1. Which one of these is more concentrated?

2. MOLARITY A measurement of the concentration of a solution
Molarity (M) is equal to the moles of solute per liter of solution M = mol / L

3. Steps to Answer Problems
1. If you are given grams of the solute, you MUST convert into moles. (Divide by molar mass) If given moles go to step two.
2. If you are given milliliters of the solute, you MUST convert into liters. (Divide by 1000) If given liters go to step three.
3. Use the formula to solve:
Molarity (M) = Moles of solute Liters of solution

4. I DO:
Calculate the molarity of a solution prepared by mixing 12.0 grams of potassium permanganate (KMnO4), in enough water to make a 750 ml solution.

5. We Do:
Calculate the molarity of a solution made with 23.8 grams of iron chloride, FeCl3, dissolved in mL of water.

6. You Do:
What is the molarity, M, of a solution containing 45.5 grams of solute (KCl) in enough water to make a 3.5 L solution?

7. Think about this
What could you do if you have one concentration (M) of a solution and you need a less concentrated solution?

8. You are right! You would dilute it!
Dilutions of stock solutions are frequently used to make solutions of any desired molarity.
To dilute a solution means to add more solvent without the addition of more solute. (The resulting solution must be thoroughly mixed to ensure homogeneity.)

9. Equation for Dilution M1V1 = M2V2 M1= Molarity of starting solution
V1 = Volume of starting solution
M2= Molarity of final solution
V2= Volume of final solution

10. I DO:
You have 53 ml of a 1.5 M solution of NaCl, but 0.8 M solution is needed. How many ml should you add?

11. We Do:
50 ml of a solution are diluted to a volume of 100 ml. The concentration of the diluted solution is 2 M. What was the concentration of the original solution?

12. YOU DO:
What is the molarity of the solution that results from diluting 20.0 ml of a 4.00M solution to a new volume of 68.3 ml?

13. Add more solvent to the solution
Think about this!!!!
What could you do if you have one concentration (M) of a solution and you need a less concentrated solution?
Add more solvent to the solution

14. You are right! You would dilute it!
Dilutions of stock solutions are frequently used to make solutions of any desired molarity.
To dilute a solution means to add more solvent without the addition of more solute. (The resulting solution must be thoroughly mixed to ensure homogeneity.)

15. Equation for Dilution M1V1 = M2V2 M1= Molarity of starting solution
Final solution
Starting solution
M1V1  =  M2V2
M1= Molarity of starting solution
V1 = Volume of starting solution
M2= Molarity of final solution
V2= Volume of final solution

16. I DO:
You have 53 ml of a 1.5 M solution of NaCl, but 0.8 M solution is needed. How many ml should you add?
M1V1  =  M2V2
(1.5) (53) = 0.8X
79.5 = 0.8X
99.38 mL = X

17. We Do:
50 ml of a solution are diluted to a volume of 100 ml. The concentration of the diluted solution is 2 M. What was the concentration of the original solution?
M1V1  =  M2V2
X(50) = (100)(2)
50X = 200
X = 4 M

18. YOU DO:
What is the molarity of the solution that results from diluting 20.0 ml of a 4.00M solution to a new volume of 68.3 ml?
M1V1  =  M2V2
(4)(20) = X(68.3)
80 = 68.3X
1.17 M = X