Unit 1 Lesson 2 Chemical Weathering Copyright © Houghton Mifflin Harcourt Publishing Company

Reaction What causes chemical weathering? Unit 1 Lesson 2 Weathering Reaction What causes chemical weathering? Chemical weathering is the breakdown of rocks by chemical reactions. Chemical weathering changes both the composition and appearance of rocks. Agents of chemical weathering include oxygen in the air and acids. Copyright © Houghton Mifflin Harcourt Publishing Company 2

What causes chemical weathering? Unit 1 Lesson 2 Weathering What causes chemical weathering? Oxidation is the process by which chemicals in rock combine with oxygen in the air or in water. Rock surfaces sometimes change color, indicating that a chemical reaction may have occurred. Copyright © Houghton Mifflin Harcourt Publishing Company 3

What causes chemical weathering? Unit 1 Lesson 2 Weathering What causes chemical weathering? Acids can cause chemical weathering by breaking down minerals faster than water alone. Acids in the atmosphere are created when chemicals combine with water in the air. Acid precipitation occurs when strong acids fall to Earth as rain, sleet, or snow. Copyright © Houghton Mifflin Harcourt Publishing Company 4

What causes chemical weathering? Unit 1 Lesson 2 Weathering What causes chemical weathering? Acids in groundwater can cause rock to dissolve. A small crack in the rock can result in the formation of extensive cave systems carved out over time. Rock material dissolved in groundwater can be carried and deposited in new locations over time. Copyright © Houghton Mifflin Harcourt Publishing Company 5

What causes chemical weathering? Unit 1 Lesson 2 Weathering What causes chemical weathering? Acids produced by living things can cause chemical weathering. Chemical reactions occur as these acids move through tiny spaces in rock material. As the acids seep deeper, cracks form. Eventually, the rock can break apart. Copyright © Houghton Mifflin Harcourt Publishing Company 6