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Phase transitions and hygroscopic growth of Mg(ClO4)2, NaClO4, and NaClO4·H2O: implications for the stability of aqueous water in hyperarid environments on Mars and on Earth Xiaohong Jia, Wenjun Gu, Yongjie Li, Peng Cheng, Yujing Tang, Liya Guo, Xinming Wang, and Mingjin Tang ACS Earth Space Chem., Just Accepted Manuscript • DOI: 10.1021/ acsearthspacechem.7b00143 • Publication Date (Web): 11 Jan 2018 Downloaded from http://pubs.acs.org on January 13, 2018
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ACS Earth and Space Chemistry
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Phase transitions and hygroscopic growth of Mg(ClO4)2, NaClO4, and NaClO4·H2O:
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implications for the stability of aqueous water in hyperarid environments on Mars
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and on Earth
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Xiaohong Jia,1,5,+ Wenjun Gu,1,5,+ Yong Jie Li,2 Peng Cheng,3,* Yujing Tang,4 Liya Guo,1,5
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Xinming Wang,1,6 Mingjin Tang1,*
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1 State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of
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Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry,
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Chinese Academy of Sciences, Guangzhou 510640, China
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2 Department of Civil and Environmental Engineering, Faculty of Science and Technology,
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University of Macau, Avenida da Universidade, Taipa, Macau, China
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3 Institute of Mass Spectrometer and Atmospheric Environment, Jinan University, Guangzhou
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510 632, China
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4 School of Environmental Studies, China University of Geosciences, Wuhan 430074, China
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5 University of Chinese Academy of Sciences, Beijing 100049, China
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6 Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment,
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Chinese Academy of Sciences, Xiamen 361021, China
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+ The two authors contributed equivalently to this work.
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*
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(
[email protected])
Correspondence:
Peng
Cheng
(
[email protected])
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1 ACS Paragon Plus Environment
and
Mingjin
Tang
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Abstract
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In general pure liquid water is not thermodynamically stable on Mars due to the
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extremely cold and dry environment. The presence in the soil of perchlorates, which could lower
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the freezing point of water and form aqueous solutions by taking up water vapor even under
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subsaturated conditions, has been proposed to explain the possible existence of liquid water on
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Mars and in some hyperarid environments on Earth. In this work, the phase transitions and
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hygroscopic growth of Mg(ClO4)2, NaClO4, and NaClO4·H2O were investigated between 278
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and 303 K. In this temperature range, we found that anhydrous Mg(ClO4)2 was completely
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converted to Mg(ClO4)2·6H2O at RH as low as
