Vapour-Liquid Equilibrium P1 Flashcards
What is the Phase Rule in words?
In a multiphase system at equilibrium, to know thermodynamic properties you need to know several intensive properties. The no. of variables we need to know to specify the state is the no. of degrees of freedom
What is the Phase Rule equation?
Nf=Nc+2-Np
Define an intensive property
The value for the whole system is the same as for any subdivision.
Define an extensive property
The value for the whole system is the sum of the values of individual parts
What is a 2 phase binary mixture
2 phases, mixed together at the same pressure or temperature
Give an example of a 2 phase binary mixture
Vapour Liquid Equilibrium
What is the degree of freedom in a 2 phase binary mixture
2, but 1 in experiments as T or P is usually fixed
What is the More Volatile Component (MVC)
The component with the lower boiling point
Material Balance equations
z=qx+(1-q)y
Equation for q
q=(y-z)/(y-x)
List the 5 states in the expansion of a mixture in variable volume
sub-cooled liquid, bubble point, two-phase region, dew point, super-heated vapour
What is a horizontal tie line
A construction which connects the compositions of coexisting phases
What are z, x and y in notation
z= mole fraction og MVC in the feed to a steady flow process, or in the whole system for a closed batch process
x=mole fraction of MVC in liquid phase
y=mole fraction of MVC in vapour phase
How do you calculate the composition of a L+V phase
Draw a horizontal tie line, get values for x, y and z, then use them to fine q, which is the liquid fraction
