Diluting a Solution
• Most solutions are stored in concentrated
form and diluted for use when required.
• To dilute to the required concentration we
must extract the number of moles required
from the stock solution and place them in
the new flask.
• Fill it with water and we are done
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• The number of moles does not change when you
dilute the solution, therefore:
• Since n = Cv in both beakers, we can write the
relationship as :
• Civi = Cfvf
Ci = Concentration of the initial solution
vi = volume of the initial solution
Cf = Concentration of the final solution
vf = volume of the final solution
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EXAMPLE 1
•
What volume of 12.4 mol/L
hydrochloric acid is required to
prepare 2.00 L of 0.250 mol/L
solution.- note: whenever you want
to prepare something, this will be a
final concentration or volume
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ANSWER

Civi = Cfvf
12.4 M (v) = 2.00 L x 0.250 M
v= (2.00L) x (0.250M/12.4M)
v = 0.0403 L or 40.3 mL
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EXAMPLE 2
•
What is the concentration of
the diluted acetic acid if 200
mL of 17.4 M is pipette into
a 500 mL flask and brought
up to the full volume?
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ANSWER #2

Civi = Cfvf (note:200mL=0.200L)
17.4 M x 0.200 L = Cf x 0.500 L
Cf = 6.96 M
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