Review 1
For test 1 Chapter 14 and 15
Test will have part 1 Multiple choice and
part 2 show work problems
One can receive partial credit in Multiple
choice if work is shown or concept is
explained
Concentration Units
Molarity (M)
moles of solute
M =
Mole Fraction (X)
liters of solution
Molality (m)
Xi =
moles of solute
m =
moles solute (i)
Total moles in solution
mass of solvent (kg)
Weight (mass) %
•
Percent by volume: milliliters of
solute/milliliters of solution (then
multiplied by 100%)
•
Mass/volume percent: grams of
solute/milliliters of solution (then
multiplied by 100%)
mass of solute x 100%
% by mass = mass of solute + mass of solvent
Henry’s law for Gas solubility Sg (mol/L)
Sg =KHPg
ROULT’s Law
Psolution = Xsolvent  Po
Psolution = the vapor pressure of a mixture of solute and solvent
Po = the vapor pressure of the pure solvent
Xsolvent = the mole fraction of the solvent.
If 2 liquids A and B are mixed then Vapor of each of them in the
mixture are
PA = XA P0A
PB = XB P0B
Colligative Properties of Nonelectrolyte Solutions
Colligative properties are properties that depend only on the number of solute particles in
solution and not on the nature of the solute particles.
0
P
=
X
P
Vapor-Pressure Lowering
1
1 1
Boiling-Point Elevation
DTb = Kb m
Freezing-Point Depression
DTf = Kf m
Osmotic Pressure (p)
p = CRT
Electrolyte Solutions (i is Vant Hoff factor)
Boiling-Point Elevation
DTb = i Kb m
Freezing-Point Depression
DTf = i Kf m
Osmotic Pressure (p)
p = iCRT
4
Chapter 15 Kinetics
Average Rate
D [reactant ]
change in concentration D [product ]
Rate =
=
=change in time
D time
D time
In general for the reaction:
1 DA
Rate of reaction  
a Dt
(M/s)
Initial Rate
aA + bB  cC + dD
1 D B
1 D  C
1 D D



d Dt
b Dt
c Dt
Rate  k [A]x [B]y
x and y are the reactant orders determined from experiment.
x and y are NOT the stoichiometric coefficients.
Integrated Rate Laws- Remember the graphs!!
Rate = k [A]o
Zero order kinetics
[A]t  [A]o = kt
Half life t1/2 = [A]o /2K
unit of k =??
Rate = k [A]1
First order kinetics
ln[A]t = ln[A]o kt
Half life t1/2 = 0.693/k
[A]t
 ekt
[A]o
 [A]t 
ln 
 kt

 [A]o 
Second order kinetics
Rate =k
unit of k =??
[A]t  [A]o ekt
Rate = k [A]2
1
1
 kt 
 A t
 A 0
Half life t1/2 = 1/[A]oK
unit of k =??
The Arrhenius Equation
k = Ae
-Ea
RT
k is the rate constant
T is the temperature in K
Ea is the activation energy
R is the ideal-gas constant
(8.314 J/Kmol)
A is known the frequency or pre–exponential factor
æ k 2 ö Ea
ln ç ÷ =
è k1 ø R
æ1 1ö
´ç - ÷
è T1 T2 ø
Both A and Ea are specific to a given reaction.
Catalysts
Lowers activation energy
Changes Reaction mechanism
But does not change Enthalpy
Speeds up reaction
Uncatalyzed reaction
Catalyzed reaction
• Reaction Mechanisms, Overall Reaction, Molecularity (unimolecular, bi molecular etc for each
Step in a multistep reaction pathway)
• Intermediates
• Rate Detreminating step is the slowest step and makes up the overall reaction rate law.