1. Aim: How do you express concentration of a solution
DO NOW: On a separate sheet of paper, tell me what you did over break. Will be collected in 3 min.
Homework: Do worksheet. Must show work on the bottom of the page. Quiz Wed.

2. Vocabulary
Concentration: a measurement of the amount of solute that is dissolved in a given quantity of solvent
Concentrated solution: a solution containing a large amount of solute
Dilute solution: a solution that contains a small amount of solute

3. Units of Concentration (Table T)
ways to express the amount of solute in solution (concentration)
Mass or Volume percent of solute
Parts per million (ppm)
Molarity

4. Units of Concentration
Percent volume
% volume = volume solute (ml) x 100
volume solution (ml)
Percent mass
% mass = mass solute (g) x 100
mass solution (g)
Solution = solvent + solute

5. Units of Concentration
Example 1:
What is the percent by volume concentration of a
solution in which 75.0 ml of ethanol is diluted to a
volume of ml?

6. Units of Concentration
Example 2:
What volume of acetic acid is present in a bottle containing
350.0 ml of a solution which measures 5.00%
concentration?

7. Units of Concentration
Example 3:
Find the percent by mass in which 41.0 g of NaCl is
dissolved in 331 grams of water.

8. Parts per million (ppm)
ppm solute = (mass solute/total solution mass) x 106

9. ppm Example
Example – In the United States and Canada, drinking water cannot contain more than 5 x 10-4 mg of mercury per 1x 103 mg of sample of solution. In parts per million what would that be?

10. Questions
An aqueous solution has gram of oxygen dissolved in grams of water. Calculate the dissolved oxygen concentration of this solution in parts per million. Your response must include both a correct numerical setup and the calculated result.

11. Molarity (M) M = mols of solute /Liters of solution
Remember moles = given mass x (1 mol/ molar mass)
Formula from Table T
M = mols of solute /Liters of solution
Example – if 40 g of NaOH is dissolved in water to prepare 0.5 L of solution, what is the molarity?

12. M= molarity (conc.)
n= moles of solute
L = liters of solution n M L

13. Question
How many moles of solute are contained in 0.2L of 1M solution?

14. Challenge Question
Find the volume of a 0.75 M solution if it contains 39 grams of potassium hydroxide.

15. Molecules vs. Ionic Compounds in Aqueous solutions
Some molecular compounds dissolve but do not dissociate into ions.
C6H12O6(s) (glucose)  C6H12O6 (aq)
1 mole of sugar gives 1 mole of sugar when dissolved in water

16. Molecules vs. Ionic Compounds in Aqueous solutions
Many ionic compounds dissociate into independent ions when dissolved in water
NaCl (s)  Na+(aq) + Cl-(aq)
1 mole of NaCl solid gives 1 mole of sodium ions and 1 mole of chloride ions when dissolves (total of 2 moles of dissolved particles).
MgCl2 (s)  Mg+2(aq) + 2Cl-(aq)
Total of 3 moles of dissolved particles