is fed to an equilibrium stage. The separation requires
addition of a material separating agent S. The output
from the equilibrium stage is two phases. Phase I con-
tains A, B, C, and most of the added S. Phase II con-
tains B, C, D, E, and some S. Write down all material
balance equations using mole fractions and total
molar flows as variables, all phase equilibrium rela-
tionships (in the form x₁ =f(x), and equations
showing that mole fractions must sum to 1. List all