Thu September 08, 2011 By: Surya Prakash

Why is KCl more soluble in water than LiCl?Explain differences in their polarity and covalent character

Expert Reply
Fri September 09, 2011

Polarizing power for cations is very much a case of increasing with increased ion charge/ionic radius. So, the smaller the ionic radius or the bigger the positive charge, the greater the polarizing power of the cation. For Group ions, polarizing power will decrease down the group with increasing ionic radius and constant charge. Therefore in polarizing power Li+ > Na+ >K+ for Group 1 Alkali Metals etc. The greater the polarization produced more is the concentration of the electrons between the two atoms thereby decreasing the ionic character or increasing the covalent character. The covalent character of any compound in general depends upon the size of the cations. Smaller the cation, greater is its polarizing power and hence larger is the covalent character. The covalent character decreases as size of cation increases LiCl > NaCl > KCl > RbCl > CsCl. Thus LiCl is more covalent than KCl and hence KCl is more soluble in water because of decreased covalent character.


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