1. Dissolution: This is the process where minerals in rocks are dissolved by acidic water. A common example is the dissolving of limestone by rainwater containing dissolved carbon dioxide, forming caves and sinkholes.

2. Hydrolysis: This process involves the reaction of water with minerals in rocks, breaking down the mineral structure. This often occurs with silicate minerals, which are common in many rocks.

3. Oxidation: This is the reaction of minerals with oxygen, often in the presence of water. A classic example is the rusting of iron, where iron oxide forms, weakening the rock.

4. Biological Weathering: While not always categorized as chemical weathering, this type of weathering involves the breakdown of rocks by organisms. For example, lichens produce acids that can dissolve rock, and plant roots can exert pressure that cracks rocks.

These are just a few examples of chemical weathering. There are many other processes that can contribute to the breakdown of rocks over time.