Problem 42 - Chemistry and Chemical Reactivity

Question

The beautiful red mineral rhodochrosite is manganese(II) carbonate. Write an overall, balanced equation for the reaction of the mineral with hydrochloric acid, and name the products.

Step-by-Step Solution

Answer

The balanced equation is \(\text{MnCO}_3 + 2\text{HCl} \rightarrow \text{MnCl}_2 + \text{CO}_2 + \text{H}_2\text{O}\). Products: manganese(II) chloride, carbon dioxide, water.

Step 1: Identify Reactants

The reactants in the given problem are manganese(II) carbonate, which has the chemical formula \(\text{MnCO}_3\), and hydrochloric acid, \(\text{HCl}\).

Step 2: Predict Products

When \(\text{MnCO}_3\) reacts with \(\text{HCl}\), the products formed are manganese(II) chloride \(\text{MnCl}_2\), carbon dioxide \(\text{CO}_2\), and water \(\text{H}_2\text{O}\).

Step 3: Write the Unbalanced Equation

Based on the reactants and predicted products, the unbalanced chemical equation is: \[\text{MnCO}_3 + \text{HCl} \rightarrow \text{MnCl}_2 + \text{CO}_2 + \text{H}_2\text{O}\]

Step 4: Balance the Chemical Equation

To balance the equation, ensure that the number of atoms of each element on the reactant side equals the number on the product side. The balanced chemical equation is: \[\text{MnCO}_3 + 2\text{HCl} \rightarrow \text{MnCl}_2 + \text{CO}_2 + \text{H}_2\text{O}\]

Step 5: Name the Products

The products of the reaction are manganese(II) chloride (\(\text{MnCl}_2\)), carbon dioxide (\(\text{CO}_2\)), and water (\(\text{H}_2\text{O}\)).

Key Concepts

Balancing Chemical Equations

Balancing chemical equations is crucial in chemistry as it ensures that the conservation of mass is satisfied. When you write a chemical equation, the number of atoms for each element must be the same on both sides of the reaction. To balance an equation, follow these steps:

1. **List Each Element:** Count the number of each type of atom in the reactants and products.
2. **Adjust Coefficients:** Use coefficients to adjust the number of atoms on each side. For example, if you have two chlorines in the product but only one in the reactants, you may need to add a \(2\) in front of the molecule containing chlorine.
3. **Balance Charge:** If needed, balance ionic charges by adding coefficients to molecules with charge.

In our example, manganese(II) carbonate \((\text{MnCO}_3)\) reacts with hydrochloric acid \(\text{HCl}\). Initially, the equation \(\text{MnCO}_3 + \text{HCl} \rightarrow \text{MnCl}_2 + \text{CO}_2 + \text{H}_2\text{O}\) had too few chlorines in the reactants. Therefore, we balance it by placing a \(2\) in front of \(\text{HCl}\): \[\text{MnCO}_3 + 2\text{HCl} \rightarrow \text{MnCl}_2 + \text{CO}_2 + \text{H}_2\text{O}\] This ensures the conservation of mass and follows the law that atoms are neither created nor destroyed.

Inorganic Chemistry

Inorganic chemistry focuses on inorganic compounds, which include minerals, metals, and organometallic compounds. Inorganic compounds often involve ionic bonding between metals and non-metals.

**Compounds in Our Reaction:**

• Manganese(II) carbonate \(\text{MnCO}_3\) is a common mineral and represents the carbonate group of minerals.
• Hydrochloric acid \(\text{HCl}\) is a strong acid used frequently in inorganic synthesis and reactions.
• Products like manganese(II) chloride \(\text{MnCl}_2\), carbon dioxide \(\text{CO}_2\), and water \(\text{H}_2\text{O}\) are typical products of reactions involving acids and carbonates.

These compounds showcase classic inorganic chemistry reactions where metal carbonates react with acids to form salts, gases, and water. Understanding these reactions helps illustrate processes like mineral weathering, acid-neutralization, and industrial synthesis.

Naming Chemical Compounds

Naming chemical compounds systematically is essential for clear communication in chemistry. Each compound has a unique name that identifies its composition and sometimes its structure.

**Naming Rules in Our Reaction:**

• **Manganese(II) carbonate \(\text{MnCO}_3\):** Here, "Manganese(II)" indicates the oxidation state of the manganese ion, and "carbonate" refers to the polyatomic ion \(\text{CO}_3^{2-}\).
• **Hydrochloric acid \(\text{HCl}\):** Derived from hydrogen chloride gas dissolved in water. It is a binary acid, identified by the "hydro-" prefix and "-ic" suffix.
• **Manganese(II) chloride \(\text{MnCl}_2\):** Again, "Manganese(II)" specifies the +2 oxidation state, and "chloride" designates the anion part \(\text{Cl}^-\).
• **Carbon dioxide \(\text{CO}_2\):** A simple covalent compound using the name of the elements with appropriate prefixes to indicate the number of atoms, though names like carbon dioxide are exceptions often memorized.
• **Water \(\text{H}_2\text{O}\):** Because of its ubiquity, water retains its common name, though it could be called "dihydrogen monoxide."

Knowing these naming conventions enables clear identification and communication of complex chemical interactions and aids in writing and interpreting chemical equations correctly.