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 ID: 643987
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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 doneSlide2
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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 volumeSlide4
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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 mLSlide5
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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