Chemblog!

Honors: we highlighted the differences between nuclear fission and nuclear fusion; note that, though these are opposite processes, both processes involve the conversion of some nuclear mass to energy, which is why both processes are highly exothermic/energy-releasing. Tomorrow, we have our nuclear physics unit test.
Friday, we will do our colligative properties/ice cream lab. Make sure that you bring gloves and your winter-wear to class. Bring rain-gear in case of inclement weather.

Regents: we did a few more molarity problems involving mass of solute and volume of solution. We then discussed how to dilute a solution to a particular molarity by adding a certain amount of solvent. We derived the "solution dilution" formula, which has the mnemonic "voom- voom"; then, we applied the formula to a couple of solution dilution problems.
Reinforce this information by doing the assigned homework in chapter 16 of the text.

Friday, we will do our colligative properties/ice cream lab. Make sure that you bring any "blend-ins" that you want in your ice cream; also bring gloves and your winter-wear to class. Bring rain-gear in case of inclement weather.

AP: we finished our polyprotic acid problems. We then started on the more qualitative part of the unit by explaining the relative strengths of a series of acids by weighing their relative bond polarities and bond strengths.

I hope that you all have recharged your batteries and are ready to excel for the rest of the second half.

AP: today we covered weak bases and polyprotic acids. The main things to watch out for are:
when you solve for "x" in a weak base problem, you are solving for the HYDROXIDE concentration so be careful when the question asks you for the pH, not the pOH.
when you do the second ionization step in a polyprotic acid calculation, don't forget that your INITIAL concentrations will NOT be zero for the H+ and for the anion, HA-, that resulted from the first step!
Plenty of practice files are up now to help you practice for Friday's test.

Honors: we covered the best of nuclear in a day. I will tie up some loose ends tomorrow. I was impressed that you all seemed to be on top of what I was discussing with you. Cheers.

Regents: we revisited some mole-mole and mole-liter and mole-mass calculations and then went on to our next subtopic: Solutions. We will dig into more of those problems tomorrow.

Honors: I just tallied the results of the Math of Chem exam and there is a large chasm between the D and G period class averages.
Class average-
D: 90 (time to celebrate! There were three 100's and a 99!)
G: 81 (what up G? There were two 100's but this class average was dragged down by about 7 clearly unprepared students who failed badly; there were very few people at extra help before this test.)

Most of you wrote lucid and easy to follow answers: you used proper formulas, units with labeled/identified substances, attention to significant figures, and unit cancellation.
In your notes, ALL of the test problem types had been done multiple times with complete annotation and warnings about common errors. That is how math of chem works: from the class and hw examples, I just have to change the substances and the amounts used and I have a complete and thorough exam. As some of you have proven, you can get a 100 on any of these math of chem tests via practice/repetition.
Please prove that to yourself on your next stoichiometry test.

I found a good site for some quick and easy rate law practice. Try it when you have ten minutes to spare. It's fun?
Click on "New Problem" to get the questions started.
Rate Law Practice

Question 68 on the take-home test has an error; namely, there is no listed correct answer to the question.

Consider the same answer choices but CHANGE question 68 to read:
"Which of the following is a linear non-polar molecule that has a total of 5 non-polar covalent bonds?"

Nobody had emailed me regarding that error. There are four days of vacation left. If you think that, in one or two days, you can do the test WITH work shown for EACH question, you are kidding yourself and gambling with your average during this VERY short third quarter.
To those of you who haven't started the assignment: Are you just going to copy the work from someone and learn NOTHING? That strategy will fail you in the short term and in the long term, as you will discover.

I posted part I of your Winter Break Assignment. It is a take-home test worth 100 points towards your quarterly average. On each question, SHOW YOUR WORK/REASONING, otherwise you will not receive credit. Even if the work is an illustration or a definition, write it out. MAKE SURE that your work is legible and neat; in addition to making notes on the exam, you probably should do your work on separate paper so that you have sufficient room.

The exam is due on the Wednesday of the week of your return to school (whether you went to Europe or not). You certainly will have plenty of time to complete it, given the longest winter break ever. When you return to school, we will only have time for a couple more tests this quarter so make sure that you do this assignment correctly.

Honors: we did several permutations of molarity problems starting with some combination of grams, moles, liters, molarity, and a specific solute. We began to discuss solution dilution and the formula involved.

