In this section, definitions are what we'll spend time learning.  When you first start taking your chemical engineering courses, some of the terms, like density, will be familiar to you, while others, like Raschig rings (encountered in Mass Transfer and Separations) will not. As you encounter the new terms it is a good idea to spend some time trying to memorize what they mean and what units may be associated with them.

We'll begin with definitions that are used to describe the physical properties of something.  These definitions include weight, force, volume, density, and many others.  Look at the units so you can get an idea of how these definitions are related.
In this section, and throughout these webpages, the symbol [=] will be used as a shorthand notation for "has units of"

Density is the mass per unit volume of a substance.
    rho [=] kg/m3, g/cm3, lbm/ft3

Specific volume is the volume per unit mass of a substance.
    Vhat [=] m3/kg, cm3/g, ft3/lbm

Specific gravity is the ratio of the substance's density to that of water.
    S.G. [=] (no units)
    S.G. = rho/rhoref

    rH2O = 1.000 g/cm3 = 62.43 lbm/ft3

2007 Arizona Board of Regents for The University of Arizona