This article was originally published as: de Burg, K. (2011). Raoult's Law: a Reinterpretation for concentrated strong 1:1 electrolyte solutions. Australian Journal of Education in Chemistry, 71, 15-18.
Chemistry textbooks typically mention that Raoult’s Law is strictly applicable only for ideal solutions which usually also means very dilute solutions. Non-ideal behaviour for electrolytes is normally accounted for using activity coefficient data. It has recently been shown that for strong 1:1 electrolytes departure from ideal behaviour is best interpreted through the Arrhenius model of partial dissociation and the Armstrong model of ionic hydration. The new model of strong electrolytes, first proposed by Raja Heyrovska, distinguishes between free and bound molecules of water at the surface and bulk of a solution and involves the calculation of fractional dissociation values (a) hydration numbers (ns, nb)concentrated strong 1:1 electrolytes if it is reinterpreted in terms of the Heyrovska model of an electrolyte solution. Examples are discussed here for the alkali chlorides with some important implications for the teaching of thermodynamics.
de Berg, Kevin, "Raoult's Law: A Reinterpretation for Concentrated Strong 1:1 Electrolyte Solutions" (2011). Science and Mathematics Papers and Journal Articles. 31.