Chemblog!

AP: we did our second part II exam. A couple of pointers: as you witnessed, it is very easy to make careless errors on questions 1 and 2. On GAS LAW questions, simply DRAW a large container of any and all gases initially present so that you don't forget to include them all in your calculations. Draw another container with all gases that remain after the reaction so that you can answer any remaining questions. The general theme of good test-taking is to TAKE PAINS to do these minor bookkeeping/drawing activities to avoid "dumb/stupid" errors. For aqueous equilibria questions, draw a LARGE beaker containing all species that are in solution (including spectator ions).
Very good work, today. Thanks for catching my careless errors (naturally, I would have caught those errors as I checked my work?)
We have more part II's and a part I later this week which will prep us for a solid and, I hope, affirming performance this Saturday. Saturday is Kentucky Derby Day and you will be having your own AP Chem Derby in the Board Room that morning. Get psyched!

Honors: we went over several characteristics of acids and bases. We wrote and balanced several acid-base neutralization reactions. We then explained the definitions of Arrhenius acids and bases and Bronsted acids and bases. We practiced how to locate the conjugate acid-base pairs in a Bronsted acid-base reaction. More on that tomorrow.

Regents: we reviewed characteristics of acids and bases. We then explained the definitions of Arrhenius acids and bases and Bronsted acids and bases. We practiced how to locate the conjugate acid-base pairs in a Bronsted acid-base reaction.

I was blown away by the usefulness and effectiveness of the "Cool School" website. There are two chem courses, Chemistry 11 and 12, that collectively cover a year of chemistry. Each unit is broken into subtopics. There are video lab demos and interactive flash exercises in which YOU manipulate the variable and literally see the effect of your variations.
Check it out. It can really help to reinforce the information that you are learning:
Cool School Chem 11
Cool Schoo Chem 12

Regents: thanks to Anthony G., who found an error in the answer key (!), the class average on the last test went up two points to an 81! Good eye!
Today, we discussed characteristics of acids and introduced the conceptual Arrhenius and Bronsted definitions of acids.
I'll assign some reading for this unit over the weekend.

Honors: we finished our discussion on delta G, entropy, and enthalpy. We did several examples in which we predicted the temperature at which a process or reaction becomes spontaneous.
We began our acid-base-salt unit by looking at characteristics of acids and see what happens when a strong or weak acid is dissolved in water.
I'll assign some reading for this unit over the weekend.

AP: we wrapped the Nuclear unit noting the correct conversion factor in Einstein's equation. If the mass defect is calculated in amu, you must convert that to kg by multiplying by
1.66 x 10^-27 kg per amu. Then, plug the mass defect in for delta m in E = delta m c^2 . This energy is the nuclear binding energy. Finally, to get the binding energy per nucleon, divide by the mass of the isotope's nucleus (in kg or amu). Fe-56 has the highest binding energy per nucleon and the greatest mass defect per nucleon.
We then looked at useful radioisotopes including C-14 (important in carbon dating and in elucidating biochemical pathways), U-238 (its ratio to its 14-step decay series stable product, Pb-206 in a rock sample determines the age of crazy old rocks/the Earth), and others.

We then began a part I section of the 1989 exam. The exams begin with some quick-start questions. It is crucial not to rush through these; these questions are simple enough that you will naturally do them quickly even if you are meticulous and careful (underlining keywords, DRAWING examples, diagrams, definitions, etc.). Start the test strong and accurately; later on, you will have to INITIALLY pass on a few weed-out questions that are DESIGNED TO CONFUSE, FRUSTRATE, and decimate the average test-taker. SEE those questions for what they are and coolly sidestep them, initially.

When you complete this exam, this weekend, do so under TIMED conditions! We spent about 15 minutes on the exam so try to finish the rest of the test in 75 minutes. If there are questions remaining thereafter, answer them with a different color pen or a pencil. After that, show all work that you didn't have time to explicitly show during the timed portion so that you can reinforce the reasoning involved in answering these questions. Email me if you are flummoxed by a given question (remember that sketchy CaCO3 vs. BaSO4 question).
Good luck. I will post Monday's part II exam for preview.

