Units of Concentration (v/v, w/v, w/w and
ppm) 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 = V_{solute}
X 100% V_{solution} 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
v/v concentration? 
% 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% H_{2}O_{2} topical antibiotic
solution means that there is 3 grams of H_{2}O_{2} 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 10^{6} parts 1 part per billion (ppb): 1 part out of 1 X 10^{9} parts 1 part per trillion (ppt): 1 part out of 1 X 10^{12} 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
microgram 10^{6} mL 1000 L 1 L 1 kg 1 g 
Example #2 Dissolved O_{2} in water shows a concentration of 250 mL of water At SATP and 2.2 mg of O_{2}. 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 Go to the Concentration Unit Calculations Other than Molarity Workshsheet 