ratio of Volumestock /Volumediluted is known as the dilution factor.
For example, if 10 mL of a stock solution is diluted to a final volume
of 100 mL, the dilution factor is 10 to 100 (written lO/lOO), or 1
to 10 (written 1/10). From the equation above, you can see that multiplying
the molarity of the stock solution by the dilution factor will give
the molarity of the diluted solution.
that a dilution factor gives the volume of the stock solution contained
in the total volume of the diluted solution. This is not the same
as saying 10 parts to 100 parts, however. It is 10 parts in 100 parts.
When preparing dilutions, it is more precise to use a pipet with a
tolerance of 0.02 mL than a graduated cylinder. In this laboratory
however, dilutions are prepared using a graduated cylinder, since
pipeting is not presented until a later laboratory exercise.
While molarity is widely used, there are other common ways to express
concentration. Percent concentration, molality, normality and mole
fractions are some examples.
Percent concentration is defined as the weight or volume of one substance
per total weight or volume of the solution, times 100. There are several
variations of percent concentrations. For example, in a weight percent
(w /w % ) solution, the weight of one substance is measured per weight
of solution. In a volume percent (v/v %) solution, the volume of one
substance is measured per volume of solution. Finally, in a weight-volume
percent (w/v %) solution, the weight of one substance is measured
per volume of solution.
general equation for percent concentration is:
calculate the amount of a solute that must be weighed to produce a
specific percent concentration, rearrange the equation as shown below.