Clear your calendar for next Saturday, AP Exam trial day. You will be taking the entire 2002 AP Chem exam under timed conditions in the Board Room. On that day, you will see clearly where you stand in your quest for a 5. I cannot overemphasize the importance of being in that Board Room next Saturday morning at 10AM with your classmates and taking that test as the real deal. The test takes 90 minutes for Part I; then we take a ten-minute break followed by a 90-minute part II (40 minutes with a calculator, 50 minutes without a calculator). I grade the part I's while you all take the part II so we can generally finish grading and analysis in 45 minutes. Then, you'll have your AP score! Of course, don't ruin this simulation by even accidentally looking at the 2002 exam beforehand. The test does not in any way shape or form count towards your course average. It is simply the best diagnostic tool to show you how to focus your last ten days of study before the 2007 AP exam.
Fortunately, this year, we have a little more time for review so, wherever you may have a weakness on that official test, you have time for improvement. I will hold an optional timed exam the following weekend (either way, I will give you a copy of that exam).

AP: we went nuclear today and discussed the five types of nuclear decay and the proximate reason for said decay: the neutron to proton ratio of the nucleus. We discussed nuclear decay kinetics (always first order) and applications thereof: carbon dating. We will briefly discuss other nuclear applications, tomorrow. I explained the strong force of nature and nuclear binding energy per nucleon. The isotope with the greatest binding energy per nucleon is Fe-56. All lighter isotopes tend to undergo fusion in order to form more strongly bound, more stable nuclei; all heavier isotopes tend to undergo fission reactions to form more stable nuclei.
We then looked at "penetrating power" and particle energies. Gamma rays are the most penetrating (can only be stopped by thick slabs of lead and/or concrete) but have the least energy per particle (though each gamma photon has a relatively high energy compared to the energy of a visible photon); beta particles have intermediate penetrating power (can be stopped by wood or thick cardboard) and intermediate energy per particle; alpha particles have the least penetrating power (can be stopped by paper or clothing) but have the highest energy per particle.

Honors: we did some qualitative "common ion" Le Chatelier problems. We then looked at the last part of our current unit: predicting spontaneity of a reaction or process by considering the change in enthalpy, entropy (chaos/randomness), and Gibbs Free Energy.
We defined entropy and considered various ways of predicting the entropy change of a process or reaction. We looked at the four possible combinations of enthalpy change and entropy change at a given temperature and considered the net change in Gibbs Free Energy in order to predict whether a given reaction or process is spontaneous.
Tomorrow, we will finish this part of the unit and get a jump on the Acids, Bases, and Salts unit.

Regents: we had our kinetics/equilibrium/Le Chat exam today...class average: 82
:(

Regents: we finished the equilibrium unit with examples of spontaneous and nonspontaneous reactions/processes.
The test tomorrow will cover all of the Kinetics/Equilibrium unit up to today's notes from that unit (enthalpy, entropy, and spontaneous reactions/process). Make sure that you know how to apply Le Chatelier's Principle to any reaction or process.
Be careful. Write EVERYTHING out and take things step by step (ask the THREE questions) and do not rush. Use lots of scrap paper.

Honors: we had our Le Chat/Equilibrium Test today. Tomorrow, we will finish quantitative equilibrium calculations and begin our new unit: Acids and Bases.

AP: we began our formal AP exam review; we did questions 4 and 5; in the lab question, remember, the level of the gas must be equal to the level of the water outside the tube so that the internal and external pressure are equalized; then, to get the pressure of the collected gas, don't forget to subtract the Pvap of water at that temperature.
We then did question 2, which was from Chapters 6 and 7 on the Quantum atom.
Do the remaining questions for hw and hand them in by Friday. We have Nuclear day tomorrow, so have those notes downloaded for tomorrow.

AP- we had our Electro exam today; tomorrow, we finally begin our formal AP exam review during which I will emphasize test-taking skills and, of course, exam content knowledge. Download and preview the part II exam. We will likely do our first part I on Friday. Here is how these classes "work": you will have a part I or part II exam to preview/analyze the day before we do the exam in class. Come to class prepared with questions that you dislike/have trouble with/are sketchy about. We will do those immediately in class; then, whichever questions we do not cover, you will do for hw to be handed in the next day. Looking forward to finely honing your skills, which you already have "pre-honed" with your KARMA work. We are now approaching the stretch-drive in our race to a 5. Good times.

