An X-ray diffraction study on concentrated aqueous calcium nitrate solutions at subzero temperatures

✍ Scribed by Pavel Smirnov; Motoyuki Yamagami; Hisanobu Wakita; Toshio Yamaguchi

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 759 KB
• Volume: 73-74
• Category: Article
• ISSN: 0167-7322
• DOI: 10.1016/s0167-7322(97)00075-5

✦ Synopsis

X-ray scattering measurements on aqueous solutions of Ca(NO& * R H20 with R = 6 and 12 have been performed over a temperature range of 258 -298 K. The analysis of the X-ray data gave the coordination number of Ca2' nearly seven with a Ca2'-0 distance = 247 pm. It has been found that with decreasing temperature the hydration shells of Ca" and NOs' are significantly perturbed in the saturated solution (R= 6) accompanied by evolving of hydrogen bonded network in the water structure. Contact ion-pairs between Ca*' and NO< are present in both solutions, as also evidenced by Raman spectroscopy, the nitrate ion coordinating to Ca" in a monodentate fashion with a Ca" -N(NOa) distance 300 -3 10 pm.