ap notes chapter 14 solutions and their behavior
TRANSCRIPT
AP Notes Chapter 14
Solutions and Their BehaviorSolutions and Their Behavior
Solutiona homogeneous mixture of two or more components
Solutecomponent(s) present in lesser quantity
Solventcomponent present in greater quantity
A saturated solution contains the maximum quantity of solute that dissolves at that temperature.
An unsaturated solution contains less than the maximum quantity of solute that dissolves at that temperature.
Supersaturated Solutions contain more than is possible and are unstable.
Liquid Solutions1. molarity, M
solution L 1
solute molM
2. mass %
100nsol' mass
AmassA%
3. mole fraction, (A)
nsol' mol
AmolA
solute mol solvent mol
AmolA
1i
4. molality, m
solvent kg
solute molm
MolarSol’n
MolalSol’n
Ideal Solution
P(A)0 is the VP of volatile solvent A at a particular temperature
Properties of Ideal Solutions
if P(A) is the vapor pressure of a solution of
volatile solvent A, and non-volatile solute B,
then P(A) (A)
or P(A) = (A) . P(A)0
[Raoult’s Law]VP Solution
for a solution where 2 components are volatile
P(T) = P(A) + P(B)
= (A) . P(A)0 + (B) . P(B)0
Ideal Solutions
Positive deviation
Real Solutions
Negative deviation
Properties of Ideal Solutions
if P(A) is the vapor pressure of a solution of
volatile solvent A, and non-volatile solute B,
then P(A) (A)
Properties of Ideal Solutions
2. NO volume changes occur
during the solution process
Properties of Ideal Solutions
3. NO heat is evolved or absorbed during
the solution process
Raoult’s Law is valid only for VERY dilute
solutions or some nonpolar - nonpolar
solutions
Solubility Factors
likedissolves
like
Polar H2ONon-polar I2
Non-polar CCl4
Polar H2O
Non-polar I2
Non-polar CCl4
Solvent Extraction
O //H2C-O-C-R | O | //H2C-O-C-R
| O | //H2C-O-C-R a “fat”
+ 3 NaOH
R = (CH2)16CH3
H2C-O-H | | H2C-O-H
| | H2C-O-H
O \\+ 3 R-C-O- Na+
a “soap”
SurfactantsSurfactants
Surface acting agentsSurface acting agents Lowers surface tensionLowers surface tension Enables solvationEnables solvation Those used for cleaning are Those used for cleaning are
commonly called detergentscommonly called detergents
Temperature
SOLIDS
GASES
Pressure
Sg = kHPg
Henry’s Law
ColligativeProperties
Property whose magnitude depends
solely on the concentration of
particles, NOT on the nature of the particles
ElectrolyteElectrolyte
solute that forms solute that forms ions in solution ions in solution
which conducts a which conducts a currentcurrent
Non-ElectrolyteNon-Electrolytesolute that remains solute that remains
as molecules in as molecules in solution which solution which
does NOT conduct does NOT conduct a currenta current
molalitymoles of substance measured through
mass before solution process
takes place
Colligative Properties of
Non-Electrolytes
1. Vapor Pressure LoweringVP Lowering
1. Vapor Pressure Lowering
A = solvent ; B = solute
A + B = 1
1. Vapor Pressure Lowering
A = solvent ; B = solute
A + B = 1
A = 1 - B
but: PA = APo
A
thus: PA = (1 - B) Po
A
or: PA = PoA - BPo
A
oA
AoA
B P
PP
NOTE: the lowering of the vapor pressure of the pure solvent A is a function only of B (solute)
boiling point temperature where vapor pressure of solvent equals the
atmospheric pressure
2. Boiling Point Elevation
Tbp m
Tbp m
Tbp = kbpm
where kbp = a constant that is a function of the solvent
units on kbp ?
units on kbp ?
solute mol
solvent kgK
m
Tkbp
Freezing WaterFreezing Solution
3. Freezing Point Depression
Tfp m
Tfp m
Tfp kfp m
kfp = freezing point constant
kfp = kbp
for the same solvent
OSMOSISthe flow of solvent into
a solution through a semi-permeable
membrane
ExamplesEgg Rxn
Microscopic PerspectiveEgg Explanation
Macroscopic Perspective
4. Osmotic Pressure
the pressure that must be applied to a
solution to stop osmosis
ReverseOsmosis
4. Osmotic Pressure
= osmotic pressure
V = nB R T
or
= MB R T
MB = Molarity of solute
Colligative Properties of Electrolytes
Must adjust for degree of
dissociation
i = van’t Hoff factorTbp = i kbp mTfp = i kfp m
= i
Compound iNaClMgSO4
MgCl2
FeCl3
Compound iNaCl 1.9MgSO4 1.3MgCl2 2.7FeCl3 3.4
