Why Nonideal Behavior

What kinds of molecules would be expected to show the above four types of behavior We can offer the following 

Physical and Chemical Equilibrium for Chemical Engineers, Second Edition. Noel de Nevers. 2012 John Wiley Sons, Inc. Published 2012 by John Wiley Sons, Inc. 

Liquid-phase mol fraction of more volatile species, 

Chemical or quasi-chemical reactions between species lead to type III behavior. Solvation of molecules and ions is a weak quasi-chemical reaction, shown for sucrose and Na+ and Cl in Chapter 8. Strong quasichemical reactions like that between water and sulfuric acid lead to strong type III behavior. 

Some chemicals reversibly form dimers or trimers in both liquid and vapor phases, for example, carboxylic acids. This leads to type III behavior (see Chapter 13). 

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