AP Review Unit 2 - District 155 D155 Homeww2.d155.org/clc/tdirectory/JSayles/Shared Documents/AP...
Transcript of AP Review Unit 2 - District 155 D155 Homeww2.d155.org/clc/tdirectory/JSayles/Shared Documents/AP...
Copyright 2004 - John Sayles 1
AP Review Unit 2
Solutions
and
Solution Equilibrium
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The “Solution Process”
Break solute-solute bonds END
IMF’s if covalent
Ionic bonds if ionic
Break solvent-solvent bonds END
Likely IMF’s
Form solute-solvent bonds EX
The payoff; if this goes well, sol’n forms
Known as solvation (or hydration)
The reason “like dissolves like”
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The Dissolving of Lithium Fluoride in Water
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12_8
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Solvation of Ions
12-7 Copyright © Houghton Mifflin Company. All rights reserved
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Solubility
Def’n: max. [ ], [ ] at equilibrium, [ ]
of a saturated solution
Depends on
Nature (polarity) of solute and solvent
Temp (endo or exo?)
Pressure, for gases [ ]x prop to PPx
Temp, surface area and stirring affect rate
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Comparison of Unsaturated and Saturated Solutions
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Effect of Pressures on Gas Solubility
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Solubility Rules
See page 136
Solubles
Anions: nitrates, acetates, halides, sulfates (except Ca, Sr, Ba)
Cations; Group I, ammonium
Insolubles
Anions: sulfides, hydroxides, carbonates, phosphates
Cations: Ag, Pb, Hg
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Van t’Hoff Factor
Covalent solute crystal split into molecules
Van t’Hoff factor = i = 1
Covalent solutes are non-electrolytes
Ionic solute crystal splits into ions
For AxBy, van t’Hoff factor = x + y
Radicals do not split into pieces; they’re
covalently bonded
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Units of Concentration
Molarity = M = moles solute/liter solution
molality = m = moles solute/kg solvent
Custom-made for BP elev and MP depression
Mole fraction = X = moles solute/moles total
Used in Dalton’s (PP’s) and Raoult’s laws (VP lowering)
Percent = % = mass solute/mass total
To convert between units
Pick sample = denominator of given unit
Use density of solution to change grams <--> liters
Do #55 on page 544
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Colligative Properties
Ways in which a solution differs from the
pure solvent
Find these on the formula sheet
VP is lower (Raoult’s Law)
BP is higher, since the VP is lower
MP is lower; the liquid range is extended twice
Osmotic pressure created in presence of SPM
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Semipermeable
Membrane
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Demonstration of Vapor-Pressure Lowering
Copyright © Houghton Mifflin Company. All rights reserved 12-15
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Using Colligative Properties
Great way to count moles for a non-gas!
Make sol’n and compare BP (or other prop) to
that of pure solvent
Use formula to calculate moles, then MW
kf and kb depend on solvent; found in tables
Calculate m from formula
Calculate moles from m
Do #67 on page 545
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Solution Equilbrium Ksp = [cation]x[anion]y for CxAy
Just like any other K; used in same ways
Estimate solubility
Calculate one [ ] given the other [ ]
Predicting PPT
Calculate Q and compare to Ksp
Solubility <---> Ksp
If solubility = x, Ksp= x2, 4x3, … , 108x5
If common ion is present
Make grid
Make one [ ]initial ≠ 0
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Solubility Product Constants, Ksp, at 25º C
Table 17-B Copyright © Houghton Mifflin Company. All rights reserved
T17_1B
Mg3(AsO4)2
MgCO3
Mg(OH)2
MgC2O4
MnS
Hg2Cl2HgS
Ni(OH)2
NiS
AgC2H3O2
AgBr
AgCl
AgCrO4
AgI
Ag2S
SrCO3
SrCrO4
SrSO4
Zn(OH)2
ZnS
Magnesium arsenate
Magnesium carbonate
Magnesium hydroxide
Magnesium oxalate
Manganese(II) sulfide
Mercury(I) chloride
Mercury(II) sulfide
Nickel(II) hydroxide
Nickel(II) sulfide
Silver acetate
Silver bromide
Silver chloride
Silver chromate
Silver iodide
Silver sulfide
Strontium carbonate
Strontium chromate
Strontium sulfate
Zinc hydroxide
Zinc sulfide
2 x 10-20
1.0 x 10-5
1.8 x 10-11
8.5 x 10-5
2.5 x 10-10
1.3 x 10-18
1.6 x 10-52
2.0 x 10-15
3 x 10-19
2.0 x 10-3
5.0 x 10-13
1.8 x 10-10
1.1 x 10-12
8.3 x 10-17
6 x 10-50
9.3 x 10-10
3.5 x 10-5
2.5 x 10-7
2.1 x 10-16
1.1 x 10-21
Formula KspSubstance