Question

Write reactions to show how the nitric and sulfuric acids in acid rain react with marble and limestone. (Both marble and limestone are primarily calcium carbonate.)

Short answer

The chemical reactions of nitric acid (HNO₃) and sulfuric acid (H₂SO₄) with calcium carbonate (CaCO₃), the primary component of marble and limestone, are as follows: Nitric acid reaction: \(CaCO_3 + 2HNO_3 \rightarrow Ca(NO_3)_2 + H_2O + CO_2\) Sulfuric acid reaction: \(CaCO_3 + H_2SO_4 \rightarrow CaSO_4 + H_2O + CO_2\)

Step-by-step solution

Nitric Acid Reaction

1. Write the reactants: calcium carbonate (CaCO₃) and nitric acid (HNO₃) \(CaCO_3 + HNO_3\) 2. Since an acid reacts with a carbonate to produce a salt, water, and carbon dioxide, we can write the products as calcium nitrate (Ca(NO₃)₂), water (H₂O), and carbon dioxide (CO₂). 3. Balance the chemical equation: \(CaCO_3 + 2HNO_3 \rightarrow Ca(NO_3)_2 + H_2O + CO_2\) So, the balanced chemical equation for the reaction between calcium carbonate and nitric acid is: \(CaCO_3 + 2HNO_3 \rightarrow Ca(NO_3)_2 + H_2O + CO_2\)

Sulfuric Acid Reaction

1. Write the reactants: calcium carbonate (CaCO₃) and sulfuric acid (H₂SO₄) \(CaCO_3 + H_2SO_4\) 2. Since an acid reacts with a carbonate to produce a salt, water, and carbon dioxide, we can write the products as calcium sulfate (CaSO₄), water (H₂O), and carbon dioxide (CO₂). 3. Balance the chemical equation: \(CaCO_3 + H_2SO_4 \rightarrow CaSO_4 + H_2O + CO_2\) So, the balanced chemical equation for the reaction between calcium carbonate and sulfuric acid is: \(CaCO_3 + H_2SO_4 \rightarrow CaSO_4 + H_2O + CO_2\)

Key concepts

Calcium Carbonate Reaction

Understanding how calcium carbonate reacts with acids is fundamental in studying the effects of acid rain on structures like marble and limestone. Calcium carbonate ((CaCO_3)) is a common material found in rocks such as marble and limestone. When acid rain comes into contact with these structures, it results in a chemical reaction. This reaction forms water ((H_2O)), carbon dioxide ((CO_2)), and a corresponding salt. For example, when calcium carbonate reacts with nitric acid ((HNO_3)), calcium nitrate ((Ca(NO_3)_2)) is formed. Similarly, reacting with sulfuric acid ((H_2SO_4)) forms calcium sulfate ((CaSO_4)). During the reaction, a single molecule of (CaCO_3) can neutralize two acidic molecules, but the exact products depend on the specific acid involved.

Nitric Acid Reaction

Nitric acid ((HNO_3)) is a strong acid that reacts vigorously with bases and effectively dissolves metals. When (HNO_3) encounters calcium carbonate, it leads to the formation of calcium nitrate, water, and carbon dioxide. This reaction is a great example of an acid-carbonate reaction, which always produces a salt, water, and (CO_2) gas. An important aspect of understanding this reaction is observing the release of carbon dioxide, a visible effervescence that signifies the reaction is taking place.

Balancing the equation for the reaction ensures that the law of conservation of mass is satisfied. It's critical to remember that the amount of acid used will be double the amount of calcium carbonate due to the stoichiometry of the reactants and products involved.

Sulfuric Acid Reaction

Sulfuric acid ((H_2SO_4)) is another potent acid often found in acid rain. When sulfuric acid comes into contact with calcium carbonate, a similar type of reaction occurs as with nitric acid. The result of the reaction is calcium sulfate, water, and carbon dioxide.

The effervescence of carbon dioxide is a clear indication of the reaction. This type of reaction is central to environmental science and is critical for students to understand when studying the effects of acid rain on ancient and modern carbonate structures. With sulfuric acid, each molecule can react with a molecule of calcium carbonate, showcasing a one-to-one stoichiometry, simpler than the reaction with nitric acid.

Chemical Equation Balancing

The concept of balancing chemical equations is a cornerstone of chemistry. It requires that one ensure the same number of each type of atom is present on both the reactant and product sides of the equation. This conservation of mass is a foundational chemical principle.

When balancing the reaction between calcium carbonate and an acid, it is crucial to count each atom of carbon, hydrogen, nitrogen, sulfur, oxygen, and calcium. The coefficients of the reactants and products are then adjusted to balance these atoms. This often involves understanding the stoichiometry of the reaction, which is the ratio in which the reactants combine to form products. For instance, with nitric acid, you need to account for the two hydrogen atoms required to balance the equation, which is why its coefficient is two in the balanced equation with calcium carbonate.