Density and specific gravity are both measures of how much mass is contained in a given volume. However, they are not the same thing. Density is a measure of mass per unit volume, while specific gravity is a dimensionless quantity that compares the density of a substance to the density of a reference substance.
The reference substance that is most commonly used for specific gravity is water at a standard temperature and pressure. This means that the specific gravity of water is always 1.0.
The density of a liquid is numerically equal to its specific gravity when the liquid is compared to water at a standard temperature and pressure. This is because the density of water at a standard temperature and pressure is 1.0 g/cm<sup>3</sup>.
For example, the density of ethanol is 0.789 g/cm<sup>3</sup>. When ethanol is compared to water at a standard temperature and pressure, its specific gravity is 0.789.
However, the density of a liquid is not always numerically equal to its specific gravity. This is because the density of a liquid can change with temperature and pressure. For example, the density of water decreases as the temperature increases. This means that the specific gravity of water will be less than 1.0 at a temperature above 4°C.
In general, the density of a liquid will be numerically equal to its specific gravity when the liquid is compared to water at a standard temperature and pressure. However, the density of a liquid can change with temperature and pressure, so the specific gravity of a liquid may not be numerically equal to its density at other temperatures and pressures.
