Chemical Weathering Processes

Chemical Weathering Processes

• Oxidation is a process where oxygen bonds with other elements from rock-forming minerals, forming more stable substances, lower in energy, and with a larger volume and more distinct color.
• It commonly occurs to metals present in rocks, such as aluminum and iron, forming aluminum and iron oxides.
• Solution is the chemical process of dissolving rock-forming minerals in water, where mineral-forming ions are dissociated and carried away in water.
• Carbonation is the chemical weathering process that decomposes rocks through the aid of water and carbon dioxide, commonly occurring in rocks containing carbonates (CO) such as limestone.
• Hydrolysis is the process where water molecules alone react with rock-forming minerals, forming new products, and is different from hydration.

Factors Affecting Weathering Rate

• Rock structure affects the rate of weathering, with highly jointed/fractured rocks disintegrating faster than a solid mass of rock.
• Topography affects the rate of weathering, with physical weathering occurring more quickly in highly elevated areas with steep slopes.
• Time length of exposure to agents of weathering affects the rate of erosion, with parts of rock boulders that are exposed being more susceptible to weathering.

Differential Weathering and Erosion

• If a landscape contains a variety of rocks, some rocks are more susceptible to weathering and some are more resistant.
• Susceptible rocks undergo weathering faster and rock fragments are transported through the process of erosion.

Types of Mechanical Weathering

• Unloading is the type of mechanical weathering caused by the expansion of the upper portion of a block intrusive igneous rock.
• Thermal Expansion and Contraction is the type of mechanical weathering caused by high temperatures causing rock to expand and low temperatures causing rocks to contract, leading to cracking.

Physical and Chemical Change

• Physical change refers to changes limited to the physical attributes or appearance of an object without changing its chemical composition.
• Chemical change is the type of change that involves changes in its chemical composition and the formation of new products.