Intro Lecture

Question 1

What is a chemical/biological plant?

Answer 1

A reactor surrounded by separators.

Question 2

What percentage do separation account for when it comes to capital and operating costs?

Answer 2

Represent 40-70% of capital and operating costs in a facility.

Question 3

What type of feed is used in mechanical operations?

Answer 3

Feed is heterogeneous (i.e.
consists of more than one phase)

Question 4

What type of feed is used in diffusional operations?

Answer 4

Feed is homogeneous (i.e. singlephase multicomponent mixture)

Question 5

What is the purpose of mechanical operations?

Answer 5

Purpose: separate the phases

Question 6

What is the purpose of diffusional operations?

Answer 6

Separate one or more
components via selective transfer
into a second phase

Question 7

What examples of mechanical operations?

Answer 7

e.g. filtration, clarification,
decantation, centrifugation

Question 8

What are examples of diffusional operations?

Answer 8

e.g. distillation, absorption,
extraction,

Question 9

What is interphase operation?

Answer 9

Mass transfer between two
immiscible phases in direct contact

Question 10

What is intraphase operation?

Answer 10

Mass transfer between two miscible
phases that are separated by a
permeable barrier called a
membrane

Question 11

Examples of Interphase Operation

Answer 11

e.g. gas permeation, dialysis and
reverse osmosis

Question 12

What do the molecules do during phase equilibria?

Answer 12

Molecules continually vaporize and
condensing

Question 13

Which parameters don’t change in equilibrium?

Answer 13

• Temperature
• Pressure
• Mole fractions of each phase

Question 14

Describe thermal equilibrium

Answer 14

vapor temperature = liquid temperature

Question 15

Describe mechanical equilibrium?

Answer 15

vapor pressure = liquid pressure

Question 16

What happens during phase equilibrium?

Answer 16

Rate at which A is vaporizing is equal
to rate at which A is condensing

Question 17

What is the gibbs phase rule for non-reacting systems?

Answer 17

F=C-P+2

Question 18

What is an azeotrope?

Answer 18

Composition in liquid and vapour
phase is identical. Cannot separate by
distillation.

Question 19

What is a stage?

Answer 19

Device or a combination of devices in which two essentially
immiscible phases are brought into intimate contact to allow mass
transfer between them, and then are mechanically separated.

Question 20

What is an equilibrium stage?

Answer 20

Phases are
assumed to be in equilibrium with
each other at separation.

Question 21

Describe the relationship between a substance’s volatility and its boiling point?

Answer 21

The lower the boiling point, the more volatile the substance is.

Question 22

When the does the mole fraction of A in vapour phase = mole fraction of A in liquid phase?

Answer 22

When the system is an azeotrope

Question 23

If xa = ya, can A and B be separated using vaporization?

Answer 23

No, because the composition of the liquid and vapour are the same

Question 24

What is the rate of separation limited by?

Answer 24

The rate of mass transfer

Question 25

Is there mass transfer for a system at equilibrium?

Answer 25

No

Question 26

What is the goal of separation processes?

Answer 26

Enhance the rate of mass transfer of certain species relative to others to effect a concentration or enrichment of components.