1. A simple matter of concentration
Molarity
A simple matter of concentration

2. Molar Conversions…so far
So far, we have seen that we can use molar masses to convert between ______________ and Avogadro's number to convert between ____________________.

3. Molar Conversions
We also have been working on stoichiometry problems where we are describing and using _______ reagents which we can measure out a mass of in ___________.

4. Stoichiometry…so far
Using stoich, we know that we can convert from grams of any reactant or product into grams of any other reactant or product using the ______ _________ from a balanced chemical equation.
- But we had to be in ________ first!

5. Molarity: A New Stoich Conversion
But what if you are using a reagent that isn’t a solid you can mass out back in lab? What if you are working with a _______________?
Since stoichiometry requires that we get to the units of ___________, we need to be able to figure out how many moles of dissolved substance is in a _____________.
Described as a solution’s ____________ or _______.

6. Solutions Refresher
Solutions are homogenous mixtures (look uniform) of a __________ and ____________. Solute: Solvent:

7. Types of Solutions
Solute/Solvent solution mixtures can be formed by combining ____________________
Gas/Gas:
Gas/Liquid:
Liquid/Liquid:
Solid/Liquid:
Solid/Solid:
For the purposes of this unit, we will mostly focus on _____________ solutions (salt/water)

8. Molarity
Molarity is a measure of the concentration of ________ in a total volume of _________.
***Note that we are describing the volume of the entire solution, not of solvent!***
Specifically, molarity describes the ______ of solute per _______ of solution.
Units =

9. Molarity: Moles per Liter of Solution
So, what we are really measuring when we describe a solution’s concentration is the ____________ of molecules present, not the mass of molecules present.
Example: If our room represents a solution with 2700 lbs of people (or 25 people) in it…
and we have the half mass leave…
versus having half of the people leave…

10. Molarity and Moles
Molarity is a measure of the moles of solute per liter of solution.
Units = mol/L or M
So, if molarity has a mol/L _______ for units it probably isn’t surprising we will use it as a ___________________...later. For now, let’s practice calculating molarity values.

11. Calculating Molarity
Example: A 500. mL solution containing 3.44 grams of KNO3 would have a molarity of M.
*Notice that 2 common lab units, grams and millileters, must be converted to moles and liters!!*

12. Try It!
Determine the molarity of a 1200 mL solution that has 13.0 grams of aluminum chloride dissolved in it.

13. Tricks for Calculating Molarity
1) Make sure you are in ________ and ________ before attempting calculations.
Perform any necessary conversions prior to calculating molarity
mL -> L grams -> mol
2) Use the _______________
Cover up the value you are
solving for. (n = mol)

14. Try It! Complete questions 1-10 on the Molarity Introduction handout.
Check your answers with your neighbor.
Go rock them and let me know if you have any questions!