Regents: we began stoichiometry using balanced chemical equations. We solved "mole to mole" problems and then did some mole to gram and mole to liter problems for practice.

AP: we learned to THINK about equilibrium calculations by analyzing the RELATIVE quantity of weak acid that is ionized vs. un-ionized, which tells us when we can neglect the amount of acid that is lost via ionization RELATIVE to the initial amount of acid.
All of that boils down to the 5% rule, which let's us know whether we can "neglect x" RELATIVE to the initial acid concentration.
We will do the same thing for weak bases (mostly organic AMINES).
We also showed that, as a weak acid is more and more dilute, its percent ionization increases YET, ironically, the pH of its solution gets closer to 7 (because, with enough water, all solutions eventually dilute to a pH of 7, at 298K).
I can't post the AP exam question until late tonight so it will not be due tomorrow. You can download it then.

There are two parts to the assignment with TWO different respective due dates.
(1) The first part will add a full 15 points onto your last exam, if done perfectly i.e. immaculately neat and legible, every "i" dotted, every word spelled perfectly, no grammatical atrocities (not a SINGLE student uses the idiom "there is" vs. "there are" correctly, not ONE of you!), and all necessary and sufficient information.
If the corrections are not complete and perfect, your score will remain unchanged.
I will post a question by question list of necessary information that should be included for each answer. Any doubts about your explanation must be emailed to me over the break.
This part is due, in class, the day of your return to school.

(2) Since we are over one week behind schedule, we must compensate by doing the Nuclear Physics (that's right, it's physics) unit over the break.
Carefully PERUSE and highlight the Orange Review Book Topic 12: Nuclear "Chemistry" (it's physics, really). Do all problems in that unit (from pages 175 through 188). I WILL post all of the answers so just check them.
I will also post a tutorial (same as the type from the last break) that I want you to write out, solve, and hand in (just as you did last time).
This part of the assignment is due by Wednesday, the week of your return to school (there will be a test that Thursday ON Nuclear Chem/Physics).
I will spend the Monday that we return to school on Nuclear but that is all. We have to get back on pace.

We started our very abbreviated week (which may be further truncated by snow on Wednesday: good for vacation; bad for cramming all of the required material in an ever-shortening year).

AP: we did problems involving predicting the direction of a Bronsted acid- base reaction as it goes towards the equilibrium state. We took into account the relative strengths of the conjugate acids and conjugate bases in the reaction and then made the logical prediction that the reaction would always proceed from "strong" to "weak", i.e. higher Ka and Kb value side to the lower Ka and Kb value side.
We also proved that, given the Ka of an acid, the Kb of the acid's conjugate base is Kw/Ka. We showed this from combining the two ionization equations to show that they add up to the ionization of water equation, which has the K = 10^-14 at 298 K.
By the same logic, given the Kb of a base, the Ka of the base's conjugate acid is Kw/Kb.

Tomorrow's lesson is REEE-diculously important. We will be doing equilibrium concentration calculations for weak acids and bases. Remember, since these substances do NOT ionize 100% at equilibrium, you will need to set up an ICE table (for now) to calculate the final equilibrium concentration of H+ from which you will also know the pH. Eventually, you will see the pattern and this will be a 5 SECOND PROBLEM (no DOUBT).

Honors: we revisited and summarized stoichiometry problems of each type and then we moved on to the next Math of Chem topic: Molarity and the "strength"/concentrations of solutions.
So far, the first math of chem tests look generally GREAT... not just good but GREAT. I am pleasantly surprised how well some of you followed the methods used in class, which automatically help you to avoid errors; in turn, there are two 100's and several high 90's already. That is not only without ANY grade inflation, curve, boost but also with extreme prejudice and scrutiny for the slightest errors that I warned about regarding units, formulas, and sig figs. There is hope!

Regents: we had our first Math of Chem exam. Results pending...
Now the results are in:
Class AVERAGE: 67...absolutely PATHETIC! Keep up with the lack of extra help (only THREE people all week! almost NO questions from anybody at anytime even though everything on this test could NOT have been more CLEARLY spelled out!), ignoring the homework, not taking notes, not downloading the notes and you will get what you are preparing for: summer school. That is not a threat, just a sad fact. The Regents exam is NOT EASIER than the exams you have been taking. The next test will involve similar math skills and an even greater variety of problems. Most of you will fail that test also if you do not drastically deviate from your poor work ethic. I can't possibly be more available to answer your questions and I am getting very little in return from most of you. How about putting in some effort to make my effort worthwhile?

