You are working with an artist who has been commissioned to make a sculpture for a big city in the eastern United States. The artist is wondering what material to use to make her sculpture because she has heard that acid rain in the eastern United States might destroy it over time. You take samples of granite, marble, bronze, and other materials, and place them outdoors for a long time in the big city. You periodically examine the appearance and measure the mass of the samples. (a) What observations would lead you to conclude that one or more of the materials are well- suited for the sculpture?

Key Concepts

Acid Rain

Acid rain is precipitation that has a lower pH than normal rainwater, primarily due to the presence of sulfuric and nitric acids formed from atmospheric pollutants. It can cause significant damage to various materials, particularly those that are calcareous, like marble and limestone, leading to corrosion and structural degradation. Understanding the chemical composition of acid rain is crucial for predicting how different materials will react when exposed to it over time.

Material Durability

Material durability refers to the ability of a substance to withstand environmental factors without significant degradation. In the context of sculpture materials, factors such as weathering, corrosion, and physical wear are important. Evaluating the durability of granite, marble, and bronze involves observing changes in appearance, mass loss, and structural integrity after exposure to elements like acid rain.

Corrosion Mechanisms

Corrosion mechanisms describe the processes through which materials deteriorate due to chemical reactions with their environment. For metals like bronze, corrosion can occur through oxidation or reaction with acids, while stone materials may undergo dissolution or physical weathering. Identifying the specific corrosion mechanisms affecting each material will help determine which is best suited for long-term outdoor exposure in an acidic environment.