1. Concentration
Mass Percent
PPM
PPB
Volume Percent

2. Concentration of Solutions
The concentration of a solution expresses the amount of solute dissolved in a given quantity of solvent or solution
A dilute solution contains a relatively small amount of dissolved solute.
A concentrated solution contains a relatively large amount of solute.

3. Concentration - Mass Percent Solution
Mass percent expresses the concentration of solution as the mass of solute in a given mass of solution.
The mass of solution = mass of solute + mass of solvent

4. Examples of Mass Percent Problems
What is the mass percent of sodium hydroxide in a solution that is made by dissolving 8.00 g NaOH in 50.0 g H2O?
What masses of potassium chloride and water are needed to form g of 5.0% solution?
A 34.0% sulfuric-acid solution has a density of g/mL. How many grams of H2SO4 are contained in 1.00 L of this solution?

5. Concentration – PPM (Parts per Million)
ppm expresses the concentration of solution as the mass of solute in a given mass of solution.
*The mass of solution = mass of solute + mass of solvent
ppm is typically used for very small concentrations

6. Examples of ppm Problems
A mL sample of drinking water is found to contain g of lead. What is the concentration in ppm?
A 1.0 L air sample contains 4.25 × 10−4 g of CO2. Express the concentration of CO2 in the air in ppm. The density of atmospheric air is 1.29 g/L at the Earth’s surface.
A mL sample of boiler feed water has a carbonate concentration of 45 ppm. What is the mass of carbonate ion in the sample? The density of the feed water is g/L at 22.0°C.

7. Concentration – PPB (Parts per Billion)
ppm expresses the concentration of solution as the mass of solute in a given mass of solution.
*The mass of solution = mass of solute + mass of solvent
ppb is typically used for very small concentrations

8. Examples of ppb Problems
What is the concentration, in ppb, of PCBs in a chemical spill if there is mg in kg of soil?
What is the mass of nickel, in mg, in 2.4 kg of propanol if the concentration is 20 ppb?
What is the concentration, in ppb, if g of CaCl2 is dissolved in 1.50 kg of water?

9. Concentration – Volume Percent
This form of concentration can be used for solutions formed from two liquids or two gases
Volume percent is the volume of the solute in 100 mL of solution

10. Volume Percent continued
If a bottle of wine is 12% alcohol by volume
there are 12 mL of alcohol per 100 mL of wine
Note: liquid volumes are not necessarily additive due to intermolecular forces between the molecules of solute and solvent and the shape of the molecules
To make a 60% solution of isopropyl alcohol add enough water to 60 mL of the alcohol to bring the total volume of the solution to 100 mL
The volume of water added may not be 40 mL

11. Examples of %v/v Problems
Determine the volume percent of the following:
37.5 mL of butanol dissolved in enough ethanol to make a 300 mL solution
6.0 mL of methanol dissolved in enough water to make a 25.0 mL solution
50.0 mL isoamyl alcohol dissolved in enough acetone to make an 800 mL solution