October 26, 2012
Chapter Five: Solutions
Lesson Three: Dilution
Dilution
To dilute a solution means to reduce its concentration by adding more solvent. October 26, 2012
Preparing a Solution
A common way to prepare a solution is to take a concentrated solution and add water to it. Calculations Involving Dilution Since solutions are diluted by adding water, the amount of solute (moles) in the concentrated and dilute solution is the SAME
amount of moles is the same
October 26, 2012
Dilution Formula
CiVi = CfVf
Ci and Vi are the concentration and volume of the more concentrated solution (sometimes called the stock solution) Cf and Vf are the concentration and volume of the dilute solution
Example # 1
Water is added to 0.200 L of a 2.40 mol/L solution of ammonia until the 7inal volume is 1.000 L. What is the concentration of the diluted solution?
October 26, 2012
Example # 1Answer CiVi=CfVf
Cf = CiVi
Vf
Cf = 2.40 mol/L x 0.200 L
1.000 L
Cf = 0.480 mol/L
Example # 2
A student is asked to dilute some concentrated HCl(aq) (36% m/m) to make 4.0L of 10% m/m. What volume of stock solution should the student measure?
October 26, 2012
Example #2 Answer CiVi = CfVf
Vi = CfVf
C
i
Vi = 10% x 4.00 L
36%
Vi = 1.1 L
How would this student do this?
1. Measure 1.1 L of 36% HCl
2. Add it to a 4.0 L :lask.
3. Add water until the total volume is 4.0 L.