Solubility A solution is a homogeneous mixture that may be a solid, liquid, or gas. What factors...
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Transcript of Solubility A solution is a homogeneous mixture that may be a solid, liquid, or gas. What factors...
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
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.
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.
Solubility
SATURATED SOLUTION
no more solute dissolves
UNSATURATED SOLUTIONmore solute
dissolves
SUPERSATURATED SOLUTION
becomes unstable, crystals form
increasing concentration
Solubility Table
LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 517
0 10 20 30 40 50 60 70 80 90 100
Solubility vs. Temperature for Solids
Sol
ubili
ty (
gram
s of
sol
ute/
100
g H
2O)
KI
KCl
20
10
30
40
50
60
70
80
90
110
120
130
140
100
NaNO3
KNO3
HCl NH4Cl
NH3
NaCl KClO3
SO2
shows the dependence
of solubility on temperature
gases
solids
Solubility
SolubilitySolubility
maximum grams of solute that will dissolve in 100 g of solvent at a given temperature
varies with temp
based on a saturated solution
SolubilitySolubility
Solids are more soluble at...Solids are more soluble at...• high temperatures.
Gases are more soluble at...Gases are more soluble at...• low temperatures &• high pressures
(Henry’s Law).• EX: nitrogen narcosis,
the “bends,” soda
Solubility
To
Sol.
To
Sol.
Solids dissolved in liquids Gases dissolved in liquids
As To , solubility As To , solubility
Temp. (oC)
Solubility(g/100 g H2O)
KNO3 (s)
KCl (s)
HCl (g)
SOLUBILITYCURVE
Solubility how much solute dissolves in a given amt.
of solvent at a given temp.
unsaturated: solution could hold more solute; belowbelow line
saturated: solution has “just right” amt. of solute; onon line
supersaturated: solution has “too much” solute dissolved in it;
above the line
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.
Factors Affecting Solubility:
• Temperature-for solids, liquids and gases.• Pressure-gases only.• For some substances, solubility decreases with
temperature.
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.
• Henry’s 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 Henry’s Law: S1/P1 = S2/P2
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 =?
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. Molarity=moles of solute/liter of solution.
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: M1V1=M2V2
• 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
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
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
Colligative Properties…
• The decrease in a solution’s 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.
Colligative Properties…
• Vapor pressure=the pressure exerted by a vapor that is in dynamic equilibrium with its liquid in a closed system.
• Freezing-point depression=the difference in temperature between the freezing point of a solution and the freezing point of the pure solvent.
• Boiling-point elevation=the difference in temperature between the boiling-point of a solution and the boiling point of the pure solvent.
Molality and Mole Fraction:• Chemists may express the concentration of a solution utilizing
molality and mole fraction.• Molality=moles of solute/kg of solvent• 1kg=1000g See sample problem 16.6• Mole fraction-the ratio of the moles of solute to the total
number of moles of solvent and solute.• nA=moles of solute A nB=moles of solvent B• XA=mole fraction of solute A, XB=mole 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.
Solubility
per100 gH2O
Classify as unsaturated, saturated, or supersaturated.
80 g NaNO3 @ 30oC unsaturated
45 g KCl @ 60oC saturated
50 g NH3 @ 10oC unsaturated
70 g NH4Cl @ 70oC supersaturated
So sat. pt. @ 40oC for 500 g H2O = 5 x 66 g = 330 g
120 g < 330 g unsaturated
saturation point @ 40oC for 100 g H2O = 66 g KNO3
Per 500 g H2O, 120 g KNO3 @ 40oC
(A) Per 100 g H2O, 100 g Unsaturated; all
soluteNaNO3 @ 50oC. dissolves; clear
solution.
(B) Cool solution (A) very Supersaturated; extraslowly to 10oC. solute remains in solution;
still clear.
Describe each situation below.
(C) Quench solution (A) in Saturated; extra solute an ice bath to 10oC. (20 g) can’t remain in
solution, becomes visible.
Hotpack / Coldpack
Hot and Cold Packs Article
http://www.unit5.org/christjs/tempT27dFields-Jeff/Solutions1.htm
KeysKeysKeysKeys
Article "Hot and Cold Packs"
ChemMatters Feb. 1987 Questions
Article "Hot and Cold Packs"
ChemMatters Feb. 1987 Questions
Solubility of Sodium Acetate
Temperature (oC)
025 50 75 100
Sol
ubili
ty(g
/100
g H
2O)
50
100
150Supersaturated
solution
Unsaturated solution
Saturated
Video Clip
Charles H.Corwin, Introductory Chemistry 2005, page 378
A single crystal of sodium acetate, NaC2H3O2, is dropped into a
supersatureated solution
The small crystal causes extensivecrystallization, and eventually
the solute forms a solid mass of NaC2H3O2.
