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Interionic Attractions

This theory was discovered due to Arrhenius's theory having deficiencies. Arrhenius's theory states that ions exist in a solid substance and dissociated from each other once the solid dissolves. Arhennius's theory did not take into account the fact that strong electrolytes are not as great as he originally thought and the values of the van't Hoff factor i relied on the concentration of the solution. The theory of electrolyte solution was brought about by Peter Debye and Erich Huckel in 1923.

Interionic Attractions are when an ion is surrounded by an ionic atmosphere which has a net charge opposite for its own. For example an anion would be completely surrounded by ions mostly composed of cations and a cation would mostly be surrounded by ions of anions. The ionic atmosphere decreases the mobility of each ion by exerting a drag on it, which in turn also decreases the magnitude of colligative properties. The ionic atmosphere cannot created nor destroyed.

In solutions with weak electrolytes the number of ions is not large, therefore the effect of the interionic attraction is small. In a concentrated solution of strong electrolytes the ion count is large, and therefore the interionic attraction will be apparent. The reason behind the differences in the interionic attraction is that in concentrated solutions ions are closer together due to the large ion count, while in less concentrated solutions they are further apart.

References

  1. Petrucci, Harwood, Herring, Madura. General Chemistry: Principles & Modern Applications, Ninth Ed. Upper Saddle River, NJ: Pearson Education, Inc., 2007.
  2. Falkenhagen, H. "The Principal Ideas in the Interionic Attraction Theory of Strong Electrolytes." Reviews of Modern Physics (1931): 1-15.
  3. Goss, Dixie J. Study Guide: General Chemistry. Upper Saddle River, NJ: Pearson Prentice Hall, 2007.
  4. Negi, A.S. and A.C Anand. A Textbook of Physical Chemistry. New Delhi: New Age Publishers, 1986.

Contributors

  • Cindy Ramirez (UCD)