1. Molarity = Molarity ( M ) moles solute liters of solution
Molarity is defined as the amount of moles of a compound dissolved in an amount of solvent (usually water).
It can be solved with the equation:
Molarity ( M ) =
moles solute
liters of solution

2. Molarity – What is it? A measure of how concentrated a solution is.
Think about making Kool-Aid.
What makes Kool-Aid more delicious?
The more sugar you add, the sweeter the solution gets.
Adding more moles of sugar, without changing the volume makes the Molarity “Concentration” Increase

3. Molarity Practice
1) 80.5 grams of sodium chloride is dissolved in 3.5 Liters. Determine the Molarity.
2) 125 grams of Calcium Fluoride is dissolved in 250 mL of water. Solve for the Molarity.

4. 2.80 M = x mol / 0.500 L = 1.40 mol 1.40 mol 166 g KI 1 mol KI
What mass of KI is required to make 500. mL of
a 2.80 M KI solution?
2.80 M = x mol / L = 1.40 mol
1.40 mol
166 g KI
1 mol KI
= 232 g KI
12.3

5. Dilution of Solutions
Dilution is the procedure for preparing a less concentrated solution from a more concentrated solution.
When you want to dilute a solution, what happens to the number of moles present in the solution?
Do they increase?
Decrease?
Stay the same?
Stay the same. 5

6. Since moles are constant before and after dilution, we can use the following formula for dilution calculations.
M1V1=M2V2
M1 = Starting Molarity , V1 = Initial Volume of solution
M2 = Final Molarity, V2 = Final Volume of solution

7. Example
Describe how you would prepare 800mL of a 2.0M H2SO4 solution, starting with a 6.0 M stock solution.
MiVi = MfVf
6.0M x Vi = 2.0M x 0.800L
Vi = 1.6M x L/ 6.0M
Vi = 0.26L
How much water will need to be added?

8. How would you prepare 60.0 mL of 0.2 M
HNO3 from a stock solution of 4.00 M HNO3?
MiVi = MfVf
Mi = 4.00
Mf = 0.200
Vf = 0.06 L
Vi = ? L
Vi =
MfVf Mi =
0.200 x 0.06
4.00
= L = 3 mL
3 mL of acid
+ 57 mL of water
= 60 mL of solution
4.5

9. Solution Stoichiometry
We use the same ideas when we converted from grams of one compound to grams of another, except we are in mL of solution instead of grams.
Use the Molarity equation: M = mol/L
Use stoichiometry to convert moles of one compound to moles of the other compound.
X grams
X mol X grams
Y mol
X mol
Y grams
Y mol

10. Solution Stoich Practice
How many mL of 2.00 M Hydrobromic acid, when reacted with aluminum hydroxide, will be required to produce 60.0 grams of water in the acid base reaction?
___HBr +___Al(OH)3  ___H2O + ___ AlBr3 3 1 3 1
60.0 g H2O
1 mol H2O g H2O
3 mol HBr 3 mol H2O
= 3.33 mol HBr
3.33 mol HBr
2.00 M HBr =
= 1.67 mL HBr
X ml HBr