THE 2008 FINAL EXAMINATION and FINAL GRADES Chemistry BC2001x
GENERAL INFORMATION AND ADMINISTRATIVE MATTERS
THE EXAMINATION ITSELF
The final examination in Chemistry BC2001x will be given on THURSDAY DECEMBER 18,
from 9:00 AM to noon, in Room 202 ALTSCHUL (the room in which the lectures are given).
The final examination will consist of 8 to 10 questions and problems, similar in style and scope to
those on previous examinations and those assigned for you for practice and to hand in throughout
the semester. As usual, there will be mixture of computational problems, problems relying partly
on memorized facts and procedures, and short-answer problems designed to test conceptual
understanding and to spot-check knowledge of various topics not otherwise covered.
About half of the final examination will focus on recent material: oxidation-reduction reactions,
electrochemical cells, thermochemistry, Gibbs free energy, thermodynamics and chemical
equilibrium, and qualitative analysis. The rest of the exam will review material taken from the
beginning of the course through equilibria. Some questions may combine material from different
parts of the course, including laboratory, and require you to put it all together. Knowing chemical
names and formulas, solubilities, and how to write net ionic equations is essential.
DECEMBER OFFICE HOURS
Regular office hours apply through Friday, December 5. I will hold special office hours from 2 to
4 PM daily between Tuesday December 9 and Wednesday December 17. Come to office hours
with your questions as often as you want. I will not answer questions like "Are we responsible
for…?" or “Do we have to know..?” but any chemistry question, no matter how fundamental, is
appropriate and welcome. As is my usual practice, everyone may join in when there are other
students from this class asking questions. You often learn from other people's concerns.
DEFERRED FINAL EXAMINATIONS
Barnard College has a strict policy for deferred final examinations: see Dean Blank's memo.
You may take a deferred final examination for one of two reasons only:
1) serious illness, requiring a visit to the health service or bed rest;
2) a death in the family or other serious personal emergency.
Absence from the final examination for any other reason results in an unalterable grade of zero.
If a serious health problem or emergency situation arises so you must miss the final exam,
you must call Prof. Chapman (854-2098) and your Class Dean in the Dean of Studies office
(854-2024) on or before December 18. I supply the registrar with deferred examinations only
for those students whose absences have been reported. All others get a grade of zero.
Deferred final examinations are administered by the Registrar during the first week of classes in
the spring term. No rescheduling is possible. Any student who must take a deferred examination
should make all the arrangements herself with the Registrar, 107 Milbank.
THE FINAL EXAMINATION Chemistry 2001x
STUDYING FOR THE EXAMINATION
1. Focus on basic operations, and practice them in different ways until you are fluent in how to
(a) convert mass to moles and moles to mass for atoms, molecules, and formula units
(b) find molar ratios from chemical formulas and from balanced chemical equations
(c) draw Lewis electron-dot diagrams, use VSEPR to predict molecular geometry and polarity;
(d) write balanced chemical equations, including net ionic equations, for all the various types
of chemical processes discussed in this course
(e) write balanced oxidation half-reactions and reduction half-reactions in both acid and base,
and combine these to give net ionic oxidation-reduction equations
(f) interconvert among moles, volumes, and molar concentrations of solutions
(g) determine which reagent, if any, is limiting and which are in excess for any reaction
(h) determine the equivalence point for any reaction that can be carried out as a titration
(i) compare reaction quotients Q and equilibrium constants K for any chemical reaction to
predict the direction of change for any mixture not at equilibrium
(j) write correct equilibrium constant expressions for any given reaction, and the expressions
for Ksp , Ka , Kb , and Kw in particular given only the formula of the appropriate substance
(k) use balanced chemical reaction equations and equilibrium constants K in general, and Ksp ,
Ka , Kb , and Kw in particular, to determine all the final concentrations or final pressures at
equilibrium given any initial conditions
(l) make appropriate use of approximations in equilibrium calculations, and check them
(m) use information implied by the structure of the periodic table
(n) apply the ideal gas law to single gases, to gas mixtures, and to reacting gas systems
(o) construct and interpret phase diagrams of pure substances and P-X for binary liquids
(p) interconvert between [H3O+ ] and pH, [OH− ] and pOH, Kw and pKw , Ka and pKa ,
Kb and pKb , K and log10K, in both directions
(q) construct and interpret titration curves for any type of monoprotic acid-base titration
(r) combine known equilibrium constants, such as Ksp , Ka , Kb , or Kw , to calculate the value
of an overall equilibrium constant K in reactions involving simultaneous equilibria
(s) interpret conventional electrochemical cell diagrams and construct electrochemical cells
(t) use tables of half-cell reduction potentials to calculate Δℰ °cell and K for any given cell
(u) use thermodynamic data tables to calculate heats of reaction ΔH°, entropy changes ΔS°,
Gibbs free energy changes ΔG°, and equilibrium constants K for any chemical reaction
(v) understand the concepts and operations associated with the experiments you carried out in
lab (but not the specific details of the procedures). Write net ionic equations.
