Related Experiment Video
Updated: Nov 3, 2025

Measuring the Densities of Aqueous Glasses at Cryogenic Temperatures
Published on: June 28, 2017
Predicting Deliquescence Relative Humidities of Crystals and Crystal Mixtures
Heiner Veith1, Christian Luebbert1, Gabriele Sadowski1
1Laboratory of Thermodynamics, Department of Chemical and Biochemical Engineering, TU Dortmund University, Emil-Figge-Str. 70, D-44227 Dortmund, Germany.
Abstract:
The presence of water in the form of relative humidity (RH) may lead to deliquescence of crystalline components above a certain RH, the deliquescence RH (DRH). Knowing the DRH values is essential, e.g., for the agrochemical industry, food industry, and pharmaceutical industry to identify stability windows for their crystalline products. This work applies the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) to purely predict the DRH of single components (organic acids, sugars, artificial sweeteners, and amides) and multicomponent crystal mixtures thereof only based on aqueous solubility data of the pure components. The predicted DRH values very well agree with the experimental ones. In addition, the temperature influence on the DRH value could be successfully predicted with PC-SAFT. The DRH prediction also differentiates between formation of hydrates and anhydrates. PC-SAFT-predicted phase diagrams of hydrate-forming components illustrate the influence of additional components on the hydrate formation as a function of RH. The DRH prediction via PC-SAFT allows for the determining of the stability of crystals and crystal mixtures without the need for time-consuming experiments.
Related Concept Videos
Recrystallization: Solid–Solution Equilibria
Precipitation Processes
Volatilization
Precipitation of Ions
The equation that describes the equilibrium between solid calcium carbonate and its solvated ions is:
Crystal Growth: Principles of Crystallization
Initiating crystallization involves manipulating the concentration of the solute and the temperature of the solution. Since crystal growth occurs when the ratio of concentration and solubility of the solute in the solvent...
Washing, Drying, and Ignition of Precipitates

