1. Solutions L

2. Solutions Mixture of substances (2+)
State of matter depends on the solvent
Solute: substance that is dissolved
Solvent: substance that does the dissolving

4. Properties of solutions
Homogeneous
Cannot be filtered
Transparent
Can be separated by evaporating the solvent

5. Solubility Soluble – if a substance can be dissolved in the solvent
AKA: Miscible
Insoluble – if a substance can not be dissolved in the solvent
AKA immiscible
Solubility -- How much solvent can be dissolved in a solute at a given temp and pressure

6. Like Dissolves Like! Polar compounds dissolve polar compounds
Water is the universal solvent because of its polarity
Non-polar compounds dissolve non-polar compounds
Benzene can dissolve plastic because both are non-polar

7. Solvation

8. Rate of solubility
Since solubility occurs when molecules collide, increasing the rate of collisions will increase how much quickly the solute dissolves
Stirring
Increasing solute surface area
Increasing temperature
Since the molecules of solvent have to move between the molecules of solute energy is absorbed (endothermic process)

9. Factors that effect solubility
Temperature
Effects solid solubility mainly
Direct relationship with solubility
Pressure
Effects gaseous solubility mainly
Solubility increases as pressure around the solute increases
Soda is bottled at a higher pressure, when opened it begins to effuse out.

10. Solubility curves
Graph assumes a 100g sample of water, if you had 200g just double the values
Different phases dissolve differently
Solids
Higher solubility at higher temp.
(+) slopes
Gases
Higher solubility at lower temps
(-) slopes

11. Solubility curves -think of it like a party
Saturated – on the line
“We’re out of seats, no one can come in till someone leaves.”
Unsaturated – below the line
Coach L’s usual party itinerary
“We got room come on it!”
To calculate how much more can fit in find out how much under the line you are on the Y-axis
Supersaturated – above the line
“I’ve hired a bouncer!”
Excess is precipitate
Solid falls out of solution
To calculate: find how much you are over on the Y-axis and subtract till you get to the line

12. Molarity Concentration – how much stuff do you have in a set space
Molarity -- Concentration of molecules in a solution
Molarity (M) = molsolute
Lsolution
You are usually given grams so you have to convert
You are usually given milliliters so you have to convert

13. 36g HCl X (1mol HCl/36g HCl) = 1mol HCl
Example:
What is the molarity of a solution of 100L of water and 36g of hydrochloric acid
36g HCl X (1mol HCl/36g HCl) = 1mol HCl
1mol HCl/100L H2O = 0.01M HCl

14. Practice
How many grams of CaCl2 would be dissolved in 1.0L of a 0.10M solution of CaCl2?
A Liter of 2M NaOH solution contains how many grams of NaOH?
How many grams of CaCl2 would need to dissolved in 500mL of water to make a 0.20M solution of CaCl2?
11g CaCl2
80g NaOH

15. Dilutions
Since the number of Moles doesn’t change when we change the volume we can find the new concentration with the following formula
M1V1 = M2V2
Ex: what volume, in milliliters of 2.00M calcium chloride (CaCl2) stock solution would you use to make a 0.50L of 0.300M calcium chloride solution?

16. what volume, in milliliters of 2
what volume, in milliliters of 2.00M calcium chloride (CaCl2) stock solution would you use to make a 0.50L of 0.300M calcium chloride solution?
M1V1 = M2V2 M1 = 2.00 M CaCl2 V1 = ? L of 2.00M CaCl2 M2 = 0.300M CaCl2 V2 = 0.50L of 0.3M CaCl2
2M (V1) = 0.3M (0.5L) 2M 2M V1 = L V1 = 75mL

17. Practice
What volume of a 3.0M KI solution would you use to make 0.300L of a 1.25M KI solution?
How many milliliters of a 5.0M H2SO4 stock solution would you need to prepare 100mL of a 0.25M H2SO4
If you dilute 20.0mL of a 3.5M solution to make 100mL of solution, what is the molarity of the dilute solution?
125mL
5.0mL
0.70M

18. Colligative Properties of solutions
Physical properties of solutions that are effected by the number of particles in solutions but NOT by the identity of dissolved particles in solution.
Ionic compounds have a greater effect on colligative properties then covalent compounds
Dissociation factor(df)
How many ions does the compound form?
For non-electrolytic compounds (covalent compounds) the df is always one (1).
For ionic compound the df is the number of ions that form that compound.
Effect:
Vapor pressure
Boiling point
Freezing point

19. Vapor pressure
number of solvent particles exposed to surface, less enter gas phase
Lower vapor pressure

20. Boiling Point
Increases because fewer particles on the surface are contributing to the vapor pressure (takes more energy to raise the vapor pressure)
Dependent on vapor pressure
Kb = difference in temp. of solution
and pure solvent

21. Freezing point When kinetic energy can no longer overcome attraction
Decreases because solute particles get in the way of attractive forces, cause the more energy to need to be lowered for phase change

22. Calculating the effect of solute on freezing points and boiling points
DT = m(df)K Where DT = change in BP or FP (°C) m = molarity or concentration of solution df = dissociation factor K = constant for solvent (given)

23. What is the freezing point of a 0
What is the freezing point of a 0.40m solution of sucrose in ethanol, if ethanol’s normal freezing point is °C?
DT = m(df)K
m = 0.40m
df = 1
K = 1.99 °C/m
DT = 0.40m (1) 1.99°C/m
DT = 0.796°C
New freezing piont = °C – 0.796°C = °C