The thermodynamic equilibrium of solid–liquid and solutions of the mixed system of sodium and hydrogen fluorides were investigated at various temperatures. The chemical speciation of the $\text{N}\text{a}\text{F}-\text{H}\text{F}$ in aqueous solutions was described; which the considered equilibrium is dissociating into the species ${\text{N}\text{a}}^{+}(\text{a}\text{q})$, ${\text{H}}^{+}(\text{a}\text{q})$, $\text{H}\text{F}(\text{a}\text{q})$, ${\text{F}}^{-}(\text{a}\text{q})$, ${\text{H}{\text{F}}_2}^{-}(\text{a}\text{q})$ and ${{\text{H}}_2{\text{F}}_3}^{-}(\text{a}\text{q})$. The species molalities are strongly dependent on the concentration in the solution, therefore directly influence the thermodynamic properties. Neglecting this concentration dependence leads to erroneous osmotic coefficients for weak electrolyte solutions. Then, the water activity measurements of the mixed system $\left\{\left.y\text{H}\text{F}+\left(1-y\right)\text{N}\text{a}\text{F}\right\}\left(\text{a}\text{q}\right)\right.$ were performed at various temperatures from 298.15 K to 353.15 K using the hygrometric method. These measurements were made as a function of total molality ranging from dilution to saturation for different ionic-strength fractions y with respect to the support solute $\text{H}\text{F}$ with y = 0.20, 0.50, and 0.80. The mixed aqueous electrolytes were considered as a polyelectrolyte system ${{[\text{N}\text{a}}^{+}-\text{H}{\text{F}}^0-{\text{H}}^{+}-{\text{F}}^{-}-{\text{H}{\text{F}}_2}^{-}-\text{H}}_2{{\text{F}}_3}^{-}-{\text{H}}_2\text{O}]$. Based on the ion interaction model, the thermodynamic model was developed to describe the behavior of sodium and hydrogen fluorides in aqueous solutions at different temperatures. The species molalities of the $\text{H}\text{F}(\text{a}\text{q})$, ${\text{N}\text{a}}^{+}(\text{a}\text{q})$, ${\text{H}}^{+}(\text{a}\text{q})$, ${\text{F}}^{-}(\text{a}\text{q})$, ${\text{H}{\text{F}}_2}^{-}(\text{a}\text{q})$ and ${{\text{H}}_2{\text{F}}_3}^{-}(\text{a}\text{q})$ of the system were evaluated. The new ion interaction parameters ${\Phi }_{H^{+},{Na}^{+}}$ and ${\Psi }_{H^{+},{Na}^{+},F^{-}}$ were determined at various temperatures and used to calculate the species activity coefficients as a function of total molality for different ionic-strength fractions (y). The developed model exhibits a high consistency for the treatment of polyelectrolyte system. The results allow describing the behavior of the mixed NaF-HF in aqueous solutions. The solubility of the sodium fluoride in hydrofluoric acid aqueous solutions were also performed, and the formed solid phases were characterized by X-ray diffraction analysis. The obtained crystal forms were identified to $\text{N}\text{a}\text{F}$ (s) and $\text{N}\text{a}\text{H}{\text{F}}_2(\text{s})$ for y = 0.20 and y= (0.50 and 0.80) respectively.

在不同温度下研究了固液的热力学平衡以及氟化钠和氟化氢混合体系的溶液。的化学形态$\text{ñ}\text{一种}\text{F}--\text{H}\text{F}$描述了在水溶液中；所考虑的平衡正在分解为物种${\text{ñ}\text{一种}}^{+}（\text{一种}\text{q}）$， ${\text{H}}^{+}（\text{一种}\text{q}）$， $\text{H}\text{F}（\text{一种}\text{q}）$， ${\text{F}}^{--}（\text{一种}\text{q}）$， ${\text{H}{\text{F}}_2}^{--}（\text{一种}\text{q}）$ 和 ${{\text{H}}_2{\text{F}}_3}^{--}（\text{一种}\text{q}）$。物质的摩尔浓度强烈取决于溶液中的浓度，因此直接影响热力学性质。忽略这种浓度依赖性会导致弱电解质溶液的渗透系数错误。然后，测量混合系统的水分活度$\left\{\left.ÿ\text{H}\text{F}+\left(\mathrm{1个}--ÿ\right)\text{ñ}\text{一种}\text{F}\right\}\left(\text{一种}\text{q}\right)\right.$使用吸湿法在298.15 K至353.15 K的各种温度下进行测试。这些测量是相对于相对于载体溶质的不同离子强度分数y从稀释到饱和的总摩尔浓度的函数$\text{H}\text{F}$与ÿ  = 0.20，0.50，和0.80。混合的水性电解质被认为是聚电解质体系${{[\text{ñ}\text{一种}}^{+}--\text{H}{\text{F}}^0--{\text{H}}^{+}--{\text{F}}^{--}--{\text{H}{\text{F}}_2}^{--}--\text{H}}_2{{\text{F}}_3}^{--}--{\text{H}}_2\text{Ø}]$。基于离子相互作用模型，开发了热力学模型来描述水溶液中氟化钠和氟化氢在不同温度下的行为。物种的摩尔浓度$\text{H}\text{F}（\text{一种}\text{q}）$， ${\text{ñ}\text{一种}}^{+}（\text{一种}\text{q}）$， ${\text{H}}^{+}（\text{一种}\text{q}）$， ${\text{F}}^{--}（\text{一种}\text{q}）$， ${\text{H}{\text{F}}_2}^{--}（\text{一种}\text{q}）$ 和 ${{\text{H}}_2{\text{F}}_3}^{--}（\text{一种}\text{q}）$系统的评价。新的离子相互作用参数${\Phi }_{H^{+}，{ñ\mathrm{一种}}^{+}}$ 和 ${\Psi }_{H^{+}，{ñ\mathrm{一种}}^{+}，F^{--}}$在不同温度下测定的离子强度用于计算不同离子强度分数（y）的物种活度系数与总摩尔浓度的关系。所开发的模型对聚电解质体系的处理显示出高度的一致性。结果允许描述混合NaF-HF在水溶液中的行为。还进行了氟化钠在氢氟酸水溶液中的溶解性，并且通过X射线衍射分析表征了形成的固相。鉴定得到的晶形$\text{ñ}\text{一种}\text{F}$ （s）和 $\text{ñ}\text{一种}\text{H}{\text{F}}_2（\text{s}）$分别为y  = 0.20和y =（0.50和0.80）。