1. Concentration/Dilution

2. Solution Preparation Preparing a solution of Sodium Chloride (NaCl)
Solute= Sodium Chloride (solid)
Solvent = water (distilled)
We know that we define solutions based on CONCENTRATION (Molarity)
Molarity (M) - the number of moles of solute dissolved in a certain volume of the total solution. (mol/L)

3. Solution Preparation 0.500L x 0.25 mol 0.25mol = 0.25 mol/L 1 L
Preparing Solution
preparing a 500ml of a 0.25mol of NaCl solution
need to calculate how many grams of NaCl we need for the solution
0.500L x 0.25 mol
0.25mol = 0.25 mol/L
1 L
500mL x L
=0.125 mol NaCl
1000mL
= 0.500L
0.125 mol x 58.43g
1 mol
= 7.304g of NaCl

4. In Lab you need these materials
sodium chloride
scoop
scale
glass stir rod
distilled water
volumetric flask

5. Making Up a Standard Solution
wavEKA0

6. Prepare a 250mL of a 0.500mol/L solution of Sodium Chloride
Step #1: Determine the mass of Sodium Chloride required

7. Prepare a 250mL of a 0.500mol/L solution of Sodium Chloride
Step 2: place the amount in a 250mL volumetric flask. If difficult add the amount to a beaker.
Step 3: Distilled water is added until the flak is about half full.
Step 4: The flask is shaken until the solid has completely dissolved
Step 5: Distilled water is again added until the flask is full to the mark.

8. Calculating the Percent Concentration.
Volume Percentage (% V/V)
Used for solutions of a liquid in a liquid
Volume % of solute = Volume of solute
Examples:
Percentage of acetic acid in vinegar
Percentage of alcohol in beer and spirits
x 100%
volume of solution

9. Calculating the Percent Concentration.
Mass Percentage (% m/m)
Used for solid solutions --> alloys
Mass % of solute = mass of solute
Examples:
Percentage of copper in brass
Iron in stainless steel or silver
x 100%
mass of solute & solvent

10. Calculating the Percent Concentration.
Weight volume Percentage (% m/v)
Usually used in household products when a mass of a solute is dissolved in the solvent which is a liquid.
Mass volume % = weight of solute(g)
Examples:
Percentage of caffeine in a cup of tea
x 100%
volume of solvent (mL)

11. Dilution
Dilution: increasing the amount of solvent and the concentration decreases.
common way to take a stock solution & create other solutions.
c = n
remains constant V
decreases (b/c volume increases)
increases (b/c water is added)

12. Dilution
During a dilution, the concentration of a solution decreases due to an increase of its volume. The amount of solute remains unchanged
Dilution Equation
CiVi = CfVf

13. Dilution
Calculate the volume of a 0.10M solution made from 200mL of 0.30M NiCl2
CiVi = CfVf

14. Add 400mL of water ---to finally end up with 600mL Solution
Dilution
Calculate the volume of a 0.10M solution made from 200mL of 0.30M NiCl2
CiVi = CfVf
Add 400mL of water ---to finally end up with 600mL Solution