1. Review A solution is a homogeneous mixture.
The solvent is the major component of the solution.
The solute is the minor component and active ingredient.
A saturated solution holds the maximum amount of solute that is theoretically possible for a given temperature.

2. Solution Concentration
Is one glass of tea stronger than the other?
What’s true about the “stronger” glass of tea?
How much tea does it have in it compared to the other glass?

3. Concentrated vs. Dilute
How do we know how strong a solution is?
Concentrated – LOTS of solute, little solvent
Dilute – little solute, lots of solvent
Concentrated and dilute are not quantitative
Measurements are needed to get precise data

4. Concentrated solution
Concentrated vs. Dilute
Concentrated solution
Dilute solution
= solute particles

5. Solution Concentration
Concentration – a ratio comparing the amount of solute (the part) to the amount of solution (the whole).
Concentration is expressed by:
% by weight (% w/w)
Mass of solute x 100
Mass of solution
% by volume (% v/v)
Volume of solute x 100
Volume of solution

6. Solution Concentration
parts per million (ppm) or parts per billion (ppb) for very low concentrations
Mass of solute x 1,000,000
Mass of solution
molality (m)
Moles of solute
Mass(kg) of solution
Used for high-concentration solutions or where temperature changes significantly

7. Molarity
Molarity (M) –The most common unit of concentration in chemistry
Unit = moles per liter (mol/L)
Or just M
Formula:
Example: mol/L = M
read as “1.500 Molar”

8. Molarity
What is the Molar concentration of a sol’n if mol KNO3 is dissolved in enough water to make L?

9. Molarity
What is the Molar concentration of a sol’n if 292 grams of NaCl (MM = g/mol) is dissolved in enough water to make 800. mL?
Convert g of NaCl to mol of NaCl
Convert mL to L
Determine Molarity
292gNaCl x 1mol NaCl
58.44g NaCl
= 5.00mol NaCl
800.mL x 1 Liter
1000mL
= 0.800L
Molarity = mol
0.800L
Molarity = 6.25M

10. Molarity
What is the Molar concentration of a sol’n if 10.5 grams of glucose (Molar Mass = g/mol) is dissolved in enough water to make 20.0 mL of sol’n?
Convert g of glucose to mol of glucose.
Convert mL to L.
Determine Molarity
10.5g glucose x 1mol glucose
180.18g glucose
= mol glucose
20.0mL x 1 Liter
1000mL
= L
Molarity = mol
0.0200L
Molarity = 2.92M

11. Boiling Point Elevation & Freezing Point Depression
Concentration affects boiling points and freezing points
The greater the concentration, the greater the effect
Increasing concentration raises the boiling point
Adding salt to boiling pasta cooks it at a hotter temperature
Increasing concentration lowers freezing point
Adding salt/brine to icy roads causes water to freeze at a lower temperature, melting ice and snow
Some solutes have greater affect than others
Ionic compounds dissociate into multiple ions, increasing the number of particles in solution
C12H22O11(s) → C12H22O11(aq)
NaCl(s) → Na+(aq) Cl-(aq)
CaCl2(s) → Ca2+(aq) Cl-(aq)
1 particle
2 particles
3 particles

12. Freezing Point and NaCl Concentration
Normal Freezing Point

13. Percent by Weight % by weight (% w/w)
What is the % w/w of a solution if 3.00 grams of NaCl are dissolved in g of water?
mass of solute = 3.00 g
mass of solution = 3.00 g g = g
(3.00 g / g) x 100% = 15.0% w/w

14. Percent by Volume % by volume (% v/v)
What is the % v/v of a solution if 20.0 mL of alcohol are dissolved in 50.0 mL of solution?
volume of solute = 20.0 mL
volume of solution = 50.0 mL
(20.0 mL / 50.0 mL) x 100% = 40.0%