Exam II Objectives
Chem142
Dr. Haefner
The following is a list of topics you should know for the upcoming exam. It is designed only as a study
aid and is in no way intended to be comprehensive. You are still responsible for all material covered in
class and in the assigned readings. I STRONGLY recommend you work as many different problems as
possible until you can comfortably and reliably solve them without the notes or book.
Topics from Chem 141 you may need to know:
Identify and name ionic compounds. Nomenclature!!!!
Determine % composition.
Balance equations and use coefficients in stoich. calc.
Be able to determine empirical and molecular formulas.
Understand the fundamental gas laws and how to use them to determine Molar Mass of a gas
(MW=dRT/P)
The relationship between mole fraction of a gas (vapor) and its partial pressure: a = Pa/Ptotal
Dalton’s law of partial pressure (Ptot = PA + PB + PC ….)
Conversion between the pressure units atm, torr and mm Hg
Strong/Weak Acids/Bases
Solubility Rules and Precipitation
Identify and name ionic compounds. Nomenclature!!!!
Conversion between the pressure units atm, torr and mm Hg
Be able to draw a good Lewis structure for a molecule or ion
Determine the molecular geometry of a molecule (VSEPR)
Predict if a molecule has a dipole moment.
Chapter 12: Equilibrium
Interpret chemical equilibrium as a dynamic process involving change at the molecular level
Be able to write the equilibrium expression for a given reaction (don’t include solids and liquids)
Be able to write a chemical reaction given an equilibrium expression
Be able to determine K for a reaction given the equilbrium constants for several related reactions
(manipulate equations and their equilibrium constants
Determine the equilibrium constant of a reaction given equilibrium concentrations
Be able to use the magnitude of an equilibrium constant to predict whether products or reactants are
present at equilibrium
Be able to predict the relative magnitude of an equilibrium constant for certain reactions (Acid/base,
ppt/dissolving)
Be able to use Le Chatelier's principle to predict how the equilibrium composition of a reaction mixture
is affected by
(i) adding or removing reagents
(ii) changing the pressure, volume and temperature of a reaction
(iii) adding an inert substance
(iii) adding a catalyst.
Be able to describe differences between rates (kinetics) and equilibrium (thermodynamics)
Use the reaction quotient, Q, and the equilibrium constant, K, to determine the direction of a reaction
given pre-equilibrium concentrations
Be able to determine equilibrium concentrations given K and pre-equilibrium concentrations
Determine new equilibrium concentrations for a reaction following a change in amount of a species,
pressure, volume, or temperature of the system.
Know when it is appropriate to make approximations in solving equilibrium problems (5 % rule)
Be able to determine K for an equilibrium given at least one of the equilibrium concentrations (or given
data that allows you to calculate the equilibrium concentration from an analysis reaction.)
Chapter 13: Acids and Bases
Be able to dentify species as Bronsted acids or bases and write formulas for their conjugate acids and
bases
Identify a strong acid from a weak acid and a strong base from a weak base This concept is critical for
understanding buffers and acid-base titrations
Define the acid and base dissociation constants and how they are related
Be able to write acid/base dissociation equilibria for any compound
Be able to define and provide examples of the following as well as write equations that demonstrate their
behavior:
(a) Arrhenius Acid/Base
(b) Bronstead Acid/Base
(c) Lewis Acid/Base
Be able to convert between pH, pOH, [H3O+], and [OH-]. Given one should be able to find all the others
Understand the relationship between Ka and Kb for a conjugate acid/base pair (Ka x Kb = Kw)
Be able to calculate the pH and pOH for any solution:
(i) Strong acid present
(ii) Strong base present
(iii) Weak acid ONLY
(iv) Weak base ONLY
(v) Weak Acid/Base Conjugate pairs (Buffers *next exam)
In General:
a. Write out majors species
b. Identify them as SA, SB, WA, WB or SI
c. Look for stoichiometric reactions (** next exam)
(i) SA + SB
(ii) SA + WB
(iii) WA + SB
Carry out stoichiometric reactions using MOLES, one of the species must go to 0 moles at the end of
the reaction.
d. After reaction (if any) identify new Major species and their new concentrations
e. Find pH based on what species are present
Be able to calculate the percent ionization of an acid or base
Be able to calculate acid or base concentration from pH given Ka or Kb
Be able to calculate Ka or Kb from pH info
Be able to find pKa and pKb from Ka and Kb.
Be able identify whether an ion will produce an acidic, basic or neutral solution and write the proper
equilibrium that accounts for its behavior
Be able to identify an acid or base dissociation equilibrium reaction and its associated equilibrium
constant Ka or Kb.
Be able to identify whether a salt will produce an acidic, basic or neutral solution when dissolved in
water
Be able to predict the relative acidity/basicity of various species
Be able to identify and define an amphoteric species
Be able to identify and write reactions that correspond to the acid/base behavior of binary oxides
Be able to order solutions (with out calculations) according to pH, pOH, acidity, and basicity
Be able to write an equilibrium equation that illustrates how a transition metal ion behaves as an acid in
aqueous solution
Be able to predict acid and base strength based upon structure (note that we only learned how to predict
acid strength but we can apply the fact that a stronger acid has a less basic conjugate base)
Be able to use resonance structures to explain acid/base behavior
Be able to order a series of compounds with respect to their pH.
Be able to predict whether an oxide will produce an acidic or basic aqueous solution and write a
balanced equation
Understand how resonance structures affect the stability of conjugate bases and therefore acid strength.
Identify which species may behave as Lewis acids and Lewis bases.
Be able to identify a lewis acid/base reaction
Use your homework assignments and quizzes as a guide to the types of problems that may appear.
However, be aware that you may encounter a problem that you have not seen before. If so, think about
the problem and extrapolate what you do know to the problem. Don't just memorize the mechanics of
doing a certain type of problem but understand the principles and fundamental concept behind the
problem. If you simply memorize mechanics, you will not do well.
Useful Constants and Equations
Planck's constant
Speed of light
Atomic mass unit
Boltzmann constant
Gas Constant
Faraday
h = 6.626 x 10-34 J•s
c = 2.9979 x 108 m/s
amu = 1.66054 x 10-27 kg
k = 1.38066 x 10-23 J / K
R = 8.31451 J / K
R = 0.08206 L • atm / K mol
F = 96,485 C/mole e-
Kf [Ag(NH3)2]+ = 1.7 x 107
Enthalpy of vaporization for H2O
Enthalpy of fusion for H2O
40.7 KJ / mol
6.02 KJ / mol
E = 2.31 x 10-19 J • nm (q1 q2 / r)
zero order:
[A] = -kt + [A]0; t1/2 = [A]0/2k
(KE)avg = 3/2 RT
first order:
ln [A] = -kt + ln [A]0; t1/2 = ln 2/k
urms = (3RT / M)1/2
second order: [A]-1 = kt + [A]-1; t1/2 = 1/k[A]0
ln(P1/P2) = H/R (1/T2 – 1/T1)
k = Ae-Ea/RT
sc: l = 2r;
ln(k2/k1) = Ea/R (1/T1 – 1/T2)
bcc: l = 4r / (3)1/2
T = i K m
fcc l = r (8)1/2
=iMRT
G = H - TS
-b ± b2 - 4ac
2a
x=
G = G° + RTlnQ
ln(K2/K1) = /R (1/T1 – 1/T2)
 = ° - (RT/nF)lnQ
 = ° - (0.0592/n)logQ
E = mc2
E = h
 = c
PMm = dRT