Solubility

1
Solubility

• A solution is a homogeneous mixture that may be a
  solid, liquid, or gas.
• What factors affect the rate of dissolving for a
  solution?
• Stirring (agitation)
• Temperature
• Surface area of dissolving particles

2
Three types of solutions

• Saturated solution-solution containing the
  maximum amount of solute for a given quantity of
  solvent at a constant temperature and pressure.
• Unsaturated solution-a solution that contains
  less solute than a saturated solution at a given
  temperature and pressure.
• Supersaturated solution-solution containing more
  solute than it can theoretically hold at a given
  temperature.

3
The crystallization of a supersaturated solution
can be initiated if a very small crystal, a seed
crystal of the solute is added.

• Crystallization can also occur if the inside of
  the container is scratched.

4
Solubility
increasing concentration
5
Solubility Table
Solubility vs. Temperature for Solids
140
KI
130
120
NaNO3
110
100
KNO3
90
80
HCl
NH4Cl

• shows the dependence
• of solubility on temperature

70
Solubility (grams of solute/100 g H2O)
60
NH3
KCl
50
40
30
NaCl
KClO3
20
10
SO2
0 10 20 30 40 50 60 70 80 90 100
LeMay Jr, Beall, Robblee, Brower, Chemistry
Connections to Our Changing World , 1996, page
517
6
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 solution

7
Solubility

• Solids are more soluble at...
• high temperatures.

• Gases are more soluble at...
• low temperatures
• high pressures (Henrys Law).
• EX nitrogen narcosis, the bends, soda

8
Solubility
Solids dissolved in liquids Gases
dissolved in liquids
As To , solubility
As To , solubility
9
Solubility ? how much solute dissolves in a
given amt. of solvent at a given temp.
SOLUBILITY CURVE
unsaturated solution could hold more solute
below line saturated solution has just right
amt. of solute on line supersaturated solution
has too much solute dissolved in it above the
line
10
Two types of liquids

• Miscible liquids-two liquids that dissolve in
  each other in all proportions. Examples-water
  and ethanol, water and ethylene glycol.
• Immiscible liquids-liquids that are insoluble in
  one another. Examples-oil and vinegar oil and
  water.

11
Factors Affecting Solubility

• Temperature-for solids, liquids and gases.
• Pressure-gases only.
• For some substances, solubility decreases with
  temperature.

12
Pressure and the gas laws

• Changes in pressure strongly influence the
  solubility of gases, however, have little affect
  on the solubility of solids and liquids. Gas
  solubility increases as the partial pressure of
  the gas above the solution increases. Ex.
  Carbonated beverages produce a fizz.
• Henrys law-states that at a given temperature,
  the solubility of a gas in a liquid is directly
  proportional to the pressure of the gas above the
  liquid.
• Equation for Henrys Law S1/P1 S2/P2

13
Example 1

• The solubility of a gas in water is 0.16g/L at
  104kPa. What is the solubility when the pressure
  of the gas is increased to 288kPa? Assume the
  temperature remains constant.
• S2 ?

14
Molarity

• Concentration of a solution is a measure of the
  amount of solute that is dissolved in a given
  quantity of solvent.
• Dilute solution- a solution containing a small
  amount of solute.
• Concentrated solution- solution containing a
  large amount of solute.
• How do chemists express concentration
  quantitatively? By utilizing molarity.
• Molarity (M)-the number of moles of solute
  dissolved in one liter of solution.
  Molaritymoles of solute/liter of solution.

