Solutions Molarity = concentration term used to describe an amount of solute dissolved in a given amount of solvent. Concentrated solution = contains large quantities of solute dissolved in solvent Dilute solution = contains small amounts of solute dissolved in solvent

Stock Solutions vs. Diluted Solutions A stock solution tends to be a more concentrated solution that is kept and used to make more diluted solutions. A stock solution can be purchased or made by dissolving a solid solute into the solvent. You can always dilute a more concentrated solution. You CANNOT make a dilute solution more concentrated!

Preparation of Stock Solution You need to prepare 100mL of a 0.125M CuSO4 stock solution. How would you make this solution? Calculate the number of grams of CuSO4 needed. In words, describe in a stepwise process how to make the solution. These must be specific to the particular solution you are making.

Preparation of Stock Solution Weigh out 2.00 grams of copper(II) sulfate Fill a 100. mL volumetric flask approximately ½ way with water. Add in the solute (2.00 g) Agitate until solute is completely dissolved. Add water (solvent) until the solution reaches the line (score mark).

Diluting a Stock Solution To make a solution LESS Concentrated: Add solvent Number of moles of solute does not change Use formula: M1V1 = M2V2

Preparation of diluted solution You would like to now make 25mL of 0.0150M CuSO4 solution. How would you make this solution using the stock solution prepared? Use this formula: M1V1 = M2V2 to calculate the volume of the stock solution you would need.

Dilution Mstock = 0.125 M Vstock = ?? Mdiluted = 0.0150M Vdiluted = 25 mL Vstock = 3 mL How was the dilution prepared?

Preparation of diluted solution Take 3.00 mL of the stock solution using a volumetric pipette. Add to a 25 mL volumetric flask. Dilute with water until the solution reaches the line. Mix the solution.