Download - Chemistry 102(01) Spring 2012
15-1CHEM 102, Spring 2012 LA TECH
CTH 328 9:30-10:45 am
Instructor: Dr. Upali Siriwardane
e-mail: [email protected]
Office: CTH 311 Phone 257-4941
Office Hours: M,W 8:00-9:00 & 11:00-12:00 am;
Tu,Th,F 8:00 - 10:00 am..
Exams: 9:30-10:45 am, CTH 328.
March 26 , 2012 (Test 1): Chapter 13
April 18 , 2012 (Test 2): Chapter 14 &15
May 14 , 2012 (Test 3): Chapter 16 &18
Optional Comprehensive Final Exam: May 17, 2012 :
Chapters 13, 14, 15, 16, 17, and 18
Chemistry 102(01) Spring 2012
15-2CHEM 102, Spring 2012 LA TECH
Chapter 15. The Chemistry of Solutes and Solutions 15.1 Solubility and Intermolecular Forces 15.2 Enthalpy, Entropy, and Dissolving Solids 15.3 Solubility and Equilibrium 15.4 Temperature and Solubility 15.5 Pressure and Dissolving Gases in Liquids:
Henry's Law15.6 Solution Concentration: Keeping Track of Units15.7 Vapor Pressures, Boiling Points, and Freezing Points
of Solutions15.8 Osmotic Pressure of Solutions15.9 Colloids 15.10 Surfactants15.11 Water: Natural, Clean, and Otherwise
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Solution TerminologySoluteone or more substance(s) dispersed in the solution
Solventmajority substance in a solutionThe solubility of a solid in a solvent is typically given in
g/100 ml.
Types of solutionsMixture of GasesLiquid solutions (L+S,L+L,L+G)Solid solutions (S+S, alloys)Aerosols (L+G)Foam (S+G)
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Miscible vs. Immiscible
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“Likes Dissolve Likes”Materials with similar polarity are soluble in
each other. Dissimilar ones are not.Polar substances with similar forces are likely
to be soluble in each otherNon-polar solutes dissolve in non-polar
solventsstronger solute-solvent attractions favor
solubility, stronger solute-solute or solvent-solvent attractions reduce solubility
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Solubility of Ionic Compounds and Temperature
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Solution Terminology
Miscible - liquids that dissolve in each otherImmiscible - liquids that do not dissolve in each
other due to differences types of interactionsSaturated solutionA solution that contains as much it can hold Unsaturated solutionA solution that contains less than maximum
amountSupersaturated solution A solution that contains more than maximum
amount
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Types of Solutions (Diluted, Saturated, and Supersaturated)
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Supersaturated Solution
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Solute - Solvent Interactions
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The Solution Making Exopthermic Process
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The Solution Making Endothermic Process
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Thermodynamic Factors Affecting Solubility
1. Energy: Enthalpy (DH) Lower energy – DH
2. Order: Entropy (DS) Disorder + DS
Exothermic –DH favors solubility: product favored
Mixing (+DS disorder favors solubility: product favored
Gibbs Free Energy: (Chapter 18)
DGsoln = DHsoln -TDSsoln,
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Types of Solute - Solvent Interactions
All interactions are electrostatic force
~ Coulombic: proprotional to charge and séparation)
1. London Dispersion Forces: (O2 dissolved in Liq. N2)
2. Ion-Ion Interaction: (Ionic liquids in batteries)
3. Ion-Dipole Interaction (hydrated ions Na+
(aq))
4. Dipole-Dipole Interaction (CCl4 in benzene (C6H6)
5. Hydrogen Bonding. (water and éthanol)
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1) What are the main factors affecting a solubility of a solute in a solvent?
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The Solution Making Exopthermic Process
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The Solution Making Endothermic Process
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2) Arrange the following inter-particles forces in liquids and solids in the order of increasing strength:
• ion-ion, • ion-dipole, • hydrogen bond, • dipole-dipole and • London dispersion
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3) Identify the most important type of inter-particle force for each of the following compounds:
a) NaCl(s) or NaCl(l) b) N2(l) or N2(s) c) N2(g) d) Na(s) and Na(l)
e) H2O(l) or H2O(s) f) CH3CH2OH(l) or CH3CH2OH(s)
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4) Which of the above inter-particle force could be named as intermolecular force?
