SPECIFIC GRAVITY AND DENSITY
a. Specific gravity is a method of measuring density. Density is the amount of
matter in a given volume, that is, D = g/mL. Specific gravity is a ratio between the mass
of a given volume of any substance and the mass of an equal volume of pure water at
density of solid or liquid
S.G. = --------------------------
density of water at 4C
NOTE: When determining specific gravity, the units divide out. Hence, specific
gravity has no unit of report.
b. Since 1 milliliter of pure water at 4C has a mass of 1 gram, specific gravity is
equal to the numerical value of the mass in grams of one milliliter of any substance.
Materials less dense than water have a specific gravity of less than one, whereas
materials more dense than water have a specific gravity greater than one.
c. Example. The density of 200 mL of HNO3 solution is 1.42 g/mL. What is the
weight of that solution?
Solution. Restating the problem, one milliliter of this solution weighs 1.42
grams; how much would 200 mL of the same solution weigh? This problem can be
(x g)(1 mL) = (1.42 g)(200 mL)
(1.42 g)(200 mL)
x g = ----------------
x g = 284 g
The 284 grams represents the total weight of the solution and not just the
weight of the HNO3 present in the solution.