Controlling factors on the reaction rate

The reaction rate mainly depends on the concentration of reactants and products. According to the collision theory, frequent collisions and rapid conversions occur at high concentrations. Yet not all collisions cause conversions, a certain position of the molecules to each other as well as a certain threshold energy are required. Besides the concentration, pH, light, temperature, organics, presence of catalysts, and surface-active trace substances can have a significant influence on reaction rates. 

The empirical Arrhenius equation describes the dependency of the reaction rate on the temperature 

Reaction or process range of typical Ea-values [kcal/moll 

V = mass of solution (kg water) m, lk = initial mineral mass (mol) mk = mass of the mineral (mol) at a time t (mk/mok)n is a factor, which takes into account the change in A0 /V during the dissolution. For a steady dissolution from surfaces and cubes n is 2/3. Frequently not all parameters are available, so that simple approaches are useful like  

83 kK is an empiric constant and SR is the saturation rate (ion activity product / solubility product). Frequently the exponent o equals 1. The advantage of this simple equation is that it is valid both for supersaturation and undersaturation. With saturation RK becomes zero. RK can also be expressed by the saturation index [log (SR)] (Appelo et al. 1984)  

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