7/20/2016
Review

Standard Solution = a solution for which
the precise concentration is known
Used in research laboratories and industrial
processes
 Used in chemical analysis and precise control
of chemical reactions

Solutions & Solubility
Solution Preparation by dilution
Preparing a Solution by Dilution

Dilution = the process of decreasing the
concentration of a solution, usually by adding
more solvent
Solution Preparation

Equipment needed to prepare a standard
solution:

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
Graduated Pipettes and bulbs
Volumetric flask
Stock Solution = a solution that is in stock
or on the shelf (i.e., available); usually a
concentrated solution
Graduated & Volumetric Pipettes and Bulb
transfer small quantities of liquid
The Formula
the number of moles (n) does not change
when more solvent is added to a solution; only
the concentration changes
 therefore, ni (initial) = nf (final)
 If a solution is diluted from V1 to V2, the molar
concentration of that solution changes
according to the following equation:
 C1 V1 = C2 V2


** remember: n = C X V **
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7/20/2016
The Variables
C1V1 = C2V2
 C1 = initial concentration of stock
solution
 V1 = volume of stock solution to be
transferred
 C2 = final concentration of dilute
solution
 V2 = final volume of dilute solution
Example
The Procedure
Now you try….

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Remove the calculated V1 amount of your stock solution
using a pipette.
Place that volume into a clean, dry volumetric flask of the
volume needed for your diluted solution
Add distilled water to the mark of the volumetric flask
Label the flask with the new solution concentration


How do you prepare 250 mL of a 0.01 mol/L
solution from a stock solution of 0.1 mol/L?
 The Calculations: C1V1 = C2V2
Make 50.0mL of 0.150M NaCl solution from your 0.300M
stock solution
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