Honors: we had our first full Math O' Chem exam. This one shouldn't take me as long to grade and I'm hoping for a comeback although there were VERY FEW of you at extra help the past two days (last year, there was standing room only before most tests).

The last test, which I warned you about weeks ahead of time, was a disaster that should NOT ever be caused by true Honors students (especially those with such "excellent" averages in every other subject). The fact that all of you have A's in English yet almost all of you do NOT know the basic difference in meaning between the words "is" and "has" makes me very curious and suspicious. For example, the fact that almost all of you wrote the non sequitur "water IS a hydrogen-bonding attraction" speaks volumes about the lack of preparation and understanding of basic English. Remember, you can't drink an attraction but you can drink water.
I should not reward such obvious negligence on the part of most students but I will relent this one time because I cannot have you end the most important unit in chemistry without knowing this material. Should such a mass lack of preparation and flouting of basic test-taking practices ever happen again, I will not give anyone a second chance to improve his/her grade and you will just have to accept the consequences.
I will put up directions on how to correct this test and talk about this with you next week. You can improve your score by up to 15 points. As some have already done in the past, do NOT add insult to injury by handing in faulty corrections; how could anyone possibly hand in "corrections" that are rife with errors when you can just ASK ME to show you how to answer the questions?!! I'll tell you how: wanton ignorance, laziness, and negligence. You can't have those qualities and get an A in THIS CLASS.

Regents: we finished the three parts of the "magic triangle" that quickly gets us from grams to moles to molecules to moles to liters of gas at STP.
Study hard for Monday's first Math of Chem exam. The info that we covered in class:
1. Equation Balancing and the meaning of chemical equations (coefficients, etc.)
2. Types of Chemical Reactions
3. The Mole and Calculation of Molar Mass: Gram-Atomic Mass, Gram-Molecular Mass, and Gram-Formula Mass
4. Percent Composition of ANY compound or hydrate, given the formula.
5. Grams of a given element from a compound, given the percent composition or molecular formula
6. Empirical to Molecular Formula, given the empirical formula and the gram-molecular mass of the compound.
7. "Magic Triangle Conversions" of any type.

You will NOT be tested on some of the things from the notes, that is, what we did NOT cover in class:
a. determining an empirical formula from percent composition (we only did the reverse calculation)
b. using balanced chemical equations to determine moles of reactants and products that are actually consumed and formed- that will be on a subsequent test.
Monday is Day 1 so I will be in Room 229 at about 7:30 AM for any last minute questions.
ONLY TWO Regents students were at extra help on Friday; are you ready for the test on Monday?

AP: we discussed Bronsted acids and bases in terms of conjugate pairs and their relative strengths. We defined pH and
p(Anything) and applied the term in calculations. We also started to become Varsity Chem experts at estimating pH from a glance at the [H+] and noting the multiplier and the exponent.
Good times.
Next week, we have three days to finish the unit so I will be faster than an auctioneer at times. I will post our "organic" winter break assignment, which requires development of expertise in naming orgo compounds and recognizing organic reaction types, with a little metal ligand refresher thrown in for good measure. Not too bad, overall.

I've noticed that almost NONE of you has a watch. This weekend, go down to your local whatevermart and get one; they are about $6 with a stopwatch function included. You'll find that you'll be able to pace yourself during tests and not be so shocked when the bell rings. The fact that you do not have one after you have spent too much time on question after question on test after test is further proof of the lack of effort to improve and grow.
I know that people rely on cellphones to keep time nowadays but you can't use those during a test.
So, during the next test, I will be checking to see, among the bracelets and bangles and lanyards and tatoos, whether you have a timepiece on your wrist.
Watches: they help you keep track of time; the more you know.

The file posted yesterday (020707) entitled, "Quiz that you could have had today! Allow only 12 minutes! " has an error on question 3d.

