Chemistry 102(01) Spring 2013
Instructor: Dr. Upali Siriwardane
e-mail: upali@coes.latech.edu
Office: CTH 311
Phone 257-4941
Office Hours: M,W 8:00-9:00 & 11:00-12:00 am;
Tu,Th,F 9:30 - 11:30 am.
Test Dates:
September 27, 2013 (Test 1): Chapter 12 & 13
April 24,
2013 (Test 2): Chapter 14 & 15
May13, 2013 (Test 3) Chapter 16 & 17
May 15, 2012 (Make-up test) comprehensive: Chapters
12-17 9:30-10:45:15 AM, CTH 328
CHEM 102, Spring 2013 LA TECH
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Text Book & Resources
REQUIRED :
Textbook: Principles of Chemistry: A Molecular Approach,
2nd Edition-Nivaldo J. Tro - Pearson Prentice Hall and also
purchase the Mastering Chemistry
Group Homework, Slides and Exam review guides and
sample exam questions are available online:
http://moodle.latech.edu/ and follow the course information
links.
OPTIONAL :
Study Guide: Chemistry: A Molecular Approach, 2nd EditionNivaldo J. Tro 2nd Edition
Student Solutions Manual: Chemistry: A Molecular
Approach, 2nd Edition-Nivaldo J. Tro 2nd
CHEM 102, Spring 2013 LA TECH
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Chapter 12. Solutions
12.1 Thirsty Solutions:
12.2 Types of Solutions and Solubility
12.3 Energetics of Solution Formation
12.4 Solubility Equilibrium and Factors Affecting solution
Formation
12.5 Expressing Solution Concentration
12.6 Colligative Properties: Vapor Pressure, Freezing Point,
Boiling Point, Osmatic Pressure
12.7 Colligative properties of Strong Electrolytes
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Solution Terminology
solute
one or more substance(s) dispersed in the solution
solvent
majority substance in a solution
The solubility of a solid in a solvent is typically given in
g/100 ml.
Types of solutions
Mixture of Gases
Liquid 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 other
Non-polar solutes dissolve in non-polar
solvents
stronger solute-solvent attractions favor
solubility, stronger solute-solute or solventsolvent 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 other
Immiscible - liquids that do not dissolve in each
other due to differences types of interactions
Saturated solution
A solution that contains as much it can hold
Unsaturated solution
A solution that contains less than maximum
amount
Supersaturated 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 separation)
1.
2.
3.
4.
5.
London Dispersion Forces: (O2 dissolved in Liq. N2)
Ion-Ion Interaction: (Ionic liquids in batteries)
Ion-Dipole Interaction (hydrated ions Na+(aq))
Dipole-Dipole Interaction (CCl4 in benzene (C6H6)
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)
CHEM 102, Spring 2013 LA TECH
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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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Identify Hydrogen Bonding, Polar and
Non-polar groups in Covalent
Molecules
Acetic acid
HC2H3O2
CH3COOH
Hexanol
C6H13OH
Hexane
C6H14
Propanoic acid
C2H5COOH
“Like Dissolves Like”
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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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5) 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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6) 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 =
CHEM 102, Spring 2013 LA TECH
;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 =
CHEM 102, Spring 2013 LA TECH
; S2 =
;S3 =
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7) Why sand is insoluble in both polar and nonpolar
solvents?
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8) 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 Law
Solubility of Gases in Solvents
Sg = kHPg
where
Sg  solubility
kH  Henry’s Law constant
Pg  partial pressure of gas
Increasing the pressure of a
gas above a liquid increases
its solubility
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9) 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.
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Solution Concentration Units
a) Molarity (M)
b) Molality (m)
c) Mole fraction (Ca)
d) Mass percent (% weight)
e) Volume percent (% volume)
f) "Proof"
g) ppm and ppb
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Molarity
The number of moles of solute per liter of
solution.
molarity  M
moles of solute
M=
liter of solution
units  molar = moles/liter = M
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Molarity Calculation
An aqueous solution 58.5 g of NaCl and 2206g
water has a density of 1.108 g/cm3. Calculate the
Molarity of the solution.