Honors: we looked at the various subscripts that are seen on equilibrium constants; these subscripts indicate the type of reaction or process that is occurring. They are all the same old thing though: an equilibrium constant, K.
We then took a more quantitative approach to K in which we MUST use the stoichiometry of the reaction/process as well as the correct K expression. With those two tools, we can solve for the actual equilibrium concentrations in any equilibrium problem.
Tomorrow, we have a test on equilibrium , Le Chatelier's Principle, explanation of Le Chatelier shifts in terms of forward and reverse rates of reaction, and equilibrium constant expressions. Extra help was light today, make sure that you are prepared for this test under timed conditions.

Regents: we discussed entropy/chaos/disorder as a driving force for any reaction/process that occurs naturally/spontaneously. We then did several problems in which we predicted whether the entropy change, delta S, was positive or negative.
The other driving force of a reaction/process is the stability/low potential energy of the products. Thus, exothermic reactions tend to be favored in nature because the products are more stable than the reactants in any exothermic reaction/process.
We then looked at delta G, the change in Gibbs Free Energy. When delta G is negative for any reaction/process, that reaction/process is spontaneous/occurs naturally without the need for a battery or continuous power source.
delta G = delta H - T delta S ; T is in Kelvin.

AP: we finished up the Electro unit with some quantitative electrolysis problems. We analyzed the reactions that occur at the anode and cathode for a given electrolysis. We then briefly discussed fuel cells emphasizing that these cells require a continuous supply of reactants which undergo a redox reaction to generate electrical energy/electricity.

Honors: we finished our Le Chatelier problems and introduced the Law of Mass Action and the Law of Chemical Equilibrium. We described how to write the correct equilibrium constant for any given reaction or process: always include aqueous and gaseous reactants and products; NEVER include solid or liquid reactants and products.

Regents: we did several problems in which we wrote the equilibrium constant expression and a couple of problems in which we calculated the value of the Keq by plugging in the equilibrium concentrations of the products and reactants into the equilibrium constant expression.

Here are links to various fuel cell types and schematics, schematics!
http://www.epa.gov/fuelcell/basicinfo.htm
Notice how various fuel cells have different "working temperatures" and efficiency ratings:
http://en.wikipedia.org/wiki/Fuel_cell

The usual: practice worksheet errors
Worksheet 1: Question 2, correct answer is C, not D. Question 7, the correct answer is 2,18,3,3,12.
Question 14: correct answer is A, NOT C.
Worksheet 2: Question 2b: answer is 1.58 x 10^-9 ; Question 2c: answer is 1.58 x 10^-10

Hey Varsity,
One of the AP Chem teachers from Colorado volunteered a link to his video review sessions. They are mp4 formatted videos so they can play on your ipods! I haven't seen them all but you can scroll through the sessions to any problems that interest you.
http://www.wpsdk12.org/~jbergmann/FOV1-00019CEA/FOV1-0001A2D4/

Here is a link to the review packet that is referred to during the review sessions.

So, big ups to Mr. Bergmann for his generous offer of knowledge. Again, I haven't seen most of the sessions so, if anything seems "different" or confusing, just let me know.
p.s. For Tuesday's exam, there will be a thermo question (I couldn't fit a calorimetry question on the last test) and a few descriptive chem questions with an emphasis on redox. The thermo question will involve calorimetry, which will segue into a deltaH, delta S, and delta G calculation.

Honors: we carefully walked through all of the Le Chatelier and kinetic possibilities for chemical and solution/phase equilibrium problems.
In G period, we defined the equilibrium constant expression, Keq, and discussed its meaning.

Reg: we did a few more practice Le Chatelier problems and then went on to the definition and meaning of the equilibrium constant, Keq, emphasizing that solids and liquids are NOT included in the expression because their concentrations do not change.

AP: we continued to do electrolytic cells. We discussed electroplating and then we explained how to determine the anode and cathode reactions for a given electrolysis and also the minimum battery voltage required to drive such a reaction. We discussed the electrolysis of molten NaCl, aqueous NaCl ("brine"), and water.
As a point of interest only, we looked at the kinetic vs. thermodynamic competition that occurs when aqueous NaCl is electrolyzed.
We then did a quantitative electrolysis calculation. We determined the number of moles of Cu plated via electrolysis given a certain electric current, a time, and a way to calculate the moles of electrons per mol of reaction. We'll do another of those on Monday and then fuel cells will close out our ultimate unit.
Do A LOT of the electrochem problems this weekend!

