1. Properties of Solutions

2. Classification of Matter
Solutions are homogeneous mixtures

3. CA Standards Students know the definitions of solute and solvent.
Students know how to calculate the concentration of a solute in terms of grams per liter, molarity, parts per million, and percent composition.

4. Calculations of Solution Concentration

5. Solute Solvent A solute is the dissolved substance in a solution.
Salt in salt water
Sugar in soda drinks
Carbon dioxide in soda drinks
Solvent
A solvent is the dissolving medium in a solution.
Water in salt water
Water in soda

6. Calculations of Solution Concentration
Molarity - the ratio of moles of solute to liters of solution

7. Molarity
Describes the concentration of a solution in moles of solute divided by liters of solution. Masses of solute must first be converted to moles using the molar mass of the solute. This is the most widely used unit for concentration when preparing solutions in chemistry and biology. The units of molarity, mol/L, are usually represented by a scripted capital “M”.

8. example 1.34 M = 3.35 mol 58.5g 1 mol mol 2.50 L 196 g NaCl
How many grams are in 2.50 L of a 1.34 M NaCl soln?
3.35 mol g
1 mol
mol
2.50 L =
1.34 M =
196 g NaCl
1.34 M • 2.50 L = mol
3.35 = mol

9. Practice
Calculate the Molality of sucrose in a solution composed of g of sucrose (C12H22O11) dissolved in L of water.
Correct answer: mol/L

10. Calculations of Solution Concentration: Grams per Liter
Grams per liter is the ratio of mass units of solute to volume (liters) of solution
What is the concentration of a solution in grams/Liter when 80 grams of sodium chloride, NaCl, is dissolved in 2 liters of solution?

11. A Simplifying Assumption
1 ml of water = 1 gram of water
1000 ml of water = 1 liter = 1000 grams
Assume that solutions with water as the solvent have the density of pure water (1 mL = 1 gram)
It’s not true, but it’s close enough 

12. Practice
What is the concentration of a solution in
grams/Liter when 80. grams of sodium chloride,
NaCl, is dissolved in 2.0 liters of solution?
80. g = g/L
2.0 L

13. Calculations of Solution Concentration
Mass percent - the ratio of mass units of solute to mass units of solution, expressed as a percent

14. Heat of Solution
The Heat of Solution is the amount of heat energy absorbed (endothermic) or released (exothermic) when a specific amount of solute dissolves in a solvent.
Substance
Heat of Solution
(kJ/mol)
NaOH
-44.51
NH4NO3
+25.69
KNO3
+34.89
HCl
-74.84

15. “Like Dissolves Like”
Nonpolar solutes dissolve best in nonpolar solvents
Fats
Benzene
Steroids
Hexane
Waxes
Toluene
Polar and ionic solutes dissolve best in polar solvents
Inorganic Salts
Water
Sugars
Small alcohols
Acetic acid

16. Solubility Trends
The solubility of MOST solids increases with temperature.
The rate at which solids dissolve increases with increasing surface area of the solid.
The solubility of gases decreases with increases in temperature.
The solubility of gases increases with the pressure above the solution.

17. Therefore… Solids tend to dissolve best when: Heated Stirred
Ground into small particles
Gases tend to dissolve best when:
The solution is cold
Pressure is high

18. Saturation of Solutions
A solution that contains the maximum amount of solute that may be dissolved under existing conditions is saturated.
A solution that contains less solute than a saturated solution under existing conditions is unsaturated.
A solution that contains more dissolved solute than a saturated solution under the same conditions is supersaturated.

19. Solubility Chart

20. Definition of Electrolytes and Nonelectrolytes
An electrolyte is:
  A substance whose aqueous solution conducts
an electric current.
A nonelectrolyte is:
  A substance whose aqueous solution does not
conduct an electric current.
Try to classify the following substances as
electrolytes or nonelectrolytes…

21. Electrolytes vs. Nonelectrolytes
The ammeter measures the flow of electrons (current)
through the circuit.
If the ammeter measures a current, and the bulb
glows, then the solution conducts.
If the ammeter fails to measure a current, and the
bulb does not glow, the solution is non-conducting.

22. Electrolytes? Pure water Tap water Sugar solution
Sodium chloride solution
Hydrochloric acid solution
Lactic acid solution
Ethyl alcohol solution
Pure sodium chloride

23. Answers to Electrolytes
NONELECTROLYTES:
  Tap water (weak)
  NaCl solution
  HCl solution
  Lactate solution (weak)
  Pure water
  Sugar solution
  Ethanol solution
  Pure NaCl

24. Colligative Properties
Colligative properties are those that depend on the concentration of particles in a solution, not upon the identity of those particles.
Boiling Point Elevation
Freezing Point Depression
Osmotic Pressure

25. Freezing Point Depression
Each mole of solute particles lowers the freezing point of 1 kilogram of water by 1.86 degrees Celsius.
Kf = 1.86 C  kilogram/mol
m = molality of the solution
i = van’t Hoff factor

26. Boiling Point Elevation
Each mole of solute particles raises the boiling point of 1 kilogram of water by 0.51 degrees Celsius.
Kb = 0.51 C  kilogram/mol
m = molality of the solution
i = van’t Hoff factor

27. Freezing Point Depression and Boiling Point Elevation Constants, C/m
Solvent Kf Kb
Acetic acid
3.90
3.07
Benzene
5.12
2.53
Nitrobenzene
8.1
5.24
Phenol
7.27
3.56
Water
1.86
0.512

28. The Van’t Hoff Factor, i
Electrolytes may have two, three or more times the effect on boiling point, freezing point, and osmotic pressure, depending on its dissociation.

29. Dissociation Equations and the Determination of i
NaCl(s) 
Na+(aq) + Cl-(aq)
i = 2
AgNO3(s) 
Ag+(aq) + NO3-(aq)
i = 3
MgCl2(s) 
Mg2+(aq) + 2 Cl-(aq)
i = 3
Na2SO4(s) 
2 Na+(aq) + SO42-(aq)
AlCl3(s) 
Al3+(aq) + 3 Cl-(aq)
i = 4

30. Suspensions and Colloids
Suspensions and colloids are NOT solutions.
Suspensions: The particles are so large that they settle out of the solvent if not constantly stirred.
Colloids: The particles intermediate in size between those of a suspension and those of a solution.

31. Types of Colloids Types of Colloids
Examples
Dispersing
Medium
Dispersed
Substance
Colloid Type
Fog, aerosol sprays
Gas
Liquid
Aerosol
Smoke, airborn germs
Solid
Whipped cream, soap suds
Foam
Milk, mayonnaise
Emulsion
Paint, clays, gelatin
Sol
Marshmallow, Styrofoam
Solid Foam
Butter, cheese
Solid Emulsion
Ruby glass
Solid sol
Examples
Dispersing
Medium
Dispersed
Substance
Colloid Type
Fog, aerosol sprays
Gas
Liquid
Aerosol
Smoke, airborn germs
Solid
Whipped cream, soap suds
Foam
Milk, mayonnaise
Emulsion
Paint, clays, gelatin
Sol
Marshmallow, Styrofoam
Solid Foam
Butter, cheese
Solid Emulsion
Ruby glass
Solid sol

32. The Tyndall Effect
Colloids scatter light, making a beam visible. Solutions do not scatter light.
Which glass contains a colloid?
colloid
solution