- Three Component Phase Diagram of the Water-Heptane-Propano...
Three Component Phase Diagram of the Water-Heptane-Propanol System. Illustrate your essay with specific examples.
A convenient way of illustrating the principles governing phase
changes within three component systems is to use a partially
miscible liquid system. In the past, the acid-chloroform-water
system has been employed as a practical example to investigate
ternary systems and the miscibility gap (Wright et al., 1891;
Brancker et al., 1940). However, since the status of chloroform has
been changed to a suspected carcinogen, these experiments have been
rendered unsuitable for teaching laboratories. A fitting
alternative is offered in the form of an alcohol-water-hydrocarbon
system (Washburn et al., 1931). Two undergraduate laboratory
experiments have been proposed in the past, based on the
water-n-heptane-n-propanol system and are similar to the previously
popular acid-chloroform-water experiments. However, whereas the
acid-chloroform-water experiments solely involve titration, these
experiments utilise other techniques. Udale and Wells (1995)
outline a method whereby a phase diagram can be constructed based
upon titration results but also describe how pairs of phases in
equilibrium can be quantified chromatographically. Karukstis et al.
(2000) describe a novel method whereby the phase diagram is
determined spectroscopically. The following suggested experimental
procedure describes both methods, aimed at teaching students the
principles of i) Gibbs phase law ii) phase diagrams iii) the three
component system and iv) the miscibility gap.
Gibbs phase law
The number of degrees of freedom, F, within a system is given
Thin layer Chromatography (Tlc) stage 2