Density

The density of a substance is defined as its mass per unit volume.

Density (ρ) = mass (m)/ Volume (V)

 

Unit of density:

In the cgs system: gcm^-3

In SI: kgm^-3. (1gcm^-3 = 1000 kgm^-3)

 

Relative Density

The relative density (RD) of a substance is the ratio of the density of the substance to the density of water at 4⁰C. From the definition, the relative density of a substance is given as      

RD = Density of the substance / Density of water at 4⁰C.

Thus, relative density is also defined as the ratio of the mass of the substance to the mass of an equal volume of water at 4⁰C.