a) NaCl(s) or NaCl(l) b) N2(l) or N2(s) c) N2(g) d) Na(s) and Na(l)
e) H2O(l) or H2O(s) f) CH3CH2OH(l) or CH3CH2OH(s)
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Acetic acid
HC2H3O2
CH3COOH
Hexanol
C6H13OHHexane
C6H14
Propanoic acid
C2H5COOH
“Like Dissolves Like”
Identify Hydrogen Bonding, Polar and Non-polar groups in Covalent Molecules
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5) What types of inter-particle forces solute-solute:DH1, solvent-solvent: DH2, solvent-solute:DH3) are involved when a) CH3CH2OH(l): dissolved in water,H2O:DH1 = ; DH2 = ; DH3= For covalent compounds: DHsoln= DH1+ DH2+ DH3
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Water Dissolving An Ionic Solute
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Solution Process of Ionic Compounds
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Hydration of a Sodium Ion
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Heats of Solution
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4) b) Na2SO4(s) dissolved in water:DH1 = ; DH2 = ; DH3 = Ion-ion inter-particle forces in solids are called
Lattice Energy. ( this is related to DH1)Ion-water inter-particle forces are called Hydration
Energy (this is related to DH2 and DH3) For ionic compounds; DHsoln = DHlattice + DHhyd
Qualitatively speaking which of the above a) or b) would have a more exothermic DHsoln?
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4) What factors make it more exothermic? a) CH3CH2OH in H2O DH1 = ; DH2 = ; DH3=
b) Na2SO4(s) dissolved in water: (DH1 = DHsoln)+ (Hhyd= DH2+ DH3)
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5) Assign the entropy (most +, medium + or least +) for i) S1 –solute: ii) S2-solvent:iii) S3, solution (solvent-solute):
For the following: (Indicate which one is highest, intermediate and lowest order) For
a) CH3CH2OH(l): dissolved in water: S1 = ; S2 = ;S3= Na2SO4(s) dissolved in water: S1 = ; S2 = ;S3 =
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5) Qualitatively speaking which of the above a) or b) would have a more positive DSsoln?
a) CH3CH2OH(l): dissolved in water: S1 = ; S2 = ;S3= b) For Na2SO4(s) dissolved in water: S1 = ; S2 = ;S3 =
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6) Calculate the DHsoln for dissolving CaCl2(s) in water given the Lattice-Energy CaCl2(s) = +2258 kJ/mole), and Hydration energy for CaCl2 = - 2205 kJ/mole (DHsoln = DHlattice + DHhyd =?)
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7) DHsoln value thermodynamically product favored?
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8) For dissolving CaCl2(s) in water, which of the following entropy represent the highest order? Explain.a) S for CaCl2(s): +104.6 J/mole
b) S for H2O(l): +69.91 J/mole
c) S for solution CaCl2(aq): +815 J/mole
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9) Calculate the DSsoln for dissolving CaCl2(s) in water given the entropies of Lattice- CaCl2(s) (S1= +104.6 J/mole), H2O(l)(S2 = +69.91 J/mole); CaCl2(aq)(S3 = +815 J/mole).
DSsoln= Sfinal-Sinitial =S3 - ( S1+ S2)?
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10) Calculate the DSsoln for dissolving CaCl2(s) in water given the entropies of Lattice- CaCl2(s) (S1= +104.6 J/mole), H2O(l)(S2 = +69.91 J/mole); CaCl2(aq)(S3 = +815 J/mole).
DSsoln= Sfinal-Sinitial =S3 - ( S1+ S2)?
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11) DSsoln value thermodynamically product favored?
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12) Based on DGsoln, determine if CaCl2 is soluble at 25C, given,
DGsoln = DHsoln -TDSsoln, and DHsoln and DSsoln calculated above.
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13) Why sand is insoluble in both polar and nonpolar solvents?
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14) How does temperature and pressure affect the solubility of following?
a) NH4NO3(solid) in water with +(positive) DHsoln:
b) CO2 gas in water:
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Solubility of Oxygen in Water
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Henry’s Law
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Henry’s LawSolubility of Gases in SolventsSg = kHPg
where Sg solubilitykH Henry’s Law constantPg partial pressure of gas
Increasing the pressure of a gas above a liquid increases its solubility
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15) Deep sea divers may experience a condition called the "bends" if they do not readjust slowly to the lower pressure at the surface. Using the diagram on pressure dependence solubility of gases on water explain this phenomenon.