Review 1

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
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
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
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.
Vapor-Pressure Lowering
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
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
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
 ekt
 [A]t 
ln 
 kt
 [A]o 
Second order kinetics
Rate =k
unit of k =??
[A]t  [A]o ekt
Rate = k [A]2
 kt 
 A t
 A 0
Half life t1/2 = 1/[A]oK
unit of k =??
The Arrhenius Equation
k = Ae
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.
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.