Chemical weathering is the chemical transformation of minerals in the saprolite and soil from one form to another under the action of solutions that (typically) contain water and dissolved acids. The reactions between the solution and the minerals results in (1) dissolved products, (2) precipitates, and (3) insitu transformation of the (primary) minerals into secondary minerals. The dissolved products typically exit the catchment as part of the dissolved load of the rivers and streams, though they can be precipitated elsewhere in the soil profile and/or the broader catchment if the chemical environment changes (e.g. pH changes). The precipitates may end up coating the existing matrix particles (and thereby inhibiting further reactions) or they may cement the particles together. The rate of the reaction is a function of the surface area of the soil matrix, and the concentration in the solution near the matrix. Precipitation of weathering on matrix particles will reduce the rate of weathering. Finally, the matrix is heterogeneous with a range of minerals, different exposures of these minerals to the solution, and the different minerals will react at different rates.