane

The unbalanced equation contains iron(II) oxide (FeO), water (H2O), CO2, and methane (CH4). FeO (s) + H2O (l) + CO2 (g) -> CH4 (g) + ? Since FeO is the source of iron, the possible iron-containing product is Fe3O4, like in the previous reaction. FeO (s) + H2O (l) + CO2 (g) -> CH4 (g) + Fe3O4 (s) Now balance the reaction: 3FeO (s) + 2H2O (l) + 3CO2 (g) -> 2CH4 (g) + Fe3O4 (s) The balanced reaction is: \[3\mathrm{FeO \ (s)} + 2\mathrm{H_{2}O \ (l)} + 3\mathrm{CO_{2} \ (g)} \rightarrow 2\mathrm{CH_{4} \ (g)} + \mathrm{Fe_{3}O_{4} \ (s)}\]

Key Concepts

Iron Oxide Reactions

Iron oxide reactions, especially involving iron(II) oxide ( FeO ), play a significant role in marine chemistry.
When iron(II) oxide comes into contact with water, it undergoes a chemical reaction. This reaction is important on the seafloor. It transitions iron(II) oxide into magnetite ( Fe₃O₄ ) and hydrogen gas ( H₂ ).
- In this particular reaction, iron(II) oxide ( FeO(s) ) reacts with water ( H₂O(l) ). - The products are solid Fe₃O₄ (s) and hydrogen gas ( H₂(g) ). Chemists often explore these reactions to understand how minerals transform underwater.
Factors like temperature and pressure also influence how efficiently these reactions occur in marine environments. This knowledge is crucial for geochemists studying the ocean floor and its compositions.

Balanced Chemical Equation

A balanced chemical equation shows the conservation of mass. This means the same number of each type of atom is present on both sides of a chemical equation.
Let's consider the reaction of iron(II) oxide with water:- Begin with writing the unbalanced equation: FeO (s) + H₂O (l) \( \rightarrow \) Fe₃O₄ (s) + H₂ (g).- Balancing involves adjusting the number of units to equalize each atom type.Here is how we balance this reaction:- **Fe**: There are three iron atoms (Fe) in Fe₃O₄, meaning you need three FeO units on the left side.- **O**: To balance oxygen, consider the total oxygen atoms in Fe₃O₄ (4) and H₂O.- **H**: Place a coefficient of 2 in front of H₂O.The resulted balanced equation is:\[3\mathrm{FeO(s)} + 2\mathrm{H_{2}O(l)} \rightarrow \mathrm{Fe_{3}O_{4}(s)} + \mathrm{H_{2}(g)} \]

Methane Formation

Methane formation involves a shift in products when carbon dioxide (CO₂) is present with iron(II) oxide and water.
The presence of CO₂ alters the outcome of the previous reaction significantly.- Instead of producing hydrogen gas, the reaction outputs methane gas (CH₄).- Methane is a significant contributor to Earth's gaseous resources and helps in studies related to energy and environmental science.In the presence of water and CO₂:- The reactants are iron(II) oxide and carbon dioxide along with water.- After balancing the equation, the correct proportions result in:\[3\mathrm{FeO (s)} + 2\mathrm{H_{2}O (l)} + 3\mathrm{CO_{2} (g)} \rightarrow 2\mathrm{CH_{4} (g)} + \mathrm{Fe_{3}O_{4} (s)} \]This reaction is a fantastic example of the interplay between geological processes and atmospheric chemistry. Understanding such interactions aids in comprehending the broader cycles involving carbon and their environmental impacts. By balancing these equations, you can accurately represent and study real-world chemical reactions.