The equation should read MgCO3 (s) --> MgO (s) + CO2 (g)

The equation in the file has O2 as a product and no C, which is impossible because there is C in the carbonate anion on the reactant side.
Please make the correction because I cannot re-upload the file until late tonight.
Thank you and good luck tomorrow. There are not many tests this quarter due to the many, many vacation days so each test will weigh heavily towards your third quarter average.
p.s. DO NOT COME INTO CLASS WITHOUT A SCIENTIFIC CALCULATOR TOMORROW OR YOU WILL HAVE TO DO THE TEST WITH AN ABACUS OR A SLIDE-RULER (good luck with all that).

Regents: we did a few more percent composition problems and then did several "magic triangle" mass to mole to number of molecules problems. We will continue with those and go into stoichiometry using chemical reactions, tomorrow.
There will be plenty of practice problems to do over the weekend in order for you to prepare for Monday's first Math of Chem exam.

Honors: we covered mole-mole, mass-mass, volume-volume, mass-volume, and molecule-molecule problems. Tomorrow's exam will cover up to and including the notes on volume-volume problems.
This quarter is severely truncated by winter break so the value of each test is magnified. Most of you were unprepared for the last test and, as a result, did poorly. You do not have that many opportunities to overcompensate for that last exam. Therefore, make sure that you are expert at each problem type before you walk into the exam room tomorrow.

AP: we took the first of many equilibrium tests, which will all involve ICE tables (and eventually the very cool SRFC "surface" table!) so, if you know how to work them already (especially the "C"= change line), that bodes well for the future.
Tomorrow, we will put a HEAVY dent into the acid-base unit

AP: we completed our lengthy Le Chatelier explanation with a solid, anchor-example for pressure increase or decrease stresses. We then covered the remaining stresses and their effects on aqueous and gaseous systems.
We then briefly introduced our new unit: Acids and Bases. We will cover a lot of that unit by Friday so that you can do something with that info over the weekend.

Honors: we reviewed gas density at STP to molecular mass problems and then did the reverse process of taking any given gaseous substance and determined its density at STP.

We then began the heart of stoichiometry: taking balanced chemical equations and determining the number of moles, grams, liters, or molecules (or atoms or formula units) of each reactant and product. We will do each type of stoichiometry problem over the next few days.
Friday is our first real Math of Chem test. The questions will cover everything from the beginning of the unit's notes up to what is covered on Thursday (I'll announce the cutoff in class).
It is an indisputable fact that most of you did NOT study for the last exam. If you think that you did study, one look at your test will show you just how inadequate your preparation was. Even those who did study continue to throw test-taking advice away: they fall into the same old pattern of writing long-winded, irrelevant statements instead of drawing and labeling a picture of what is actually happening and then briefly describing and referring to the picture.
Had you written out the answers to the questions that you knew were going to be asked and, BEFORE THE TEST, checked with me that your answers were sufficient, you would not have failed. There is nothing new to this criticism. I have been saying the same thing since September. It is sad that many of you are unwilling to change or grow.

I have already warned you about the mistakes that former classes have made on this upcoming Math of Chem test. The only way to master this unit is to properly and carefully write out many examples of each type of problem so that you can recognize what to do and where to begin for each type of question. If you do not give yourself adequate experience with each problem type, you will come up with non-sequitur answers that earn you no credit.

Regents: we did more percent composition problems including the special case of determining the percent mass of water in a hydrated salt.

We then further developed the "Magic Triangle", which will be at the heart of the rest of the problems for this unit. We will work more with this fast calculation tool tomorrow. We have a test on MONDAY so you should get to extra help tomorrow and Friday (at extra help, most of the Honors students' questions will be relevant to what you need to know).

UPDATE: the Equilibrium Practice Tests that were posted on 020507 contained several ERRORS in the answer key; thanks to DM, we corrected the answer key at extra help; I just uploaded the corrected file which is still linked where it was originally.

I wrote this last year.
I think that this will be a good Le Chatelier review of the temperature, pressure, and inert substance stresses: Naturally, accompanying pictures and diagrams would greatly clarify and enhance the explanation and, perhaps, make the written part more concise.

inc P (or dec V), at constant T and n, is the same as increasing the concentrations of any gases. This occurs because, if you increase the external pressure on a system of gas(es) the piston of the container will be forced down because nothing initially occurs to the collision frequency of the gases (i.e. the internal pressure is initially the same). So there is a net force pushing the piston down which decreases the container volume which gradually increases the collision frequency of the gas particles with the container (the gas particles have the same average KE but they are moving in a smaller volume, which causes more frequent collisions). So, there is an increase in collision frequency and therefore a greater forward and reverse reaction rate (due to the greater number of molecules available for collision per unit of volume = inc concentration); an inc in conc of all gases on the side with MORE GASEOUS molecules causes a disproportionately greater inc in that side's reaction rate so there is a NET shift toward the side with FEWER molecules as the new equilibrium is reached.

