Definition of Chemical Weathering
- Planet Dictionary and Kids Geo explain that chemical weathering is a process of decay or decomposition. During chemical weathering, chemical reactions break down the minerals in a rock. As a result, the rock breaks into smaller and smaller pieces.
- Chemical bonds hold together every atom and molecule in any rock, and every atom and molecule has an electrical charge (positive or negative). The same holds true for outside agents like water. When rocks come in contact with outside agents, the differences in the electrical charges causes some of the bonds in the rock to break. As a result, the rock can't stay together and falls apart into smaller pieces. If enough bonds are broken, the entire rock may disintegrate into sand.
- Chemical weathering can happen on just about any rock, according to Kids Geo. However, smaller rocks have a greater surface area. This means that they are more susceptible to chemical weathering because more of the rock's surface is exposed to outside agents. However, size alone is not enough to determine how much chemical weathering will take place because some rocks have stronger bonds than others. The stronger the bonds in the rock, the less chemical weathering destroys the rock.
- Kids Geo points out that water-based agents facilitate chemical weathering because of the fact that water is necessary for many of the decaying chemical reactions to occur within the rock.
- People sometimes confuse chemical and physical (mechanical) weathering because both types of weathering result in the breaking down of a rock into smaller parts. However, according to the American Geological Institute, in physical weathering, the rocks break down without a chemical change occurring. For example, when rust forms on iron, a chemical change is evident in the presence of iron oxide--this thus is chemical weathering. By contrast, ice in a crack in a rock may force the rock into pieces as the ice expands. Since you still have only rock and water, no chemical change has happened, and physical weathering has occurred.