1. Introduction to Molarity
Chemistry 11
Introduction to Molarity
Lesson 1

2. Prescription drugs in the correct concentration make you better.
In higher concentration they can kill you.

3. Chemists need to make solutions that have precise concentrations

4. Pesticides must be in proper concentrations.
Food additives must be in correct concentrations.
A driver is legally impaired at 0.08 mg/mL blood alcohol content.
Chemists control the concentration of chemicals using the concepts we will develop in this unit.

5. The concentration of a solution tells you how much solute that is dissolved in a given amount of solvent (water).
The molarity is the concentration of a solution.
Molarity = Moles
Litre
moles of NaCl is dissolved in 4.0 L of water, calculate the molarity.
Molarity =

6. The concentration of a solution tells you how much solute that is dissolved in a given amount of solute (water).
The molarity is the concentration of a solution.
Molarity = Moles
Litre
moles of NaCl is dissolved in 4.0 L of water, calculate the molarity.
Molarity = moles
4.0 L

7. The concentration of a solution tells you how much solute that is dissolved in a given amount of solute (water).
The molarity is the concentration of a solution.
Molarity = Moles
Litre
moles of NaCl is dissolved in 4.0 L of water, calculate the molarity.
Molarity = moles
4.0 L
= 0.56 moles/litre
= 0.56 M (Molar)
where M means moles per 1 litre

8. 2. 5. 00 g KOH is dissolved in 250. mL of water, calculate the
g KOH is dissolved in 250. mL of water, calculate the molarity.
Molarity =

9. 2. 5. 00 g KOH is dissolved in 250. mL of water, calculate the
g KOH is dissolved in 250. mL of water, calculate the molarity.
Molarity = 5.00 g

10. 2. 5. 00 g KOH is dissolved in 250. mL of water, calculate the
g KOH is dissolved in 250. mL of water, calculate the molarity.
Molarity = 5.00 g x 1 mole
56.11 g

11. 2. 5. 00 g KOH is dissolved in 250. mL of water, calculate the
g KOH is dissolved in 250. mL of water, calculate the molarity.
Molarity = 5.00 g x 1 mole
56.11 g
0.250 L

12. 2. 5. 00 g KOH is dissolved in 250. mL of water, calculate the
g KOH is dissolved in 250. mL of water, calculate the molarity.
Molarity = 5.00 g x 1 mole
56.11 g
0.250 L
= M

13. 3. How many moles are there in 205. mL of a 0.172 M solution?

14. 3. How many moles are there in 205. mL of a 0.172 M solution?

15. 3. How many moles are there in 205. mL of a 0.172 M solution?
0.205 L x moles
1 L

16. 3. How many moles are there in 205. mL of a 0.172 M solution?
0.205 L x moles = moles
1 L

17. 4. How many grams NaCl are there in 250.0 mL of 0.500 M solution?

18. 4. How many grams NaCl are there in 250.0 mL of 0.500 M solution?

19. 4. How many grams NaCl are there in 250.0 mL of 0.500 M solution?
0.250 L x moles
1 L

20. 4. How many grams NaCl are there in 250.0 mL of 0.500 M solution?
0.250 L x moles x g
1 L mole

21. 4. How many grams NaCl are there in 250.0 mL of 0.500 M solution?
0.250 L x moles x g = 7.31 g
1 L mole

22. 5. How many grams of NaCl must be used to prepare a 100. 0 mL. of 0
5. How many grams of NaCl must be used to prepare a mL of M solution.

23. 5. How many grams of NaCl must be used to prepare a 100. 0 mL. of 0
5. How many grams of NaCl must be used to prepare a mL of M solution. L

24. 5. How many grams of NaCl must be used to prepare a 100. 0 mL. of 0
5. How many grams of NaCl must be used to prepare a mL of M solution.
L x moles
1 L

25. 5. How many grams of NaCl must be used to prepare a 100. 0 mL. of 0
5. How many grams of NaCl must be used to prepare a mL of M solution.
L x moles x g
1 L mole

26. 5. How many grams of NaCl must be used to prepare a 100. 0 mL. of 0
5. How many grams of NaCl must be used to prepare a mL of M solution.
L x moles x g = g
1 L mole

27. 6. How many millilitres of a 0. 200 M solution of CoCl2 will
6. How many millilitres of a M solution of CoCl2 will contain 25.0 g?

28. 6. How many millilitres of a 0. 200 M solution of CoCl2 will
6. How many millilitres of a M solution of CoCl2 will contain 25.0 g?
25.0 g

29. 6. How many millilitres of a 0. 200 M solution of CoCl2 will
6. How many millilitres of a M solution of CoCl2 will contain 25.0 g?
25.0 g x mole
129.9 g

30. 6. How many millilitres of a 0. 200 M solution of CoCl2 will
6. How many millilitres of a M solution of CoCl2 will contain 25.0 g?
25.0 g x mole x 1 L
129.9 g mol

31. 6. How many millilitres of a 0. 200 M solution of CoCl2 will
6. How many millilitres of a M solution of CoCl2 will contain 25.0 g?
25.0 g x mole x 1 L x 1000 mL
129.9 g mol L

32. 6. How many millilitres of a 0. 200 M solution of CoCl2 will
6. How many millilitres of a M solution of CoCl2 will contain 25.0 g?
25.0 g x mole x 1 L x 1000 mL = mL
129.9 g mol L

33. 7. Describe how you would prepare 100. 0 mL of a 0. 200 M
7. Describe how you would prepare mL of a M solution of CoCl2.
L x moles x g = g
1 L mole
Weigh 2.60 g of CoCl2
Dissolve in water
Transfer to a 100 mL
volumetric flask and fill to the line