58.5 g  1 mole
Solution volume  58.5 g + 2206 g in L
2264.5 g solution
1 cm3 solution
1 L solution
1.108 g solution
1000 cm3 solution
= 2.044 L solution
1.00 mole NaCl
Molarity of NaCl solution = ------------------------- = 0.489
M
2.044 L solution
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Molality
number of moles of solute particles (ions or
molecules) per kilogram of solvent
#moles solute
m=
#kilograms of solvent
Calculate the molality of C2H5OH in water
solution which is prepared by mixing 75.0 mL
of C2H5OH and 125 g of H2O at 20oC. The
density of C2H5OH is 0.789 g/mL.
CHEM 102, Spring 2013 LA TECH
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Molarity Calculation
75.0 mL C2H5OH
0.789 g C2H5OH
1 mole C2H5OH
1 mL
46.08 g C2H5OH
= 1.284 C2H5OH
125 g of H2O = 0.125 kg H2O
1.284 mole C2H5OH
Molality(m) = ------------------------ = 10.27 m
0.125 kg H2O
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Mole Fraction
Xi =
#moles of component i
total number of moles
Calculate the mole fraction of benzene in a
benzene(C6H6)-chloroform(CHCl3) solution
which contains 60 g of benzene and 30 g of
chloroform.
M.W. = 78.12 (C6H6)
M.W. = 119.37 (CHCl3)
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Mole Fraction Calculation
moles of a
na
Mola Fraction(ca) = ------------------- = -------------moles of na + moles nb na + nb
a = C6H6
b = CHCl3
nC6H6
Mola Fraction(ca) = -----------------nC6H6 + nCHCl3
m.w (C6H6) = 78.12 g/mole m.w (CHCl3) = 119.37 g/mole
60/78.12 = 0.768 mole C6H6
30/119.37 = 0.251 mole CHCl3
ca(C6H6) = 0.768/ 0.786+ 0.251
=0.754
Ca(CHCl3) = 0.0.251/ 0.786+ 0.251 = 0.246
1.000
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Weight Percent
wt % =
#g of solute
#g of solution
 102
Volume Percent
Vol % =
#L of solute
#L of solution
 102
Proof
proof = Vol % x 2
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Problem
What is the mole fraction of ethanol,
C2H5OH, in ethanol solution that is
40.%(w/w) ethanol, C2H5OH, by mass?
a. 0.40 b. 0.46 c. 0.21 d. 0.54
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Parts per Million
#g of solute
#mg of solute
 106 =
ppm =
#g of solution
#kg of solution
#mL solute
ppm =
#L of solution
Parts per Billion
#g of solute
ppb =
#g of solution
CHEM 102, Spring 2013 LA TECH
 109 =
#micro-g of solute
#kg of solution
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ppm and ppb conversions
1 ppm = (1g/ 1x 106g) 1x 106
= (1/1000 g) x 1x 106
1x 106 / 1000g
= mg/ 1x 103 g
= mg/ L
1 ppb = (1g/ 1x 109g) 1x 109
= (1/1000000 g)
1x 109/1000000g
= mg/ 1x 103 g
= mg/ L
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Problem
A solution of hydrogen peroxide is 30.0%
H2O2 by mass and has a density of 1.11
g/cm3. The MOLARITY of the solution is:
a) 7.94 M b) 8.82 M
e) none of these
c) 9.79 M d) 0.980
M.W. = 34.02 (H2O2)
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10) Define following solution concentration units:
a) Molarity (M)
b) Molality (m)
c) Mole fraction (Ca) weight)
d) Mass percent (%
e) Volume percent (% volume)
f) "Proof"
g) ppm and ppb
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Comparison of Concentration
Terms
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11) Compare the advantages and disadvantages of
these solution concentration parameters.
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12) Determine the number of moles of solute present
in 416 mL of 3.75 M HBr solution.
(Atomic weights: Br = 79.9, H = 1.008).
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13) Determine the mass (g) of solute required to form
25 mL of a 0.1881 M H2O2 solution. (Atomic weight O = 16.00, H = 1.008).
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14) A concentrated solution of AgNO3 is 21.9% by
weight and the density is 1.220 g/cm3. How many
grams of the solution are required to prepare 150.0
mL of a 0.200M solution?
(Atomic weights: Ag = 107.87, N = 14.01, O = 16.00).
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15) A solution of carbon tetrachloride, CCl4, in
benzene (C6H6) is 0.010 m. What mass (g) of CCl4 is
in 50.0 g of benzene?
(Atomic weights: C = 12.01, H = 1.008, Cl = 35.45).
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