Jason Eardley
 | Vocabulary |
density specific gravity |
| Specific gravity = | density of substance density of reference substance |
Specific gravity was defined because it's convenient to have a unitless measure of density. The reference substance for solids and liquids is usually water at 4°C. At that temperature, water has a density of 1.0000 g/mL. So if you know the density of a substance in g/mL, for most practical purposes that's numerically equal to the specific gravity.
To find the specific gravity of the PCB, then, you'll need to have the mass (in g) of a given volume (in mL) of PCB.