1. Solutions
Chapters 13 and 14

2. Solutions are homogeneous mixture
Homogeneous mixture = same composition and properties throughout
Soluble = capable of being dissolved
Solvent = dissolving medium
Water = ‘universal solvent’
Solute = substance being dissolved

3. Examples of solute/solvent
Sodium chloride and water
Solute = sodium chloride Solvent = water
Some water is in the air
Solute = water Solvent = air
14 karat gold is composed of 58% gold and 42% silver
Solute = silver Solvent = gold
Solvent is most abundant

4. Dissociation Separation of ions in an ionic compound
Must have polar solvent (like water) and ionic compound
Hydration = solution process with water as the solvent – water molecules surround the ions and carry them off

6. Ionization
Ions are formed from solute molecules by the action of the solvent
Must have polar solvent (like water) and solute with weak bonds

7. Solubility - “Like dissolves like”
Substances that have similar bonding, polarity, and IMF will dissolve into each other
Toluene is nonpolar
Water is polar
have different characteristics
and will NOT mix – Immiscible

8. More ex. of like dissolves like
Toluene and gasoline are nonpolar
Grease and oils are nonpolar
Therefore, they will mix = Miscible
(Ex Fat soluble and water soluble vitamins)

9. Electrolytes and Nonelectrolytes
Electrolyte = conducts electricity due to mobile charges in solution
Strong and weak – depends on how much they ionize or dissociate
Nonelectrolytes = do not conduct electricity
Neutral solute molecules (sugar dissolved in water)

10. Factors Affecting the Rate of Dissolution
To increase the rate, increase
Surface area
Temperature (except for gases and some solids)
Agitation

11. Solubility
There is a limit to how much solute will dissolve in a certain amount of solvent
Depends on the nature of the solvent, solute, and temperature
Solution Equilibrium – processes of dissolution and
recrystallization occur
at the same rate

12. C. Solubility Solubility
maximum grams of solute that will dissolve in 100 g of solvent at a given temperature
varies with temp
based on a saturated soln

13. Saturated Solution = contains maximum amount of dissolved solute
Unsaturated = contains less solute than a saturated solution
Supersaturated = solution that contains more dissolved solute than saturated
Made by cooling a warm saturated solution, must not be disturbed

14. When does the solution become saturated?
Look at the solubility of the substance = Amount of substance needed to make a saturated solution at a specific temperature

15. Solubility Curve

16. C. Solubility Gases are more soluble at... low temperatures &
Solids are more soluble at...
high temperatures.
Gases are more soluble at...
low temperatures &
high pressures (Henry’s Law).
EX: nitrogen narcosis, the “bends,” soda

17. C. Solubility Solubility Curve
shows the dependence of solubility on temperature

18. Concentration of Solutions
Concentration = amount of solute in a given amt of solvent
Molarity = moles of solute in one liter of solution
M = mol of solute
L of solution
Molality = moles of solute per kilogram of solvent
m = mol of solute
kg of solvent

19. Molarity Examples
You have 0.8 L of a 0.5 M HCl solution. How many moles of HCl does this solution have? (answer 0.4 mol HCl)
What volume of 3.00 M NaCl is needed for a reaction that requires g of NaCl? (answer L)
3.5 L of solution contains 90.0 g of NaCl. What is the solution’ s molarity? (0.441 M)
How many grams of solute are needed to make 2.50 L of a 1.75 M solution of Ba(NO3)2? (1140 g)

20. Molality Examples
What is the molality of a solution composed of 255 g of acetone, (CH3)2CO, dissolved in 200. g of water? (22 m)
How many grams of methanol, CH3OH, are required to prepare a solution in 400. g of water? (3.12 g)
What is the molality of a solution containing 18.2 g HCl and 250. g of water? (1.99 m)

21. Dilutions MdiluteVdilute = MconcentratedVconcentrated Example
How can 100 mL of 0.04 M K2Cr2O7 be prepared from 0.2 M K2Cr2O7?