The effect of chemical complexation on the precipitation of metal cations in a strong acid medium by the addition of anions of a weak acid is investigated. Chemical kinetic models of precipitation based on second order consecutive reactions are used to represent the kinetics of complexation and precipitation. These models are compared with data from two stage precipitation experiments using the following chemical systems: 2La(NO3)3 + 3H2 = 3H2C2O4 + 6HNO3 and Ca(OH)2 + H2SO4 = CaSO4 + 2H2O. The particle size distribution and particle morphology are correlated with the condition which determines the crystallization kinetics. A novel technique based on Fourier series descriptors of the crystal shape is applied to characterize the shapes of the crystals formed in this work.
