How to calculate and measure specific gravity. If the density of a substance is known, to calculate the specific gravity of a substance simply divide the density of the substance by the density of water or air. Because the density of water is 1000 kg/m3 or 1 g/cm3, it is simple to calculate.
How to Use Specific Gravity?
Specific gravity is a measure of the relative density of a substance compared to water. It is used to determine the amount of a substance in a given volume. Knowing how to use specific gravity can be helpful when measuring liquids or solids.
When measuring liquids, the specific gravity is determined by measuring the liquid’s density and then dividing it by the density of water. This can be done by using a hydrometer, a device which measures the density of liquids. A hydrometer is filled with the liquid to be measured and its density is then read from a scale. The density is divided by the density of water and the result is the liquid’s specific gravity.
When measuring solids, the specific gravity is determined by measuring the solid’s mass and then dividing it by the mass of an equal volume of water. This can be done by using a pycnometer, a device which measures the mass of a sample. The sample is placed into the pycnometer and its mass is then read from a scale. The mass is divided by the mass of an equal volume of water and the result is the sample’s specific gravity.
Specific gravity can also be used to measure the concentration of a solution.