Solutions & Solubility

Solution Preparation by dilution

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

Preparing a Solution by Dilution Dilution = the process of decreasing

the concentration of a solution, usually by adding more solvent

Stock Solution = a solution that is in stock or on the shelf (i.e., available); usually a concentrated solution

Equipment needed to prepare a standard solution: Graduated Pipettes and bulbs Volumetric flask

Solution Preparation

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 **

The VariablesC1V1 = 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 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

The Procedure 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

Now you try…. Make 50.0mL of 0.150M NaCl solution from

your 0.300M stock solution