Solution. When determining the final dilution of a series of dilutions, use each
dilution as a multiplicative factor. The resulting product is the final dilution.
1
3
21
6
--X -- X --X -- = --------
10 5 15 2
1500
Express the dilution in lowest terms.
1:250
c. Example 3. A 5 mol/L solution of HCl is diluted 1:5. The resulting solution is
diluted 1:10. Determine the concentration of the final dilution.
Solution. When determining the final dilution of a series of dilutions use each
dilution as a multiplicative factor. The resulting product is the final dilution.
1
1
1
-- X ---- = ----
5
10
50
Once the final dilution has been determined, the original concentration is
multiplied by the dilution to yield the concentration of the dilute HCl solution.
1
5
---- X 5 mol/L = ---- mol/L or, eqivalently, 0.1 mol/L
50
50
6-4.
PREPARATION OF A WORKING SOLUTION FROM A STOCK SOLUTION
In some instances, a laboratory may utilize a stock solution that will be diluted in
order to be used as a working solution. In changing the concentration of the solution, a
basic relationship is employed. This relationship is based on the fact that the amount of
solute remains constant in both solutions and can be expressed as follows: The volume
of the given solution times the concentration of that solution equals the volume of the
resulting solution times the concentration of the second solution. An expression that
describes this relationship is as follows:
MD0837
6-5
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