Water, in either liquid or solid form, is often a key agent of mechanical weathering. For instance, liquid water can seep into cracks and crevices in rock. If temperatures drop low enough, the water will freeze. When water freezes, it expands.

Water plays a very important role in chemical weathering in three different ways. First, it combines with carbon dioxide in the soil to form a weak acid called carbonic acid. Finally, the water can break up minerals through hydrolysis . The most common group of minerals, the silicates, is decomposed by this process.

Water, air, and chemicals released by organisms cause chemical weathering of rocks when they dissolve the minerals in a rock. They can also cause chemical weathering by reacting chemically with the minerals in the rock to form new substances. Mechanical weathering breaks rocks down into smaller pieces.

The role of water in the chemical weathering of rock is that It aids in changing the chemical composition of rock. The CaHCO3 is aqueous meaning it dissolves in the water and is washed away with water leaving the rock brittle. Another example is rocks with iron minerals.

Water can completely dissolve some minerals, such as salt. Follow this link to check out this animation of how water dissolves salt. Hydrolysis is the name of the chemical reaction between a chemical compound and water. When this reaction takes place, water dissolves ions from the mineral and carries them away.

Physical Weathering in Nature. When water in a river or stream moves quickly, it can lift up rocks from the bottom of that body of water. As ice forms in the cracks of a street, the water expands and pushes against the surrounding rock, making the cracks wider, eventually breaking apart the rock.

Chemical weathering is caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. These reactions occur particularly when the water is slightly acidic.

Positive Impacts • The weathering of rocks helps to form the basic component of soil. Soil is very essential for Human Activities . It enables farming for food crops. Humans cause increases in acid rain and pollution, which increase the amount of weathering agents in the air and water, and then on land.

Landslides and soil erosion are two major effects of weathering.