1. Unit 3, Lesson 10: Molarity

2. Concentration
The concentration of a substance is the amount of the substance that exists in a given volume of a solution.
A concentrated solution has a relatively high concentration. (There is a large amount of solute.)
A dilute solution has a relatively low concentration. (There is very little solute.)

3. Molarity
Molarity is a measurement of concentration, equal to the number of moles of a substance contained in 1 L of solution (not 1 L of solvent!).
It is measured in mol/L, written as “M”, which stands for molar.
Square brackets around a chemical formula (e.g. [NaCl]) refer to the concentration of that chemical.

4. Brain Break!

5. Molarity Example
If 2.0 L of solution contains 5.0 mol of NaCl, what is [NaCl]?
10 min

6. Making Solutions Read “Making Up Solutions” on pg. 97, and do #56-58.
Next class, you will prepare a mL solution of 0.10 M NaCl. For homework, find the mass of NaCl needed to make this solution!
20 min