<P> Specific gravity is the ratio of the density of a substance to the density of a reference substance ; equivalently , it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume . Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance . The reference substance for liquids is nearly always water at its densest ( at 4 ° C / 39.2 ° F ) ; for gases it is air at room temperature ( 20 ° C / 68 ° F ) . Nonetheless , the temperature and pressure must be specified for both the sample and the reference . Pressure is nearly always 1 atm ( 101.325 kPa ) . </P>
<P> Specific gravity is the ratio of the density of a substance to the density of a reference substance ; equivalently , it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume . Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance . The reference substance for liquids is nearly always water at its densest ( at 4 ° C / 39.2 ° F ) ; for gases it is air at room temperature ( 20 ° C / 68 ° F ) . Nonetheless , the temperature and pressure must be specified for both the sample and the reference . Pressure is nearly always 1 atm ( 101.325 kPa ) . </P>
specific gravity is a comparison of the weight of a substance to the weight of an equal volume of
specific gravity is a comparison of the weight of a substance to the weight of an equal volume of
a reference substance
a reference substance