## Section 1.2.2.2: Solution Options

It is clear that as we have 6 equations and 8 variables, only 6
of the variables may be unknown for us to be able to solve the equations.
This means that values must be given for two of them.

(We may either think of this as reducing the number of unknowns by
replacing two of them by numerical values, or as augmenting
the set of equations by adding another two which have the simple form
of, e.g.:

*P* = 1.013

*T* = 293

Typical options for the specifications are as follows:

*P* and one *x*_{i} value: bubble point temperature calculation
*T* and one *x*)*i*: bubble point pressure calculation
*T* *or * *P* and one *y*_{i} value: dew point temperature or pressure
calculation
*T* and *P*: `isothermal' phase composition calculation.

In each case all the remaining variables are determined. The
solution methods required in each of the above cases are interestingly
different. These will be explored in examples.

Return to Revision Index

Return to Section 1.2.2: Binary Vapour Liquid Phase Equilibrium