2. Do NOT memorize:
a) Numerical values of atomic weights, R, NA , Ksp , Ka , Kb , Kw , ℰ o, kN, ℱ , ΔHf°, and the
like. All numerical values that you might need are always supplied on data sheets.
b) the van der Waals gas equation
c) Postulates of the kinetic theory of gases, or the derivation of PV = 2/3 Etrans
d) uncommon exceptions to solubility rules, or rules about slightly soluble or reactive salts
e) the Henderson-Hasselbalch equation relating pH and pKa
f) Equations related to distribution diagrams
3. The data sheets supplied with the final examination can be viewed on the web.
In addition to the periodic chart, which you use for exact atomic weights, they include:
(a) fundamental constants, conversion factors, and selected additional data
(b) values of selected equilibrium constants Ka and Ksp
(c) values of selected standard reduction potentials ℰ °
(d) selected thermodynamic data ΔHf°, S°, and ΔGf°
THE FINAL EXAMINATION Chemistry 2001x
4. Do memorize:
(a) complete key definitions (not the exact wording, but a thorough, complete understanding):
atomic weight, mole, molecular weight, ionic solid, molecular substance, phase, solution,
solubility, electrolyte, Ksp , acid, base, conjugate acid-base pair, pH, Ka , Kb , Kw , buffer,
titration, equivalence, indicator, excess reagent, limiting reagent, oxidation, reduction, cell,
electric potential difference, equilibrium, energy, enthalpy, entropy, Gibbs free energy,
standard enthalpy of formation, third law entropy.
(b) units of key quantities [for example, atomic weight and molecular weight (g / mole);
concentration units: weight %, mole fraction X, molality m (moles solute / kg solvent),
molarity M (moles solute / liters solution = mmoles / mL); electric potential difference
(volts = J / C = (energy / unit charge); ΔH and ΔG (kJ / mole); ΔS (J / K-mole)]
(c) names and symbols of the common elements shown on the periodic table overview sheet
(d) names and charges of all cations and anions listed on the inorganic nomenclature sheet
(e) procedures for recognizing and rules for naming simple ionic and molecular compounds
(f) names and formulas of the strong acids and the strong bases listed on the handout sheet
(g) solubility rules and important exceptions for salts of common ions, given on the sheet
(h) how to recognize strong electrolytes, weak electrolytes, nonelectrolytes, acids, and bases
(i) general rules and conventions for writing net ionic equations for reactions in solution
(j) general rules and conventions for writing equilibrium constants for chemical reactions
(k) rules for finding oxidation states of atoms in molecules and ions
(l) procedures for balancing oxidation or reduction half-reactions in acid or in base solution,
and for combining half-reactions to obtain net ionic oxidation-reduction equations
(m) rules for calculating the standard electrochemical cell potential from reduction potentials
(n) rules for calculating changes in energy, enthalpy, entropy, and Gibbs free energy
(o) Le Chatelier’s principle and its various specific applications
(p) fundamental principles, relationships, and equations:
(i) conservation of atoms of each element − used in balancing chemical reaction equations
(ii) the general structure of the periodic table and the many implications of its arrangement
(iii) the ideal gas law: PV = nRT
(iv) Raoult’s law for the vapor pressure of ideal solutions: PA = XAℓ PA°
(v) the limiting laws for the four colligative effects on solutions discussed in lecture:
ΔPA = i PA°XBℓ ; ΔTbp = i Kb m; ΔTfp = i Kf m; Π = i cRT
(vi) definitions for the particular types of equilibrium constants Ksp , Ka , Kb , and Kw
(vii) Ka Kb = Kw for any conjugate acid-base pair
(viii) the definition pH = −log [H+ ] and [H+ ] = 10 − pH and analogous definitions
(ix) From the Nernst equation: Δℰ cell = Δℰ °cell – (kN/n) log10 Q
the relationship Δℰ °cell = + (kN/n) log10 K or log K = nΔℰ °cell /kN
(The Nernst equation and kN (0.05916 V at 25°C) are on the data sheet)
(x) When P is constant: ΔH = ΔE + PΔV; in general ΔG = ΔH – TΔS
