12-1CHEM 102, Spring 2013 LA TECH
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 9:30 - 11:30 am.
Test Dates:
Chemistry 102(01) Spring 2013
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
12-2CHEM 102, Spring 2013 LA TECH
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 Edition-Nivaldo J. Tro 2nd Edition
Student Solutions Manual: Chemistry: A Molecular Approach, 2nd Edition-Nivaldo J. Tro 2nd
Text Book & Resources
12-3CHEM 102, Spring 2013 LA TECH
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
12-4CHEM 102, Spring 2013 LA TECH
Solution Terminology
soluteone or more substance(s) dispersed in the solutionsolventmajority 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)
12-5CHEM 102, Spring 2013 LA TECH
Miscible vs. Immiscible
12-6CHEM 102, Spring 2013 LA TECH
“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 solvent-solvent attractions reduce solubility
12-7CHEM 102, Spring 2013 LA TECH
Solubility of Ionic Compounds and Temperature
12-8CHEM 102, Spring 2013 LA TECH
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
12-9CHEM 102, Spring 2013 LA TECH
Types of Solutions (Diluted, Saturated, and Supersaturated)
12-10CHEM 102, Spring 2013 LA TECH
Supersaturated Solution
12-11CHEM 102, Spring 2013 LA TECH
Solute - Solvent Interactions
12-12CHEM 102, Spring 2013 LA TECH
The Solution Making Exopthermic Process
12-13CHEM 102, Spring 2013 LA TECH
The Solution Making Endothermic Process
12-14CHEM 102, Spring 2013 LA TECH
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,
12-15CHEM 102, Spring 2013 LA TECH
Types of Solute - Solvent Interactions
All interactions are electrostatic force
~ Coulombic: proprotional to charge and separation)
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)
12-16CHEM 102, Spring 2013 LA TECH
1) What are the main factors affecting a solubility of a solute in a solvent?
12-17CHEM 102, Spring 2013 LA TECH
The Solution Making Exopthermic Process
12-18CHEM 102, Spring 2013 LA TECH
The Solution Making Endothermic Process
12-19CHEM 102, Spring 2013 LA TECH
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
12-20CHEM 102, Spring 2013 LA TECH
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)
12-21CHEM 102, Spring 2013 LA TECH
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)
12-22CHEM 102, Spring 2013 LA TECH
Acetic acid
HC2H3O2
CH3COOH
Hexanol
C6H13OHHexane
C6H14
Propanoic acid
C2H5COOH
“Like Dissolves Like”
Identify Hydrogen Bonding, Polar and Non-polar groups in Covalent Molecules
12-23CHEM 102, Spring 2013 LA TECH
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
12-24CHEM 102, Spring 2013 LA TECH
Water Dissolving An Ionic Solute
12-25CHEM 102, Spring 2013 LA TECH
Solution Process of Ionic Compounds
12-26CHEM 102, Spring 2013 LA TECH
Hydration of a Sodium Ion
12-27CHEM 102, Spring 2013 LA TECH
Heats of Solution
12-28CHEM 102, Spring 2013 LA TECH
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?
12-29CHEM 102, Spring 2013 LA TECH
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 = ;S3 =
12-30CHEM 102, Spring 2013 LA TECH
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 =
12-31CHEM 102, Spring 2013 LA TECH
7) Why sand is insoluble in both polar and nonpolar solvents?
12-32CHEM 102, Spring 2013 LA TECH
8) How does temperature and pressure affect the solubility of following?
a) NH4NO3(solid) in water with +(positive) DHsoln:
b) CO2 gas in water:
12-33CHEM 102, Spring 2013 LA TECH
Solubility of Oxygen in Water
12-34CHEM 102, Spring 2013 LA TECH
Henry’s Law
12-35CHEM 102, Spring 2013 LA TECH
Henry’s LawSolubility of Gases in SolventsSg = 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
12-36CHEM 102, Spring 2013 LA TECH
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.
12-37CHEM 102, Spring 2013 LA TECH
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
12-38CHEM 102, Spring 2013 LA TECH
Molarity
The number of moles of solute per liter of solution.
molarity M
moles of soluteM =
liter of solution
units molar = moles/liter = M
12-39CHEM 102, Spring 2013 LA TECH
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
1.00 mole NaCl Molarity of NaCl solution = ------------------------- = 0.489
M 2.044 L solution
2264.5 g solution 1 cm3 solution 1 L solution= 2.044 L solution
1.108 g solution 1000 cm3 solution
Molarity Calculation
12-40CHEM 102, Spring 2013 LA TECH
Molalitynumber 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.
12-41CHEM 102, Spring 2013 LA TECH
125 g of H2O = 0.125 kg H2O
1.284 mole C2H5OH
Molality(m) = ------------------------ = 10.27 m
0.125 kg H2O
75.0 mL C2H5OH 0.789 g C2H5OH 1 mole C2H5OH= 1.284 C2H5OH
1 mL 46.08 g C2H5OH
Molarity Calculation
12-42CHEM 102, Spring 2013 LA TECH
Mole Fraction#moles of component i
Xi = 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)
12-43CHEM 102, Spring 2013 LA TECH
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
Mole Fraction Calculation
12-44CHEM 102, Spring 2013 LA TECH
Weight Percent #g of solute
wt % = 102
#g of solution
Volume Percent
#L of solute
Vol % = 102
#L of solution
Proof
proof = Vol % x 2
12-45CHEM 102, Spring 2013 LA TECH
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
12-46CHEM 102, Spring 2013 LA TECH
Parts per Million
#g of solute #mg of solute
ppm = 106 =
#g of solution #kg of solution
#mL solute ppm =
#L of solution
Parts per Billion
#g of solute #micro-g of solute
ppb = 109
=
#g of solution #kg of solution
12-47CHEM 102, Spring 2013 LA TECH
ppm and ppb conversions1 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
12-48CHEM 102, Spring 2013 LA TECH
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 c) 9.79 M d) 0.980
e) none of these
M.W. = 34.02 (H2O2)
Problem
12-49CHEM 102, Spring 2013 LA TECH
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
12-50CHEM 102, Spring 2013 LA TECH
Comparison of Concentration Terms
12-51CHEM 102, Spring 2013 LA TECH
11) Compare the advantages and disadvantages of these solution concentration parameters.
12-52CHEM 102, Spring 2013 LA TECH
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).
12-53CHEM 102, Spring 2013 LA TECH
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).
12-54CHEM 102, Spring 2013 LA TECH
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).
12-55CHEM 102, Spring 2013 LA TECH
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).