Hannay smith equation derivation

Our chemistry teacher taught us about Hannay smith equation for calculating the percent ionic character. He did not told how that equation was derived. I could not find any satisfactory result from google search either. But, I am curious to know how it was derived.


$$ \% \hspace{2mm} ionic \hspace{2mm} character=[16(\Delta E.N.)+3.5(\Delta E.N.)^2]\%$$


