METASTABILITY IN DIFFUSING-REACTING SYSTEMS

Nucleation in non-homogeneous diffusing-reacting systems occurs under a changing supersaturation. Under these conditions, the rate of creati on of supersaturation determines the value of the supersaturation thre shold at the nucleation time, i.e., the actual maximum metastability l evel. Measurements of metastable zone-widths and their dependence on t he supersaturation rate are here reported for different carbonates and sulphates. By analogy with nucleation behaviour by continuous cooling of saturated solutions, a semiempirical relation appears to govern th is dependence. Finally, this relation is checked for solutions doped w ith additives and metastability measurements in U-tube gel systems are proposed to compare inhibitor effectiveness.