Relative Density

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

Relative Density $=\frac{\text { Mass }}{\text { Volume }}$

S.I. unit of density is kg/m³

The relative density of a substance is the ratio of its density to that of water

Relative Density $=\frac{\text { Density of substance }}{\text { Density of water at 4ºC }}$

Relative density of a substance $=\frac{\text { Mass of the substance }}{\text { Volume of the substance }} \times \frac{\text { Volume of water }}{\text { Mass of water }}$

If we take equal volumes of water and substance then

Relative Density of substance $=\frac{\text { Mass of substance }}{\text { Mass of water }}$

The relative density of a substance expresses the heaviness or density of the substance in comparison to water.

For Example : Relative density of iron is 7.8 means iron is 7.8 times heavy as an equal volume of water.