15
Dilutions

• Diluting a solution reduces the number of moles
  of solute per unit volume, but the total number
  of moles of solute in solution does not change.
• Molarity by dilution M1V1M2V2
• The first M and V are initial Molarity and Volume
  of solution, The second M and V are the molarity
  and volume of the diluted solution.
• See sample Problem 16.4

16
Percent Solutions

• The concentration of a solution in percent can be
  expressed in two ways as the ratio of the volume
  of the solute to the volume of the solution, or
  as the ratio of the mass of solute to the mass of
  the solution.
• by volume (v of V)solute volume/solution
  volume x 100
• by mass (m of m)solute mass/solution mass x
  100

17
Colligative Properties

• Colligative property- a property that depends
  only upon the number of solute particles in the
  solution, and not their identity.
• There are three important colligative properties
  of solutions
• Vapor-pressure lowering
• Boiling point elevation
• Freezing point depression

18
Colligative Properties

• The decrease in a solutions vapor pressure is
  proportional to the number of particles the
  solute makes in solution.
• The magnitude of the freezing-point depression is
  proportional to the number of solute particles
  dissolved in the solvent and does not depend upon
  their identity.
• The magnitude of the boiling-point elevation is
  proportional to the number of solute particles
  dissolved in the solvent.

19
Colligative Properties

• Vapor pressurethe pressure exerted by a vapor
  that is in dynamic equilibrium with its liquid in
  a closed system.
• Freezing-point depressionthe difference in
  temperature between the freezing point of a
  solution and the freezing point of the pure
  solvent.
• Boiling-point elevationthe difference in
  temperature between the boiling-point of a
  solution and the boiling point of the pure
  solvent.

20
Molality and Mole Fraction

• Chemists may express the concentration of a
  solution utilizing molality and mole fraction.
• Molalitymoles of solute/kg of solvent
• 1kg1000g See sample problem 16.6
• Mole fraction-the ratio of the moles of solute to
  the total number of moles of solvent and solute.
• nAmoles of solute A nBmoles of solvent B
• XAmole fraction of solute A, XBmole fraction of
  solvent B.
• The magnitude of the freezing point depression
  ?Tf and boiling point elevation ?Tb of a solution
  are directly proportional to the molal
  concentration m, when the solute is molecular,
  not ionic.

21
Solubility
Classify as unsaturated, saturated, or
supersaturated.

per 100 g H2O
80 g NaNO3 _at_ 30oC unsaturated 45 g KCl _at_
60oC saturated 50 g NH3 _at_ 10oC unsaturated 7
0 g NH4Cl _at_ 70oC supersaturated
Per 500 g H2O, 120 g KNO3 _at_ 40oC
saturation point _at_ 40oC for 100 g H2O 66 g KNO3
So sat. pt. _at_ 40oC for 500 g H2O 5 x 66 g 330
g
120 g lt 330 g unsaturated
22
Describe each situation below.
(A) Per 100 g H2O, 100 g Unsaturated all
solute NaNO3 _at_ 50oC. dissolves clear
solution.
(B) Cool solution (A) very
Supersaturated extra slowly to 10oC.
solute remains in solution still
clear.
(C) Quench solution (A) in Saturated extra
solute an ice bath to 10oC. (20 g) cant
remain in solution, becomes visible.
23
Hotpack / Coldpack
24
Hot and Cold Packs Article
Article "Hot and Cold Packs" 
ChemMatters Feb. 1987 Questions
Article "Hot and Cold Packs"
ChemMatters Feb. 1987 Questions
Keys
25
Solubility of Sodium Acetate
150
Saturated
Supersaturated solution
Video Clip
100
Solubility(g/100 g H2O)
Unsaturated solution
50
0
A single crystal of sodium acetate, NaC2H3O2, is
dropped into a supersatureated solution
The small crystal causes extensive crystallization
, and eventually
25
50
75
100
the solute forms a solid mass of NaC2H3O2.
Temperature (oC)
Charles H.Corwin, Introductory Chemistry 2005,
page 378
26
Solubility Equilibrium
27
Vitamins

• Multi Vitamin
• Provides many essential vitamins
• Expensive urine
• Water Soluble
• Vitamin C
• Must be replenished regularly
• Fat Soluble
• Can overdose
• Vitamin A
• Can be ingested periodically, stored in body fat

