Review of Ammonium Chloride–Water Solution Properties

Ammonium chloride is commonly used as a buffer solution to control pH levels in a wide variety of chemical and medical applications and is also used as a fertilizer because it acts as a sufficient source of nitrogen for the soil. More recently it is used to create an experimental benchmark, useful to model/simulate metal solidification. In electronics and metallurgy it is also used for cleaning, to prevent the formation of oxides during welding or smelting of metals. In the literature different values are available for the thermo-physical parameters and in the current paper an overview of measured or calculated values of the most important properties is presented. For an ammonium chloride–water solution different phase diagrams are accessible, and the calculation of the liquidus and solidus line is completed. A comparison of calculated heat capacity values for ammonium chloride is made with the literature values. Measured data for the ammonium chloride density are available in the literature, and the values for different temperatures and concentrations are presented here. Thermal conductivity values are gathered in the present work. The viscosity can be estimated in between 283 and 333 K and for mass fraction up to 0.324 kg·kg–1, with a model for the calculation of the aqueous solutions viscosity, based on the viscosity of solute and water. The variation curve of diffusivity values with the concentration, exists only for 293 and 298 K. For this reason an approximation with NH3 diffusivity values, which are measured for different temperatures and concentrations, can be recommended. Additional analysis of two experimental measurements, performed in order to estimate the ammonium chloride diffusivity in water and further extract the Gibbs–Thomson coefficient, is done.