
Weight/Volume PercentAnother variation on percentage concentration is weight/volume percent or mass/volume percent. This variation measures the amount of solute in grams but measures the amount of solution in milliliters. An example would be a 5%(w/v) NaCl solution. It contains 5 g of NaCl for every 100. mL of solution.
Because of the different units in the numerator and denominator, this type of concentration is not a true percentage. It is used as a quick and easy concentration unit because volumes are easier to measure than weights and because the density of dilute solutions is generally close to 1 g/mL. Thus, the volume of a solution in mL is very nearly numerically equal to the mass of the solution in grams.
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