Question

Which of the following is an agent of chemical weathering? A. ice wedging B. burrowing animals C. carbonic acid D. growing tree roots

Short answer

C. Carbonic acid is an agent of chemical weathering.

Step-by-step solution

Identify the Concept

Chemical weathering is the process by which rocks are broken down by chemical reactions. This often involves the alteration of minerals in the rock, usually by water, air, or other chemicals.

Analyze Each Option

Review the options to see which are involved in chemical weathering: - A. Ice wedging: This is a physical weathering process where water freezes in cracks and expands. - B. Burrowing animals: This is a biological process where animals move soil and rocks via physical means. - C. Carbonic acid: This is a chemical weathering agent that forms when carbon dioxide dissolves in water, creating a weak acid that can dissolve specific minerals. - D. Growing tree roots: This is a physical weathering process where roots grow into cracks in rocks and push them apart.

Select the Correct Option

From the analysis, option C, carbonic acid, is identified as the agent of chemical weathering since it involves a chemical reaction altering the mineral composition of rocks.

Key concepts

Carbonic Acid

In the process of chemical weathering, carbonic acid plays a significant role. This acid is formed when carbon dioxide from the atmosphere dissolves into rainwater, creating a weak acid. Though it might sound fragile, carbonic acid is very effective at breaking down certain types of minerals found in rocks.
For example, carbonic acid can react with minerals like calcite, commonly found in limestone and marble. This interaction slowly dissolves the minerals, contributing to the alteration of the rock's structure. This makes carbonic acid an essential agent in transforming the landscape over long periods.
The effectiveness of carbonic acid in weathering also highlights the profound impact that atmospheric gases have on Earth's surface processes. Understanding carbonic acid's role helps us appreciate the slow and steady change in geology worldwide, showcasing how even weak acids can powerfully shape our planet.

Agents of Weathering

Agents of weathering are forces or processes that break down rocks and minerals at Earth's surface. They are mainly categorized into three types: physical, chemical, and biological weathering.
Physical weathering involves breaking down rocks through physical means like temperature fluctuation, ice wedging, or abrasion by wind or water. It does not alter the chemical composition of the minerals.
Chemical weathering, on the other hand, involves the alteration of the chemical structure of minerals. Besides carbonic acid, other agents involved in chemical weathering include oxygen, which can lead to oxidation, and water, which can facilitate hydrolysis.
Biological weathering involves living organisms. Plants, animals, and microbes can play a role by physically breaking rocks or chemically changing their composition. Together, these agents contribute to the continually changing face of our planet.

Mineral Alteration

Mineral alteration is a crucial component of chemical weathering. It refers to changes in the mineral structure within rocks due to chemical reactions. As minerals interact with air, water, or chemical agents like acids, their original form alters.
A classic example of mineral alteration is the transformation of feldspar minerals into clay. Water interacts with feldspar, slowly breaking it down over time into clay minerals. Another example is the formation of iron oxides from iron-rich minerals like pyroxene or olivine due to oxidation.
These alterations not only weaken rocks but also contribute valuable nutrients to the soil. Understanding mineral alteration provides insight into soil formation and landscape evolution, highlighting the dynamic nature of Earth's geologic processes.

Earth Science Concepts

Earth science is an umbrella term that encompasses several fields related to understanding Earth’s processes, including geology, meteorology, oceanography, and environmental science. These disciplines help us understand how weathering processes like chemical weathering influence Earth's surface.
Key concepts in earth science include the rock cycle, the cycling of water and gases, and the role of energy in driving processes. Weathering plays an integral part in the rock cycle by breaking down rocks, which provide materials for soil and sediment formation.
This interconnectedness reflects the complex systems at work, where processes like chemical weathering are not isolated events but parts of broader environmental interactions. Grasping these earth science concepts is essential for appreciating the delicate balance and long-term evolution of our planet.