The solubility of NaF in water is important to a number of industries, but there is a limited review of the large amount of solubility data scattered throughout the literature. The present study collected all of the data on the NaF solubility in water that could be found in the peer-reviewed literature between the temperature 0 and 100.6 °C (the upper temperature being approximately the boiling point of a saturated solution). Fifty-five solubility data points were found, collected from 29 studies. There was a large amount of scatter among the data, both across and within most studies. After screening out suspect data, the solubility of NaF was found to be a linear function of temperature, with a change of solubility of 0.003 molal per °C. Averaging the data at 25 °C provides an estimated solubility of 0.987 molal at that temperature.

The solubility of sodium nitrite (NaNO2) in water is important to many industries, including those of heat pumps, oil extraction, and the management of alkaline nuclear waste. This study reviews solubility data for NaNO2 in water between the freezing point (−19 °C) and boiling point (128 °C) of a saturated solution. The temperature of the transition between the hemihydrate and anhydrous NaNO2 solid phases occurs at ca. −5 °C. There is excellent agreement between most studies above 0 °C, with the average solubility at 25 °C reported being 12.4 mol·kg–1 water. The electrical conductivity, viscosity, and density of saturated solutions were also reviewed, with mean values from several studies reported at 25 °C. The intrinsic volume of dissolved NaNO2 determined in this study (36.5 cm3·mol–1) is only 6% different from the value determined by extrapolating the density of molten salt to ambient temperatures. The flow in concentrated NaNO2 solutions behaves more like a molten salt than a soft colloidal behavior that more hydrated electrolytes resemble. Indeed, given that there is only ∼0.87 mol of water per mole of dissolved ion at 128 °C, the extremely high solubility of NaNO2 in water resembles a hydrated molten salt. A thermodynamic-based solubility model was developed.