The relative density is the ratio of the mass of the substance in air at 20 °C to that of an equal volume of water at the same temperature. The term “relative density” is equivalent to the formerly used term “specific gravity determined at 20 °C”.
Procedure: Use pycnometer.
Use a pycnometer of suitable form of a capacity of not less than 5 mL.(10ml).
Weigh accurately the empty, dry pycnometer (Wt1).
Then fill the pycnometer with the test liquid brought previously to a temperature of about 20°C.
Hold the filled pycnometer at a temperature of 20 ± 1 °C, adjust the liquid to the mark using, and weigh accurately.(Wt2)
Remove the liquid, clean and dry the pycnometer, repeat the measurement with carbon-dioxide free water and weigh accurately.(Wt3)
The ratio of the weights of the test liquid and of water gives the relative density