Solubility Equilibrium
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
Steroids
http://www.unit5.org/christjs/tempT27dFields-Jeff/Solutions1.htm
KeysKeysKeysKeys
Bob Hazelton Article - Steroids
Bob Hazelton Article - Steroids
Reverse Osmosis
Reverse Osmosis
Kelter, Carr, Scott, Chemistry A Wolrd of Choices 1999, page 267
Net flow of solvent
Net Solvent Flow
Dilutesolution Concentrated
solution
Solute particle Solvent particle
Ralph A. Burns, Fundamentals of Chemistry 1999, page 430
semipermeable membrane
Net flow of solvent
Gas, Liquid, and Solid
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 441
Classes of Reactions
Chemical reactionsChemical reactions
Precipitation reactions
Precipitation reactions
Acid-BaseReactionsAcid-BaseReactions
Oxidation-ReductionReactions
Oxidation-ReductionReactions
Combustion Reactions
Combustion Reactions
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 240
Summary of Classes of Reactions
Chemical reactionsChemical reactions
Precipitation reactions
Precipitation reactions
Acid-BaseReactionsAcid-BaseReactions
Oxidation-ReductionReactions
Oxidation-ReductionReactions
Combustion Reactions
Combustion Reactions
Decomposition reactions
(Products are elements.)
Decomposition reactions
(Products are elements.)
Synthesis reactions
(Reactants are elements.)
Synthesis reactions
(Reactants are elements.)
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 242
Dissociate in Water
Hydrogen Bonding
• Intermolecular forcesof attraction between
molecules
• Bonds exist withinmolecules
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 442
K+
K+
K+NO3-
NO3-
NO3-
AgCl precipitate
K+
K+
K+NO3-
NO3-
NO3-
AgCl precipitate
Dissolving of NaCl
Timberlake, Chemistry 7th Edition, page 287
Solutions
Unit 10
Liquid Nitrogen Demonstrations
http://www.unit5.org/christjs/tempT27dFields-Jeff/Solutions1.htm
KeysKeysKeysKeys
Liquid Nitrogen
Liquid Nitrogen
Titration of Vitamin C with Iodine
http://www.unit5.org/christjs/tempT27dFields-Jeff/Solutions1.htm
KeysKeysKeysKeys
Titration of Vitamin C with Iodine
Titration of Vitamin C with Iodine
DefinitionsDefinitions
Solute Solute - KMnO4 Solvent Solvent - H2O
Resources - Solutions
ObjectivesObjectives - kinetics / equilibrium - kinetics / equilibrium
WorksheeWorksheet - vocabulary - vocabulary
Demonstration - tyndall effectDemonstration - tyndall effect
Worksheet - textbook problemsWorksheet - textbook problems
Activity - serial dilution activityActivity - serial dilution activity
Worksheet - dilution of solutionsWorksheet - dilution of solutions
Worksheet - molarity of solutionsWorksheet - molarity of solutions
Article - don't sweat the small stuffArticle - don't sweat the small stuff
Worksheet - colligative propertiesWorksheet - colligative properties
Outline (general)(general)
Worksheet - review colligative propertiesWorksheet - review colligative properties
Worksheet - molarity and stoichiometryWorksheet - molarity and stoichiometry
Article - soap (questions) Article - soap (questions)
Lab - soapLab - soap
Article - lava lampArticle - lava lamp
Article - hot / cold packArticle - hot / cold pack
Lab - salol (freezing point depression)Lab - salol (freezing point depression)
Lab - titration of vit C with ILab - titration of vit C with I22
Worksheet - electrolytes and colligative properties Worksheet - electrolytes and colligative properties Article - steroids (Bob Hazelton)Article - steroids (Bob Hazelton)
Resources - Solutions
ObjectivesObjectives - kinetics / equilibrium - kinetics / equilibrium
Worksheet - vocabulary - vocabulary
Demonstration - tyndall effectDemonstration - tyndall effect
Worksheet - textbook problemsWorksheet - textbook problems
Activity - serial dilution activityActivity - serial dilution activity
Worksheet - dilution of solutions - dilution of solutions
Worksheet - molarity of solutions - molarity of solutions
Article - don't sweat the small stuff - don't sweat the small stuff
Worksheet - colligative properties- colligative properties
Outline (general)(general)
Worksheet - review colligative propertiesWorksheet - review colligative properties
Worksheet - molarity and stoichiometryWorksheet - molarity and stoichiometry
Article - soap (questions) Article - soap (questions)
Lab - soapLab - soap
Article - lava lampArticle - lava lamp
Article - hot / cold packArticle - hot / cold pack
Lab - salol (freezing point depression)Lab - salol (freezing point depression)
Lab - titration of vit C with ILab - titration of vit C with I22
Worksheet - electrolytes and colligative properties Worksheet - electrolytes and colligative properties Article - steroids (Bob Hazelton)Article - steroids (Bob Hazelton)
Lab - ions in solutionLab - ions in solution