(xi) Gibbs free energy chemical reactions: ΔG = ΔG° + RT ln Q → ΔG° = – RT ln K
at 25°C, 2.303RT = 5.708 kJ/mol, ΔG° = − (5.708) log10 Keq → log K = –ΔG°/5.708
(The numerical constant 5.708 kJ/mole at 25°C will be supplied as data)
(xii) the criteria for the direction of spontaneous change and for equilibrium:
reactions proceed spontaneously to the right if ΔG < 0, Δℰ cell > 0, and Q < K
reactions are at equilibrium when ΔG = 0, Δℰ cell = 0, and Q = K
THE FINAL EXAMINATION Chemistry 2001x
WORDS of WISDOM on TAKING THE FINAL EXAMINATION
1) NEVER EVER stay up late the night before an examination. You must be able to think
clearly and quickly during examinations, not merely repeat masses of memorized material.
Always get a good night’s sleep. Be on time, and arrive relaxed and ready. Since the exam is
at the end of the exam period, dorms can be noisy and students exhausted. Try to be rested!
2) The final examination will last from 9:00 to 12:00 exactly. If you arrive late, you will not be
given extra time to complete the examination.
3) Read quickly through the entire examination first before you start working. You may answer
the questions in any order, so work selectively: do the questions you know best first.
4) Read each question twice through before answering. Think before you write anything.
Understanding correctly what a question asks is key to solving that problem. You should
understand the situation qualitatively, know what is happening, before doing any calculations.
5) Budget your time. The final examination lasts 180 minutes. If the total credit for the exam is
250 points, say, then do not spend much more than 20 minutes on a 25 point question.
6) Set up problems clearly: partial credit is given, so write something. Define symbols used.
Write out any general formulas or any chemical equations relevant to the problem. You must
SHOW all your work, both the reasoning and the calculations, to receive full credit for it.
7) Try each question. You should be able to get at least some partial credit for each question.
8) Units and significant figures matter: unless both are specified completely and accurately, final
answers are not completely correct.
9) Bring a working calculator and know how to use it. (I will bring a couple of spares in case of
a calculator failure, so ask me if you need one.)
10) If you are confused or frustrated by a problem, don’t panic. Either raise your hand to ask for a
clarification, or stop work on that problem immediately and go on to some other question. It is
often the case that you will later come back and easily understand what you were missing.
If you need to get up, splash cold water on your face, or get a drink of water, just ask to do so.
Get back to dealing with the problems; do not just sit there doing nothing.
FINAL EXAMINATION GRADES and COURSE GRADES
Do not phone or e-mail to ask me about your grade. We will grade the exams as fast as we can
(Dr. Alexander and Mrs. Jebejian help me), but I need to check all data carefully. Your course
grade will be posted electronically by the registrar's office soon after it is submitted.
Barnard College rules require that all final examinations be kept by the instructor for one year.
Your final examination will be available for inspection in my office throughout that period. You
may, of course, also come any time to discuss your grade with me. But keep in mind that grades
at Barnard may be changed only if there has been a clerical error.
SOME FINAL WORDS OF ADVICE
The final exam counts only 23% of your overall course grade. If you have been faithfully
submitting problem sets, doing a good job with your lab reports, and have done ok on the exams
so far, much of your grade is already well-established. There is a lot of material in this one
semester of chemistry. As you study, remind yourself that you don't have to know everything:
your objective in taking the final exam should be to show what you have learned, and you have
learned a lot! To do your best, you need to be able to think and reason clearly, so the most
important thing is to be as calm and rested as possible.