1. Dissolution:

* How it occurs: This is the process of minerals dissolving in water. Water molecules have a slightly positive charge on one side and a slightly negative charge on the other, making them polar. This polarity allows water to break apart the bonds holding minerals together, dissolving them.

* Examples:

* Dissolving limestone: Rainwater slightly acidic due to dissolved carbon dioxide forms carbonic acid. This acid reacts with limestone (calcium carbonate) to dissolve it, creating caves, sinkholes, and karst landscapes.

* Dissolving halite (rock salt): Salt is readily soluble in water, so it dissolves easily, especially in areas with high rainfall or near bodies of water.

2. Oxidation:

* How it occurs: This is the process of a substance combining with oxygen, often in the presence of water. Iron, a common component in many rocks, is particularly susceptible to oxidation.

* Examples:

* Rusting: When iron in rocks is exposed to oxygen and water, it forms iron oxide (rust). Rust is weaker than the original iron, causing the rock to crumble and break down.

* Oxidation of sulfides: Minerals like pyrite (iron sulfide) can react with oxygen and water to form sulfuric acid. This acid can further react with other minerals, leading to their breakdown.

Key points to remember:

* Chemical weathering involves changes in the chemical composition of rocks.

* Water plays a crucial role in most chemical weathering processes.

* Chemical weathering can be accelerated by factors like temperature, acidity, and the presence of oxygen.