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首页> 外文期刊>ACS Omega >Stability of the Liquid Water Phase on Mars: A Thermodynamic Analysis Considering Martian Atmospheric Conditions and Perchlorate Brine Solutions
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Stability of the Liquid Water Phase on Mars: A Thermodynamic Analysis Considering Martian Atmospheric Conditions and Perchlorate Brine Solutions

机译：MARS液相水相的稳定性：考虑Martian大气条件和高氯酸盐盐水溶液的热力学分析

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The stability of the liquid water phase on Mars has been examined on the basis of fundamental thermodynamic principles. The analysis considers the atmospheric pressure and temperature conditions prevalent on Mars. Because of the very low atmospheric pressure on Mars, water cannot exist in the liquid form. However, salt dissolution can reduce the freezing point and elevate the boiling point of aqueous solutions. This is interesting in the light of the discovery of perchlorate, sulphate, sodium, potassium, and calcium ions over the Martian surface. The effect of different perchlorate salts on the freezing and boiling points of water while considering their saturation solubility under varying ionic conditions is key to this analysis. It is shown that under an average atmospheric pressure of 600 Pa, the saturated solution of sodium perchlorate (NaClO_(4)) is stable in the liquid phase in the temperature range between 240 and 275 K. The triple point of water under this condition is shifted to 269 K with a saturation solubility of 14.4 mass % of the salt. However, a saturated solution of magnesium perchlorate (Mg(ClO_(4))_(2)) renders this temperature range wider from 198 to 296 K, with the triple point being located at 269 K (salt saturation at 13.5 mass % salt). In case the water is contaminated with a mixture of these salts, an increased stability is predicted for liquid water down to 180 K and up to at least 298 K. This is caused by the increased ionic strength that enhances the freezing point depression and boiling point elevation of the solution. Thus, in the extreme and uneventful conditions of saturation by mixtures of salts, liquid water can be stable on Mars between 180 K and at least up to 298 K. Below this temperature, water exists as a glacier and above, as steam only.
机译：基于基本热力学原理，研究了火星上液态水相的稳定性。分析考虑了火星上普遍的大气压和温度条件。由于火星上的大气压非常低，水不能以液体形式存在。然而，盐溶解可以减少冷冻点并提高水溶液的沸点。这鉴于在火星表面上发现高氯酸盐，硫酸盐，钠，钾和钙离子的光临。在根据不同离子条件下考虑其饱和溶解度的同时，不同高氯酸盐对水的冷冻和沸点的影响是该分析的关键。结果表明，在600Pa的平均气压下，在240和275k的温度范围内的液相中饱和溶液（NaClO_（4））稳定。在这种情况下的三点水是将饱和溶解度的饱和溶解度为14.4质量％的盐转移到269 k。然而，高氯酸镁（Mg（ClO_（4））_（2））的饱和溶液将该温度范围从198升至296k，三针位于269k（13.5质量％盐时的盐饱和） 。如果水被这些盐的混合物污染，预测液体水降至180k的稳定性增加，并且最高可达298k。这是由增加凝固点抑制和沸点的离子强度增加引起的溶液的升高。因此，在通过盐的混合物的极端和平坦的饱和条件下，液态水可以在180k和至少298k之间的火星上稳定。低于该温度，水作为冰川和上述冰川，作为蒸汽。

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