Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (02): 154-157.doi: 10.3866/PKU.WHXB20030213

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Raman Spectroscopic Study of Effect of CaCl2 and MgCl2 on Structure of Water

Li Rui-Hua;Jiang Zhan-Peng;Shi Shao-Qi;Yang Hong-Wei   

  1. Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084
  • Received:2002-04-16 Revised:2002-06-26 Published:2003-02-15
  • Contact: Jiang Zhan-Peng

Abstract: Raman spectra of aqueous solutions of CaCl2 and MgCl2 in the OH stretching region (2 500 to 4 000 cm-1) with various concentrations below 1.0 mol•L-1 were measured. Computer deconvolutions of the Raman spectra allow the percent of tetrahedral hydrogen bonded structure of water to be determined. It is shown that CaCl2 and MgCl2 break tetrahedral hydrogen bonded structure of water and the breaking effect of Ca2+ is stronger than that of Mg2+. By comparison with results of 17O NMR, it is deduced that CaCl2 and MgCl2 promote structure of water as a whole by forming hydrogen bonding among water molecules with fewer hydrogen bonding even though they break tetrahedral hydrogen bonded structure of water.

Key words: Water, Raman spectrum, CaCl2, MgCl2, Hydrogen bonding