(b) If a limestone sculp- ture were treated to form a surface layer of calcium sul- fate, would this help to slow down the effects of acid rain? Explain.

Verified step by step guidance

1. Understand the composition of limestone, which is primarily calcium carbonate (CaCO₃).
2. Recognize that acid rain is typically composed of sulfuric acid (H₂SO₄) and nitric acid (HNO₃), which react with calcium carbonate to form calcium sulfate (CaSO₄), carbon dioxide (CO₂), and water (H₂O).
3. Consider the chemical reaction: CaCO₃ + H₂SO₄ → CaSO₄ + CO₂ + H₂O.
4. Evaluate the properties of calcium sulfate, which is less soluble in water compared to calcium carbonate, potentially forming a protective layer.
5. Conclude that a surface layer of calcium sulfate could slow down the effects of acid rain by reducing the rate at which the underlying calcium carbonate is exposed to acidic conditions.

Key Concepts

Acid Rain

Acid rain is precipitation that has a lower pH than normal, typically due to the presence of sulfuric and nitric acids formed from atmospheric pollutants. It can cause significant damage to buildings, sculptures, and natural landscapes by reacting with minerals in the materials, leading to erosion and degradation. Understanding the chemical composition of acid rain is crucial for evaluating its effects on various substances.

Calcium Sulfate

Calcium sulfate is a chemical compound that can form a protective layer on surfaces when applied. This layer can act as a barrier, potentially reducing the direct exposure of the underlying material to acidic components in rain. Its effectiveness in slowing down the deterioration of limestone sculptures depends on its ability to withstand acidic conditions and its adherence to the surface.

Chemical Weathering

Chemical weathering refers to the process by which rocks and minerals undergo chemical reactions that alter their composition and structure, often due to environmental factors like acid rain. In the case of limestone, which is primarily composed of calcium carbonate, acid rain can lead to the dissolution of the rock, resulting in loss of material. Understanding this process is essential for assessing how protective treatments like calcium sulfate can mitigate damage.