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

4C.

density of solid or liquid

S.G. = --------------------------

density of water at 4C

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

solved by ratio and proportion.

1.42 g

1 mL

------= ----------

xg

200 mL

(x g)(1 mL) = (1.42 g)(200 mL)

(1.42 g)(200 mL)

x g = ----------------

1 mL

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.

MD0837

8-3

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