Chemical Weathering

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Physical Change Noun

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[fiz-i-kuhl cheynj]

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Physical Change

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A change where the form of a substance is altered, but its chemical composition remains the same.

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Example: This diagram shows that when ice cubes melt into liquid water, the substance is still water, just in a different state, illustrating a physical change.

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Chemical Change Noun

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[kem-i-kuhl cheynj]

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Chemical Change

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A change that results in the formation of a new substance with a different chemical composition and properties.

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Example: This image shows four indicators of a chemical change, such as the color change when a padlock rusts, which is a form of chemical weathering.

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Weathering Noun

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[weth-er-ing]

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Weathering

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The physical and chemical breakdown of rocks and minerals at or near the Earth's surface.

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Example: This image illustrates four types of chemical weathering, including reactions with water to form caves and with oxygen to create rust on rocks.

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Chemical Weathering Noun

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[kem-i-kuhl weth-er-ing]

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Chemical Weathering

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The decomposition of rocks through chemical reactions that change their mineral composition into new materials.

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Example: This image illustrates four types of chemical weathering: water forming caves, oxygen rusting rocks, acid dissolving surfaces, and organisms breaking down rock.

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Mechanical Weathering Noun

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[muh-kan-i-kuhl weth-er-ing]

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Mechanical Weathering

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The physical breakdown of rocks into smaller pieces without altering their chemical composition.

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Example: Water seeps into a crack in a rock, freezes and expands, and then breaks the rock apart, demonstrating a type of mechanical weathering.

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Hydrolysis Noun

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[hahy-drol-uh-sis]

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Hydrolysis

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A chemical weathering process involving the reaction between a chemical compound in a mineral and water.

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Example: A water molecule (H2O) is used to break down a larger molecule (A-B) into two smaller pieces (A-H and B-OH).

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Hydration Noun

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[hahy-drey-shuhn]

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Hydration

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A chemical weathering process where minerals absorb water into their structure, causing them to expand and change.

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Example: This image shows the mineral anhydrite absorbing water and transforming into the mineral gypsum, an example of chemical weathering through hydration.

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Carbonic Acid Noun

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[kahr-bon-ik as-id]

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Carbonic Acid

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A weak acid formed when carbon dioxide dissolves in water, which is a key agent in chemical weathering.

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Example: When carbon dioxide (CO₂) from the air dissolves in water (H₂O), they combine to form a weak acid called carbonic acid (H₂CO₃).

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Carbonation Noun

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[kahr-buh-ney-shuhn]

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Carbonation

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The process of chemical weathering where carbonic acid reacts with and dissolves minerals in rock, like calcite.

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Example: This image shows four types of chemical weathering; the top-left panel illustrates a cave formed by carbonation, where acidic water dissolves rock.

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Oxidation Noun

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[ok-si-dey-shuhn]

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Oxidation

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A chemical weathering process where elements in minerals, particularly iron, react with oxygen from the air or water.

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Example: This image shows that oxidation is a chemical process where an atom loses an electron, using a browning apple as a real-world example.