1. Practical Concentrations
Alcohol
-proofing is a concentration of drinking alcohol
-a proof is based on 200 and is a concentration to
water
-a hydrometer can be used to measure
concentration by measuring the density of a
solution
-the percentage of rubbing alcohol is based on
volume

2. Practical Concentrations
EPA limits for toxins are measured in ppm or ppb.
-in drinking water, less than ppm/15 ppb for
lead
-arsenic = less than 0.010ppm/10 ppb
-fluoride = less than 4 ppm
-mercury = less than ppm/2 ppb
-nitrates = less than 10 ppm

3. Practical Concentrations
Dilutions
-in order to dilute a solution, we use the following
equation:
-C1 = original, stock solution
-V1 = the volume needed to make your new
concentration
-C2 = desired concentration
-V2 = desired volume (add water to V1 until V2 is
desired)
Note: units must be the same on both sides!

4. Dilution Practice Answer the following questions:
Note: 1 cm3 H2O = 1 mL of H2O = 1 g of H2O
1. How do you prepare a 250.-ml of a 2.35 M HF dilution from a 15.0 M stock solution?
2. How do you prepare 500.-ml of a 1.77 M H2SO4 dilution from an 18.0 M H2SO4 stock solution?