Dissolving and melting phenomena of inorganic and organic crystals by addition of third or second components

Dissolution of potassium sulphate (K2SO4) crystals was decelerated or stopped since the trivalent chrome ions (Cr(III)) or the iron ions were added into a K2SO4 aqueous solution, but inhibition mechanism of crystal dissolving by additives is not discussed well. Moreover, the melting inhibition of organic compound crystals by addition of the second components is not reported. In this study, inorganic or organic compound crystals are dissolved in a solution added the third component or were melted in a melt added the second one, and the dissolving and melting inhibition phenomena of the inorganic and organic crystals with additives are discussed. The dissolving rates of K2SO4 crystals decreased with the increasing of the amount of Cr(III) added into an K2SO4 unsaturated solution. The melting rates of m-chloronitrobenzene (CNB) crystals were also decreased by addition of p-CNB. The dissolving rates of a K2SO4 mother crystal and the melting rates of a m-CNB mother crystal were scattered during experiments and the dissolving and the melting phenomena would be caused by adsorption and detachments of additives on and from crystal surfaces. •Dissolving rates of K2SO4 crystals decreased with increasing of the Cr(III) concentrations.•Dissolving rates of K2SO4 crystals were scattered with experimental durations.•The surfaces of a K2SO4 crystal dissolving in a solution with Cr(III) were covered with pyramids.•The melting rates of m-CNB crystals decreased with increasing of p-CNB compositions.•The corners of m-CNB crystal became rounded for case with p-CNB.