Density
The mass of a substance contained in a unit volume, a characteristic intensive property of each material.
Formula / equation
ρ = m / V
Unit
g/cm³
In depth
Density depends on both the mass of the constituent particles and how tightly they pack, so it falls sharply on melting and dramatically on boiling. It varies with temperature because thermal expansion changes volume, so quoted values always cite a reference temperature, usually 20 °C or 25 °C.
Examples in the real world
Water is 1.00 g/cm³ at 4 °C, ethanol 0.789 g/cm³, mercury 13.53 g/cm³, and osmium 22.59 g/cm³.