28
Steroids
Bob Hazelton Article - Steroids
Bob Hazelton Article - Steroids
Keys
29
Reverse Osmosis
30
Reverse Osmosis
Kelter, Carr, Scott, Chemistry A Wolrd of Choices
1999, page 267
31
Net Solvent Flow
Net flow of solvent
Dilute solution
Net flow of solvent
Concentrated solution
Solute particle
Solvent particle
Ralph A. Burns, Fundamentals of Chemistry 1999,
page 430
32
Gas, Liquid, and Solid
Zumdahl, Zumdahl, DeCoste, World of Chemistry
2002, page 441
33
Classes of Reactions
Chemical reactions
Precipitation reactions
Acid-Base Reactions
Oxidation-Reduction Reactions
Combustion Reactions
Zumdahl, Zumdahl, DeCoste, World of Chemistry
2002, page 240
34
Summary of Classes of Reactions
Chemical reactions
Precipitation reactions
Acid-Base Reactions
Oxidation-Reduction Reactions
Combustion Reactions
Decomposition reactions (Products are
elements.)
Synthesis reactions (Reactants are elements.)
Zumdahl, Zumdahl, DeCoste, World of Chemistry
2002, page 242
35
Dissociate in Water
36
Hydrogen Bonding

• Intermolecular forces
• of attraction between
• molecules
• Bonds exist within
• molecules

Zumdahl, Zumdahl, DeCoste, World of Chemistry
2002, page 442
37
K
NO3-
K
K
NO3-
NO3-
K
NO3-
NO3-
K
NO3-
K
AgCl precipitate
AgCl precipitate
38
Dissolving of NaCl
Timberlake, Chemistry 7th Edition, page 287
39
Solutions

• Unit 10

40
Liquid Nitrogen Demonstrations
        Liquid Nitrogen
        Liquid Nitrogen
Keys
41
Titration of Vitamin C with Iodine
Titration of Vitamin C with Iodine
Titration of Vitamin C with Iodine
Keys
42
Definitions
Solute - KMnO4
Solvent - H2O
43
Solvation

• Dissociation
• separation of an ionic solid into aqueous ions

NaCl(s) ? Na(aq) Cl(aq)
44
Solvation

• Ionization
• breaking apart of some polar molecules into
  aqueous ions

HNO3(aq) H2O(l) ? H3O(aq) NO3(aq)
45
Solvation

• Molecular Solvation
• molecules stay intact

C6H12O6(s) ? C6H12O6(aq)
46
Resources - Solutions
Objectives
Objectives - kinetics / equilibrium
Worksheet - vocabulary
Worksheet - review colligative properties
Demonstration - tyndall effect
Worksheet - molarity and stoichiometry
Worksheet - textbook problems
Article - soap (questions)
Activity - serial dilution activity
Lab - soap
Worksheet - dilution of solutions
Article - lava lamp
Worksheet - molarity of solutions
Article - hot / cold pack
Article - don't sweat the small stuff
Lab - salol (freezing point depression)
Worksheet - colligative properties
Lab - titration of vit C with I2
Article - steroids (Bob Hazelton)
Worksheet - electrolytes and colligative
properties
Outline (general)
47
Resources - Solutions
Objectives
Objectives - kinetics / equilibrium
Worksheet - vocabulary
Worksheet - review colligative properties
Demonstration - tyndall effect
Worksheet - molarity and stoichiometry
Worksheet - textbook problems
Article - soap (questions)
Activity - serial dilution activity
Lab - soap
Worksheet - dilution of solutions
Article - lava lamp
Worksheet - molarity of solutions
Article - hot / cold pack
Article - don't sweat the small stuff
Lab - salol (freezing point depression)
Worksheet - colligative properties
Lab - titration of vit C with I2
Article - steroids (Bob Hazelton)
Worksheet - electrolytes and colligative
properties
Lab - ions in solution
Outline (general)