Material Balances
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- JTF (Just the Facts) videos are the streamlined versions: greenscreen LaTeX equations, clean graphics, minimal narrative. Think efficient and to the point. Each has a companion TFS video.
- TFS (The Full Story) videos include interviews, additional explanation, and equations written on whiteboards. Same math, more context, more personality. Each has a matching JTF version.
- Info Page links lead to definitions, expanded explanations, and related material—because sometimes you really do need to explain it.
- Visuals links contain the greenscreen or whiteboard materials used in the video, for those who like to see the scaffolding.
- Wondering about the titles? See Appendix B: If you have to explain it, it’s no longer funny.
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Introduction
Material balances are applications of the General Balance Equation to mass or moles. They are among the most common calculations in chemical engineering and process design.
Material balances are used to determine stream compositions, flow rates, recycle and purge requirements, reactor conversions, and separation performance. In simple systems they may only require bookkeeping. In more complex systems they become the foundation for reactor modeling, phase-equilibrium calculations, and process design.
This section begins with the general balance framework and then moves through the most common kinds of systems in which material balances are applied.
The General Balance Equation
The videos in the General section introduce systems, control volumes, and the balance framework used throughout the rest of this section. If you are new to balances, start there.
Mixers, Dividers, and Separators
The simplest material balances are around nonreactive unit operations such as mixers, dividers, and separators. These provide the basic bookkeeping tools used throughout process engineering.
Gotta Keep ’Em Separated
Mixer, Divider, and Separator mole balances
Video, Info Page, Visuals
Chemical Reactors
Chemical reactors require material balances that account for chemical reaction. Depending on the problem, the reaction may be described in terms of extent of reaction, fractional conversion, kinetics, or equilibrium.
Fractional Conversion Reactors
These videos introduce reactor balances written in terms of extent of reaction, fractional conversion, yield, and selectivity.
When You Saw It, What Was the Extent of Your Reaction? Part 1
Chemical Reactor Single Reaction, \(\xi\) and \(f_{\mathrm{A}}\)
Video, Info Page, Visuals
When You Saw It, What Was the Extent of Your Reaction? Part 2
Chemical Reactor Multiple Reactions with Example, \(\xi\) and \(f_{\mathrm{A}}\)
Video, Info Page, Visuals
When You Saw It, What Was the Extent of Your Reaction? Part 3
Chemical Reactor Yield and Selectivity
Video, Info Page, Visuals
Kinetic Reactors
These videos introduce reactor balances for systems in which the reaction rate is determined by kinetics, including batch reactors, CSTRs, and PFRs.
How Did You Think I Would React?
Basic Kinetic Reactor Mole Balance
Video, Info Page, Visuals
Wishing Upon a CSTR
Batch, CSTR, PFR
Video, Info Page, Visuals
It’s Totally Tubular, Man!
CSTR, PFR, Batch Example
Video, Info Page, Visuals
Equilibrium Conversion Reactors
These videos treat reactors in which the reaction is assumed to proceed to equilibrium rather than being limited by kinetics.
React But Maintain Your Equilibrium Part 1
Basics of equilibrium reactors
Video, Info Page, Visuals
React But Maintain Your Equilibrium Part 2
Equilibrium reactor example
Video, Info Page, Visuals
Combustion Reactions
Combustion balances are a particularly important class of reacting-system material balances because they combine stoichiometry, gas compositions, excess air, and flue-gas analysis.
Flame On, Torch!
Combustion reactions
Video, Info Page, Visuals
A Combustible Mixture!
Sample combustion reactions
Video, Info Page, Visuals
Process Flowsheets
Real processes often contain recycle, bypass, and purge streams. These make the bookkeeping more interesting and more realistic.
Recycling Before Recycling Was Cool
Basics of recycle
Video, Info Page, Visuals
Leaving Radiator Springs In the Dust
Basics of bypass and a recycle example
Video, Info Page, Visuals
The Symbolic Meaning of Recycling
Analytic solution of a recycle PFD
Video, Info Page, Visuals
Properties of Liquids and Gases
Material-balance calculations often require relationships among mass, moles, volume, pressure, temperature, and composition. These video sets introduce the most common property models used in later calculations.
Liquid Properties
Alcohol and Water DO Mix!
Liquid and Solid Density Calculations
Video, Info Page, Visuals
Gas Properties
These videos introduce ideal-gas and real-gas models, along with mixture rules used in process calculations.
Ideal Gases EXPOSED: Are They Even Real?!!
Basics of \(P V = n R T\)
Video, [Info PageIdealAndRealGasesVideoInfoWebPage.qmd), Visuals
When Getting Gassed Isn’t Ideal, Part 1
Real gas intro
Video, Info Page, Visuals
When Getting Gassed Isn’t Ideal, Part 2
Real gas example
Video, Info Page, Visuals
REAL Gas Mixtures EXPLAINED – Don’t Let This Cost You Points on Your Exam! Part 1
Explanation of Kay’s Rule and DWSIM for real gas mixtures
Video, Info Page, Visuals
REAL Gas Mixtures EXPLAINED – Don’t Let This Cost You Points on Your Exam! Part 2
Example of Kay’s Rule and DWSIM for real gas mixtures
Video, Info Page, Visuals
Multiphase Equilibria
Material balances become especially interesting when multiple phases are present. These video sets introduce phase diagrams, dew and bubble calculations, flash calculations, and equilibrium stage models.
Reading Phase Diagrams
Can You Tell an Azeotrope from a Peritectic? Get Your Phase Diagrams Right! Part 1
Phase Diagrams, Gibbs Phase Rule
Video, Info Page, Visuals
Can You Tell an Azeotrope from a Peritectic? Get Your Phase Diagrams Right! Part 2
Ternary Phase Diagrams, Lever Rule
Video, Info Page, Visuals
Bubble, Dew, and Flash Calculations
Show Some Flash and Dew the Dew with a Little Bubbly!
Graphical BUBL P, DEW P, BUBL T, DEW T, and FLASH calculations
Video, Info Page, Visuals
Oh, Henry!
Gas-Liquid Equilibrium with one condensible component
Video, Info Page, Visuals
Dew Your Bubbles Have Flash? Part 1
Raoult’s law, BUBL P, DEW P
Video, Info Page, Visuals
Dew Your Bubbles Have Flash? Part 2
BUBL T, DEW T
Video, Info Page, Visuals
Dew Your Bubbles Have Flash? Part 3
FLASH, Pxy, Txy
Video, Info Page, Visuals
Using DWSIM to Create Binary Phase Diagrams
DWSIM, Binary Phase Diagrams
Video, Info Page
Equilibrium Separation Stages
These videos apply material balances together with phase-equilibrium relationships to model staged separations such as distillation and liquid-liquid extraction.
The Shocking Truth About Equilibrium Stages—Are You Doing It Wrong? Part 1
Equilibrium Stage Equations
Video, Info Page, Visuals
The Shocking Truth About Equilibrium Stages—Are You Doing It Wrong? Part 2
Distillation Examples: Binary Phase Diagram, Raoult’s law
Video, Info Page, Visuals
The Shocking Truth About Equilibrium Stages—Are You Doing It Wrong? Part 3
Liquid-Liquid Extraction Example
Video, Info Page, Visuals