Solubility Relations of the Ternary System Magnesium Nitrate—Nitric Acid—Water at 25°

Abstract

This further investigation1 was undertaken to confirm the existence of certain hydrates of magnesium nitrate; and to determine methods of preparation of these salts for calorimetric and vapor pressure measurements, which are being made in this Laboratory. Malquori2 investigated this system at 20°, but gives only fragmentary data up to 59.38% nitric acid. ExperimentalThe procedure was to make saturated solutions, and to analyze both the solution phase and the moist crystal phase for nitric acid and for zinc nitrate.Materials.-C. p. magnesium nitrate was prepared as previously described.1 C. p. nitric acid was prepared by distilling from a mixture of two volumes of sulfuric acid and one volume of nitric acid. The distillate was redistilled in a still having a long fractionating column and a controlled reflux. The fraction distilling over at 82°was collected. This brown acid which distilled over was decolorized by blowing dry air through it at 70 °. The acid thus purified analyzed 99-100% acid. A good grade of distilled water was used.Preparation of Saturated Solutions.-Mixtures" of the proper concentrations were made by weighing out requisite amounts of the three constituents. These were placed in two ounce tincture bottles having carefully ground glass stoppers. These bottles were then sealed with paraffin. The samples were then revolved in a water-bath at 25 =<= 0.020 for six hours. The concentration did not change after the third hour. The

A Pitzer Parametrization To Predict Solution Properties and Salt Solubility in the H–Na–K–Ca–Mg–NO3–H2O System at 298.15 K

“…Calculated (lines) and experimental (symbols) solubility of Mg­(NO 3 ) 2 –HNO 3 –H 2 O ternary system at 298.15 K. ○, ref ; −, nitromagnesite (Mg­(NO 3 ) 2 ·4H 2 O) solubility.…”

“…In Figure19, we plotted the osmotic coefficient as a function of ionic strength fraction of Ca(NO 3 ) 2 : y Ca(NO 3 ) 2 = 3m Ca(NO 3 ) 2 / (3m Ca(NO 3 ) 2 +3m Mg(NO 3 ) 2 ).Mg(NO 3 ) 2 −HNO 3 −H 2 O. Nitromagnesite (Mg(NO 3 ) 2 •4H 2 O) solubility is plotted as a function of HNO 3 molality in Figure20. Experimental data (symbols) are taken from Ewing and Klinger71 and evidence surprising behavior above 25 mol•kg −1 of HNO 3 , since two regions of salt-solution equilibrium can be identified. One extends at moderate concentrations of Mg(NO 3 ) 2 , that is, below 6 M, and the other extends at high Mg(NO 3 ) 2 concentrations, above 9 M. Because of this particular behavior, five parameters (ψ + + − λ HNO 3 /Mg +2 , μ HNO 3 /HNO 3 /Mg 2+ and η HNO 3 /H + /Mg 2+ ) are necessary to reproduce the experimental solubility data (Figure20), at least for the region of moderate Mg(NO 3 ) 2 concentrations.…”

Water Uptake and Release of Nitrate Salt Mixtures of Relevance to the Atacama Desert and Mars

“…14−16 On Earth, nitrates mixed with sodium chloride have been shown to inhibit the efflorescence of sodium chloride. 17 Previous studies of phase transitions of nitrates have mainly been performed at room temperature, 18,19 leaving gaps in our understanding of how nitrates and nitrate salt mixtures behave in terms of water uptake and release at Mars-relevant temperatures, specifically within the range of 210−293 K. Notably, magnesium nitrate (Mg(NO 3 ) 2 ) exhibits a high eutectic temperature of 240 K, 18 but its interaction with magnesium perchlorate (Mg(ClO 4 ) 2 ) may potentially lead to water uptake at even lower temperatures. In contrast to their nitrate and perchlorate counterparts, sulfate salts demonstrate lower hygroscopicity.…”

“…Previous studies of phase transitions of nitrates have mainly been performed at room temperature, , leaving gaps in our understanding of how nitrates and nitrate salt mixtures behave in terms of water uptake and release at Mars-relevant temperatures, specifically within the range of 210–293 K. Notably, magnesium nitrate (Mg(NO 3 ) 2 ) exhibits a high eutectic temperature of 240 K, but its interaction with magnesium perchlorate (Mg(ClO 4 ) 2 ) may potentially lead to water uptake at even lower temperatures. In contrast to their nitrate and perchlorate counterparts, sulfate salts demonstrate lower hygroscopicity. , However, sulfate salts are significantly more abundant than perchlorates and nitrates in both Martian soils and the Atacama Desert. , As observed in previous studies on salt mixtures, it has been found that less deliquescent salts can influence the water uptake behavior of more deliquescent salts .…”