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Chemical Weathering: The Breakdown of Rocks Through Chemical Reactions — Reading Comprehension

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Standards

MS-ESS2-1
MS-ESS2-2
RST.6-8.4

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This passage explains chemical weathering processes, aligned with NGSS MS-ESS2-1 (Earth’s systems) and ESS2-2 (surface processes). It covers hydrolysis, oxidation (rust), carbonation (caves), and acid rain impacts. Real-world examples include karst topography, the Statue of Liberty’s patina, and tropical laterite soils. The text meets CCSS.ELA-LITERACY.RST.6-8.4 for technical vocabulary and highlights connections to soil formation, pollution, and climate science.

CONTENT PREVIEW

Chemical weathering occurs when rocks decompose or dissolve due to chemical reactions with water, gases, or biological agents. Unlike mechanical weathering, which breaks rocks into smaller pieces, chemical weathering alters their mineral composition, transforming them into new substances.

Causes of Chemical Weathering

Hydrolysis: Minerals react with water, forming new compounds (e.g., feldspar turning into clay).
Oxidation: Oxygen reacts with iron-rich minerals, causing rust (e.g., reddish-brown iron oxide in rocks).
Carbonation: Carbon dioxide dissolves in rainwater, forming weak carbonic acid that dissolves limestone (e.g., cave formations).
Acid Rain: Sulfur and nitrogen pollutants create strong acids that accelerate rock decay.
Biological Activity: Lichens and plant roots release organic acids that dissolve minerals.

Examples of Chemical Weathering

● Karst Landscapes (e.g., Carlsbad Caverns): Limestone dissolves, forming caves and sinkholes.

● Tarnished Copper Statues (e.g., Statue of Liberty): Oxidation turns copper green.

● Laterite Soils (Tropical Regions): Heavy rainfall leaches minerals, leaving iron-rich soil.

Chemical weathering plays a crucial role in soil formation, nutrient cycling, and shaping Earth’s surface. It also contributes to climate regulation by absorbing CO₂ through carbonation.

Fun Fact: Acid rain can dissolve a marble statue 100 times faster than normal rain! This is why many ancient monuments and headstones develop a worn, eroded appearance over time as their minerals chemically react with acidic moisture in the air.

What is the main difference between chemical and mechanical weathering?

Chemical weathering only occurs in desertsChemical weathering changes mineral compositionMechanical weathering requires waterMechanical weathering happens faster

Which process turns feldspar into clay?

OxidationHydrolysisCarbonationAcid rain

What causes rust-colored stains on rocks?

HydrolysisOxidationCarbonationBiological activity

How does carbonation weather limestone?

Freezing water expands in cracksCarbonic acid dissolves the rockOxygen reacts with ironPlant roots pry rocks apart

Where would you expect intense chemical weathering?

Polar ice capsTropical rainforestsSandy desertsMountain peaks

What human activity accelerates chemical weathering?

Planting treesBurning fossil fuels (acid rain)Building damsMining coal

Which landmark shows oxidation effects?

Grand CanyonStatue of LibertyMount EverestGreat Barrier Reef