dec P (or inc V), at constant n and T, is the same as a decrease in concentration (see above reasons) of all gases so there is a decrease in collision frequency and therefore a decreased forward and reverse reaction rate (due to the lower number of molecules available for collision per unit of volume = dec concentration); so, a dec in conc of all molecules causes a disproportionately greater decrease in reaction rate on the side with more GASEOUS molecules; thus, there is a NET shift towards the side with more molecules as the new equilibrium is reached.

inc T speeds up both forward and reverse reaction rates because there is increased collision frequency and a greater fraction of effective collisions (due to the higher T = higher avg. KE of the molecules in the system so a greater fraction of molecules meet or exceed the activation energy requirement for reaction) but there will be a disproportionately larger increase in the NET "energy consuming", endothermic, direction.

dec T slows down forward and reverse reaction rates because there is decreased collision frequency and a decreased fraction of effective collisions due to the lower T = lower avg. KE of the molecules in the system) but there is disproportionately greater decrease in the endothermic (NET energy REQUIRING) direction so that there is a net shift to the EXOTHERMIC direction.

Of course, giving specific examples with made up numbers for the forward and reverse rates is the BEST thing that you can do because you can then quantitatively show towards which side (reactants or products) a NET shift occurs as the system proceeds towards the new equilibrium.

more stresses...
addition of a catalyst: a catalyst affects the orientation of the colliding reactant(s) by temporarily binding the reactant(s) in such a way that bonds are strained (and thus require less energy to break) or inter-particle attractions are weakened (so the less energy is needed to overcome the attractions); thus, a catalyst lowers the activation energy for both the forward and reverse reaction. Catalysts lower the activation energy of both forward and reverse reactions EQUALLY. Therefore, though both the forward and reverse reaction rates increase (because, at the same temperature, a greater fraction of reactant particles have enough kinetic energy for an effective collision due to the activation energy- lowering effect of the catalyst), there is NO NET shift towards the reactants or products because both rates are increased EQUALLY.

addition of an INERT gas:
addition of any non-reacting substance will NOT affect the equilibrium concentrations of the gases (or anything) as long as the system is at CONSTANT VOLUME!!! This is because, at constant volume, even if you add many many moles of an inert gas, the PARTIAL PRESSURES and, thus, the CONCENTRATIONS of the reactant and product gases remain CONSTANT because the number of MOLES per LITER of the reactant gases is NOT CHANGING as the inert gas is added. The number of effective collisions per second of both reactant and product particles remains the same because the inert gas both interferes with and CAUSES collisions to the SAME extent so that there is NO NET change in the effective collision rate.
BUT, if an inert gas is added at constant TOTAL pressure i.e. the VOLUME expands, the effect is to LOWER the PARTIAL PRESSURES/concentrations of the reactant and product gases (initially). So, just treat that situation as an INCREASED VOLUME or DECREASED PRESSURE stress. Thus, the equilibrium will shift to the side with a greater number of moles of gaseous molecules (in the balanced equation) due to the decrease in BOTH the forward and reverse reaction rates but a disproportionately greater decrease in the reaction involving the side with a greater number of moles of gaseous molecules.

Regents: we applied the definition of the word "percent", which is (part divided by whole) times 100%, to percent composition (by mass) of each element in a given compound.
We then began our shortcut path to all mole to gram to molecule calculations via the "Magic Triangle", which simply relates how the number of moles of a given substance can be converted to the number of grams, molecules/ion/or atoms, or liters of gas of the given substance.
We will further develop that tomorrow.

Honors: we completed forwards AND backwards, a molecular formula to empirical formula to percent composition to empirical formula to molecular formula problem. As you practice these problems, you should double-check your work forwards and backwards until you know how to do these problems no matter what the starting point.
We then talked about Avogadro and the MOLAR VOLUME (number of LITERS per MOLE) of ANY gaseous substance (behaving ideally) at STP, which is 22.4 liters per mole.
We then completed the final vertex of the magic triangle which converts moles of a gaseous substance at STP to liters and vice-versa.