We're gonna have a good class tomorrow because you're good enough, your smart enough, and gosh-darnit, people like you.
(only G period is going to "get" this)
http://snltranscripts.jt.org/91/91asmalley.phtml

AP: we explained qualitatively via Le Chatelier and quantitatively via Nernst how varying the concentrations in a voltaic cell can either drive the reaction towards the products (increasing E cell) or drive the reaction towards the reactants (decreasing E cell).

We then did several concentration cell problems, one involving a pH meter in which the Ecell is related to the hydronium ion concentration. The other concentrations cells were used to determine the Ksp of sparingly soluble salts.
We then just began to discuss electroLYTIC cells.

Honors: we got into Le Chatelier and kinetic explanations of equilibrium shifts. Be careful with the addition of any solid or liquid substances OR increase in surface area of any solid or liquid substances: solids and liquids generally do not cause a shift in equilibrium; they just increase forward and reverse rates equally.

Regents: we did several Le Chatelier equilibrium problems that covered every possible type of stress on every type of chemical or solution equilibrium. We talked about the "common ion" effect by applying Le Chatelier's principle. We will do one or two more of these problems tomorrow and then we move on to finish the unit.

Honors: we began the most important topic of the remainder of the year: Le Chatelier's Principle as applied to chemical equilibrium. We covered the proper arrow labelling, exoHOT and endoCOOL, and listing the total number of moles of gas on each side of the chemical equation.
We then invoked the three Le Chat questions: 1. What is the stress? 2. What is the opposite or reverse of the stress? and 3. Which direction/shift (towards products or reactants) will cause the opposite or reverse of the stress to occur?
We applied this principle to several stresses on the reversible reaction of nitrogen with hydrogen to form ammonia.
We will continue this example, tomorrow.

Regents: we began the most important topic of the remainder of the year: Le Chatelier's Principle as applied to chemical equilibrium. We covered the proper arrow labelling, exoHOT and endoCOOL, and listing the total number of moles of gas on each side of the chemical equation.
We then invoked the three Le Chat questions: 1. What is the stress? 2. What is the opposite or reverse of the stress? and 3. Which direction/shift (towards products or reactants) will cause the opposite or reverse of the stress to occur?
We applied this principle to several stresses on the reversible reaction of nitrogen with hydrogen to form ammonia.
We started another example and will continue with it tomorrow.
Organic Test Average: 79

AP: we backtracked a bit and showed how the units work and cancel in the Eo =(RT/nF) lnK equation . We then did some qualitative and quantitative redox predictions using the table of standard reduction potentials. We used a shortcut: connect the two reactant particles; if the connecting line slopes down, the reaction is spontaneous under standard conditions and if the connecting line has a positive (uphill) slope, the reaction is not spontaneous under standard conditions.
We then began to look at "concentration cells" in which the anode and cathode are the same metal and the solutions are made from the same salt; the potential difference is caused solely by the difference in concentration of the solutions between the cells. The pH meter is a concentration cell, which we'll discuss more tomorrow.

Honors: Organic Naming/Drawing Test.

Regents: Organic Naming/Drawing Test.

AP: we related the maximum amount of electrical work that can be derived from an electrochemical-voltaic cell, wmax, to -deltaGo to Eo cell to the equilibrium constant, Keq, of the reaction that occurs in the cell.
We then used the Nernst equation to determine Ecell, NOT Eo cell, under non-standard conditions.

Welcome back all. It's tough getting back after such an extended vacation but we must hit the ground running.
Honors: we covered naming and drawing of most of the important types of organic compounds based on their functional groups. We also focused on isomers and showing which different types of organic compounds are most easily related via isomerism.
Whether or not we reviewed a particular detail in class or at extra help, tomorrow's test will cover the whole vacation assignment including the notes, worksheets, modules, and text EXCEPT for questions regarding esters, amides, and also types of organic reactions.

