# Introduction to Chemical Engineering Processes/Notation

## Contents

## A Note on Notation[edit]

## Base Notation (in alphabetical order)[edit]

: Molarity of species i in stream n a, b, c, d: Stoichiometric coefficients. A: Area C: Molar concentration (mol/L) K: Equilibrium coefficient m: Mass MW: Molecular Weight (Molar Mass) n: Moles n: Number of data points (in statistics section) N: Number of components P: Pressure r: Regression coefficient R: Universal gas constant T: Temperature v: Velocity V: Volume x: Mole fraction in theliquid phaseOR Mass fraction^{[1]}X: (molar) extent of reaction y: Mole fraction in thegas phasez: Overall composition Z: Compressibility

- ↑ Unless specified explicitly,
**assume that a given percent composition is in terms of the overall flowrate**. So if you're given a flowrate in terms of kg/s and a compositoin of 30%, assume that the 30% is a mass fraction. If a given equation requires one or the other, it will explicitly be stated near the equation which is necessary.

## Greek[edit]

: Density : Sum

## Subscripts[edit]

If a particular component (rather than an arbitrary one) is considered, a specific letter is assigned to it:

- [A] is the molarity of A
- is the mass fraction of A

Similarly, referring to a specific stream (rather than any old stream you want), each is given a different number.

- is the molar flowrate in stream 1.
- is the molar flow rate of component A in stream 1.

**Special subscripts:**

If A is some value denoting a property of an *arbitrary* component stream, the letter i signifies the arbitrary *component* and the letter n signifies an arbitrary *stream*, i.e.

- is a property of
*stream*n. Note is the molar flow rate of stream n. - is a property of
*component*i.

The subscript "gen" signifies generation of something inside the system.

The subscripts "in" and "out" signify flows into and out of the system.

## Embellishments[edit]

If A is some value denoting a property then:

denotes the *average* property in stream n

denotes a *total flow rate* in steam n

denotes the flow rate of component i in stream n.

indicates a data point in a set.

is a property of *pure component* i in a mixture.

## Units Section/Dimensional Analysis[edit]

In the units section, the generic variables L, t, m, s, and A are used to demonstrate dimensional analysis. In order to avoid confusing dimensions with units (for example the unit m, meters, is a unit of length, not mass), if this notation is to be used, use the *unit equivalence* character rather than a standard equal sign.