|Units of Concentration (v/v, w/v, w/w and
These units of concentration are most often seen and used with commerical products. Expect for 'ppm' they are not used often in the lab.
|Percent Concentration Volume/Volume (v/v): used with 2 liquids.|
| % Concentration = Vsolute
eg. 5 mL of vinegar are dissolved in 100 mL of vinegar solution. What is its v/v concentration.
% concentration =
5 mL of vinegar X 100% = 5%
|Example #1 A photographic stop bath contains 140
mL of pure acetic acid in a 500 mL bottle of solution. What is the
| % concentration
= 140 mL of vinegar X 100% = 28%
500 mL of solution
|Percent Concentration Weight/Volume (w/v): used with one solid and one liquid|
|This means there is a certain mass, in grams, in every 100
mL of solution.
|eg. a 3% H2O2 topical antibiotic
solution means that there is 3 grams of H2O2 in every
100 mL of solution.
|Percent Concentration Weight/Weight (w/w): used with two solids|
|Useful when dealing with alloys of precious metals.
|eg. A ring with a mass of 12.0 grams contains 11.1 grams
of pure silver. What is the w/w%?
% concentration = 11.1 grams
of solute X 100% = 92.5% w/w of silver
|Parts per Million Concentration (ppm)|
|Environmental solution are often very low in concentration.
We often use terms like:
1 part per million (ppm): 1 part out of 1 X 106 parts
1 part per billion (ppb): 1 part out of 1 X 109 parts
1 part per trillion (ppt): 1 part out of 1 X 1012 parts
1 ppm = 1 drop in a full bathtub
|We express ppm concentration in a variety of units depending
on what we need to use. But they are all interrelated.
|ppm = 1 g
= 1 g
= 1 mg
= 1 mg = 1
106 mL 1000 L 1 L 1 kg 1 g
|Example #2 Dissolved O2 in water shows a concentration of 250 mL of water At SATP and 2.2 mg of O2. What is the concenrtaion in ppm?|
|ppm concentration = 1 mg =
2.2 mg = 8.8 mg/L = 8.8 ppm
1 L 0.25 L
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Concentration Unit Calculations Other than Molarity Workshsheet