Regents: we covered naming and drawing of most of the important types of organic compounds based on their functional groups. We also focused on isomers and showing which different types of organic compounds are most easily related via isomerism.
Whether or not we reviewed a particular detail in class or at extra help, tomorrow's test will cover the whole vacation assignment including the notes, worksheets, modules, and text EXCEPT for questions regarding esters, amides, and also types of organic reactions. Some of you were clearly unprepared for today's review, which means that, if you do not want to fail after your negligence, you should be studying/writing/drawing nonstop from now until test-time tomorrow. Others, who studied and put in the requisite time over the break will find tomorrow's exam relatively easy.

AP: we looked at SHE, the standard hydrogen electrode (half cell) as the reference point (0.00V) for all other standard half-cells.
We can the determine the potential difference between any two standard half cells and relate that difference to the ease of reduction or oxidation of each half cell.
We discussed oxidizing and reducing AGENTS and how they relate to the overall redox reaction/equation.
We will related Eo to deltaGo and K and look at various non-standard cell questions.

Thanks to a particularly astute Honors student, three misprints from the vacation assignment have been corrected and posted on our now up-and-running website.
Namely, the corrections are:
1. In the "Alkenes and Alkynes" Learning Module, Slide 7:
The slide had a misprint. The alkyne, 2-pentyne, should not have magically changed into an alkene. Check the updated file for the correction.
2. Orange review book answers: p 162 #32; the structural formula for 2-methyl 3-ethyl hexane was cut off or misprinted; I correctly reconfigured the structure and re-posted the file.
3. (Friday afternoon) In the "Aldehydes and Ketones" Learning Module, Slides 14 and 15:
Questions 14A and 14B do NOT coincide with their answers on slide 15 so I changed the questions to:
Now, they match with their corresponding answers on slide 15. The file has been updated.
Done, done, and done. If you have completed the assignment early, good for you; make sure that you have questions ready on Monday. That will be the review day for this assignment before our test on Tuesday.

Thanks to the students who alerted me to the current website blackout. I copied the relevant files over to Edline so just go there, log in, and find the vacation assignment files in the "assignments" section or on the "calendar". Chemblog is still up so I will post any updates when necessary. I hope that you had a Happy Easter and that you continue to enjoy and revel in your vacation (while allotting nice chunks of time for chem).

As promised, I posted the answers to all of the section assessment questions from the text Ch.22 and Ch. 23-1 through 23-3. You should do at least one text section, learning module, and worksheet per day.
Though there is some information in the reading about organic REACTION TYPES (e.g. substitution, oxidation, fermentation, etc.) , you will NOT be tested on reaction types just after the break. The focus of this assignment is learning how to NAME compounds according to the IUPAC system and also learning how to write the molecular, condensed, and structural formulas of organic compounds and isomers. Your knowledge of names and formulas will be tested just after the break.
The way to learn the names and formulas is to WRITE them out and/or make flashcards and follow these time-tested mnemonics:
the first four prefixes of each homologous series are meth- , eth- , prop- , and but-
so, just remember Mary, Eats, Peanut, Butter...
for alcohols, the functional group is R-OH, so remember to see al-COH-ol ( the "R" represents a hydrocarbon side chain leading up to the functional group)
for ethers, which have the functional group R-O-R', remember e(i)ther OR .
for aldehydes, which are R-CHO, remember "CHO mama is an aldehyde", which is patently silly and ridiculous but for some crazy reason, the mnemonic works!
I don't have a mnemonic for ketones, but maybe you can send me one.
for esters, which are RCOOR', remember that Aunt Ester drinks COORS.
for acids, which are RCOOH, remember that acids are COOH-(L) daddy-oh.
for amiNes, remember that amines have N in them and they look like ammonia.
for alkanes, alkenes, and alkynes, remember that they have single, double (i.e. TWO "e"s in alkene) , and tr-y-ple bonds, respectively; plus, a, e, and y are in alphabetical order.
This info should make the assignment more manageable.
Do not even wait until next week to start this assignment; learning to name organic compounds takes time and practice.

