Students will be able to…

Define Weathering, and Chemical Weathering and discuss its effects on the earth.

List and describe 2 types of chemical weathering:

Warm-up Complete physical weathering lab Notes and discussion chemical weathering Worksheet weathering 1-4 and missing letter

vocab. chap. 14 Organize notebook to turn in from last unit

CHEMICAL WEATHERING CHEMICAL WEATHERING – is the

process of breaking down rock by changing a rock’s chemical composition.

Chemical Weathering

3 main types of chemical weathering:

1. Oxygen – causes rusting, (oxidation) – is the chemical process in which oxygen combines with another substance. Fe + O2 = FeO2 (rust)

2. Action of Acids – carbon dioxide combines with water and forms carbonic acid a weak acid that slowly breaks down rock (acid rain)

Acid especially breaks down calcite minerals in the rocks (Limestone and Marble.)

Acid especially breaks down calcite minerals in the rocks (Limestone and Marble.)

In an area composed of limestone rocks water and carbonic acid can dissolve out large underground caverns or caves.

The weathering process in caves also makes some unique features.

Stalactite – an icicle-like structure hanging from cave ceiling.

Stalagmite – an icicle-like structure built up from cave floor. (If joined it’s called a pillar)

A cave explorer is called a spelunker.

3. The most powerful and important chemical

weathering agent is water (hydration)

a. Can dissolve minerals out of rock

b. Water can combine chemically with certain

rock minerals in a process called hydration –

water reacts(chemically) to the minerals in

rock

Granite Contains:

Orthoclase feldspar + water = Kaolin (clay)

All that’s left behind is the mineral quartz.