1. Concentrations of Solutions
Section 4.5
Concentrations of Solutions

2. Concentration
Amount of solute dissolved in a given quantity of solvent or solution
Amount of solute = Concentration

3. Molarity (M) Concentration of a solution moles of solute
Liters of solution
Molarity (M) =

4. Converting the volume of the solution to liters:
SAMPLE EXERCISE 4.11 Calculating Molarity
Calculate the molarity of a solution made by dissolving 23.4 g of sodium sulfate (Na2SO4) in enough water to form 125 mL of solution.
Solve: The number of moles of Na2SO4 is obtained by using its molar mass:
Converting the volume of the solution to liters:

5. Concentration of Electrolytes
For ionic compounds (S.E.):
Look at chemical formula for relative concentration of ions
Ex 1: 1.0M NaCl is 1.0M Na+ and 1.0M Cl-
Ex 2: 1.0M Na2SO4 is 2.0 M Na+ and 1.0M SO42-

6. Process of lowering the concentration of a solution by adding water
Dilution
Process of lowering the concentration of a solution by adding water

7. Quick Calculation
M1V1 = M2V2
*Sets the moles equal to each other

8. Dilution Problem We want: 0.600 M MgSO4
We have: 15.0 mL of 1.50 M MgSO4
How much water should be added to what we have?

9. Homework
Molarity/Dilution Worksheet