The link to the AP exam question part of the assignment is properly associated, now. ALSO, don't forget your individual project KARMA assignments.
I will post the questions and solutions to all of the past AP exam homework questions so that you can check your answers and/or methods; that should help you with the vacation assignment.
Note: You will be the new guinea pigs for the slight format change in the 2007 AP Chem exam. By the way, the next major AP Chem overhaul will occur in 2010 and will actually ALTER the curriculum! I can see it now: no Bonding unit (too hard), no stoichiometry (too much math!), no quantum (too "physics-y").
The new exam FORMAT, which tests the same content as has been tested since MO theory (too close to reality) was dropped, will weight the multiple choice Part I and the written response Part II (A and B) at 50% each towards your final score. The weighting HAD been 45% of the multiple choice score and 55% of the written response score. No big deal and maybe even good news for us because I have never heard any of my former students complain or worry about the multiple choice part of the exam after they sat for the test. That section has 75 questions in 90 minutes and almost all of my former students completed that section on time whereas most students don't make it through two-thirds of the questions. Obviously, we will be practicing MC test-taking skills when you all get back. Those few who have made it to the "5-Steps" review sessions already know the importance of rounding, estimation, and selectivity on the multiple-choice section.

The "big" change is that you will now have only six part II questions. Formerly, there were eight total part II questions from which students would HAVE to answer questions 1,4,5, and 6 but would choose to answer either question 2 or 3 and then answer either question 7 or 8, for a total of six part II questions.
Since the collegeboard has taken away choice in part II, you can expect the questions to cover more than one topic per multi-part question. Multiple topics per question is NOT NEW; however, now there will just be probably two more questions that contain multiple topics. So, for example, your question 6 may start with periodic trends and then go on to bonding; question 2 may start with kinetics and go on to stoichiometry and colligative properties. Big deal.

On your vacation assignment, you will be answering ALL of the questions anyway. MAKE SURE that you do whatever questions you can IN THE ALLOTTED time. Then, if you have not already done so, go on to finish the test. Practicing WITH time pressure is crazy crucial at this point. Even at this point, question 4 (descriptive chem) should take you NO MORE than eight minutes (on a slow day!). Oh yes, starting this year, all equations MUST be balanced; that is also not a bad thing since balancing the equation is a self-check on the feasibility of your predicted products.

Before you start the assignment, you should look over your course notes and past exams for an hour or so. You should begin these tests with at least a partially refreshed and updated memory.

Bon chance, all.

AP: we had our Thermo exam with the crazy numbers; suffice is to say, this test came with safeguards (i.e. you had to write out the general equations and then plug in the data) that you won't get on the AP exam. Fortunately, you abided by the directions and were able to deal with the wide variety of questions on the test. So far, the results are very good as is our start of this last, brief quarter together.
Gradually do Project KARMA over the break and really learn for yourself whatever wasn't clear during a test this year. Do NOT just try to make corrections from sketchy memory. Revisit your notes, tutorials, and the text. Then, try to answer the questions.
Email me if you get stuck on a problem.
I'll post the three AP Part II exams later tonight. You've already been doing part II questions over the past few weeks so this should be more of the same. Again, if you have trouble, email me and I'll point you in the right direction or clarify a given question.

Regents:
The vacation assignment is online; email me if you have a question about naming any of the types of organic compounds.
When you return, we will briefly review your assignment for a day; then, you will be tested on naming molecules of each type of organic compound assigned.
Then, we return to the all-important Le Chatelier's Principle.
Quiz today?: the majority needs to study more; A LOT more.

Honors: we had our first kinetics and enthalpy/energy changes exam. I will grade those over the vacation.
The vacation assignment is online; email me if you have a question about naming any of the types of organic compounds.
When you return, we will briefly review your assignment for a day; then, you will be tested on naming molecules of each type of organic compound assigned.

AP: we wrapped up the Thermo unit with a discussion of each of the thermo problem types. We then discussed electrical potential and half-cells. We also discussed free energy and work. We discussed the advantage of using electrochemical cells to avoid thermal energy loss to the surroundings.
We will continue with that unit after the test tomorrow, briefly. We will also do a quick thermo lab. The test will go till about 9AM and will have proportionately fewer questions. There will be only Thermodynamics questions on this unit test.

Honors: we discussed each type of equilibrium and set up for the upcoming most important concept of the rest of the course: Le Chatelier's Principle. Sadly, we will have to wait until after the break to explain that. We have the first test of the last quarter tomorrow: this will cover the notes from heating and cooling curves through the notes on kinetics and potential energy/ enthalpy diagrams.

Regents: we discussed each type of equilibrium and the various terms associated with each.
We will have a brief quiz tomorrow on enthalpy diagrams, heats of reaction, and heating/cooling curves and then we will continue with our equilibrium unit.