AP: we qualitatively explained Le Chatelier's Principle and then explained the much more detailed kinetics/particle-level explanation that OBVIATES the need for any kind of human conceptual shortcut principle; that is, we explained what is ACTUALLY occurring when a given stress is applied to a system that is already AT EQUILIBRIUM. Today, we covered (1) the stresses of inc/dec concentration or partial pressure of reactants or products and (2) inc/dec volume or total pressure on the system. Tomorrow, we will cover the stresses of adding an inert gas at constant volume (no effect) or at constant pressure (dilution/increasing volume effect); we will also cover the "stress" of adding a catalyst and the NON-EFFECT of adding ANY SOLIDS or LIQUIDS (one exception, though) or INC/DEC SURFACE AREA of a liquid or solid.

AP: we did a couple of heterogeneous equilibrium problems involving solids and gases. We learned that the AMOUNT of solids or liquids in no way shape or form affects the equilibrium concentrations or partial pressure of any gaseous reactants or products. Also, since ICE tables only contain CONCENTRATIONS, just cross out the entire column involving any solid or liquid.
HOWEVER, from the changes in concentrations of any aq or gaseous reactant or product and the COEFFICIENTS from the balanced equation, you can calculate the loss or gain in MOLES of any solid or liquid reactant or product.

Tomorrow, we will EXPLAIN, DRAW, and, complete Le Chatelier's Principle at the PARTICLE level in terms of stresses and EFFECTIVE COLLISIONS PER SECOND.
Then, we begin our new unit: Acids and Bases!

Honors: we did some of the more difficult % composition to empirical formula problems; these problems have empirical formulas that take an extra step to decipher. For example, if after dividing the number of moles of atoms of each element in your compound by the lower (est) number of moles of one of the elements, you then get a NON-integer ratio, you must do one more step. So, if you get, for example, C 1.00 H 2.666 , then change the numbers to fractions to see what number is in the denominator of the fraction...i.e. C 1 H 8/3 (because 2.666 = 2 and 2/3 = 8/3) ; so, multiply both subscripts by 3 in order to eliminate the fraction and you get C3H8, which is the correct empirical formula!

We then learned about the SCALING FACTOR which is the ratio of the gram-molecular mass (of the molecule) to the EMPIRICAL formula mass that you calculated from the percent composition. Once you get the scaling factor, multiply the subscripts of the empirical formula by the scaling factor, which will net you the actual molecular formula.

Regents: we reviewed the concept of moles and the atomic mass scale; then we got much more practical and calculated the molar masses of atomic, molecular, and ionic substances. These masses are called gram-atomic mass, gram-molecular mass, and gram-formula mass, respectively. Just set up a table to keep track of each element and the number of moles of each in a given compound and you will be able to methodically calculate the molar mass of any substance.
Tomorrow, I will post worksheets regarding these calculations. Bring your Orange Review Books to class this week; we will be doing problems from that book during class.

Honors: we did several percent composition problems: percent of each element in a compound and then percent of water in a hydrated salt (a "hydrate").
We then did the REVERSE process of going from percent composition to EMPIRICAL formula of a compound. Practice these problems from the worksheets over the weekend.

Regents: we finished how to recognize five common reaction types: synthesis, decomposition, single replacement, double replacement, and combustion. We balanced several equations and learned some time-savers and strategies on how to balance some of the tougher problems involving combustion and double replacement.
Practice the equation balancing worksheets this weekend.

AP: we learned about Q, the reaction quotient, and how to compare its value to K in order to predict whether a reaction will shift towards making more products or reactants as it proceeds towards equilibrium.

We then learned the MAIN bookkeeping method that we will employ for the rest of the course: the ICE TABLE!
I will put up the Ti-83 solver tutorial for any quadratics that we need to solve quickly (this will be much faster than getting the equation into proper quadratic form); even better, a graphical solution will be easier to do so I will put up a tutorial on that also.

AP: explained how solid-gas-and/or liquid heterogeneous equilibrium constants are SOLELY determined by the partial pressures of any gases in the equilibrium expression and that, even if you add tons more of the solids or liquid, there will be NO EFFECT on the equilibrium concentrations/partial pressures of the gases because the solids and liquids cannot change in CONCENTRATION, no matter what their amounts.
We manipulated equilibrium constants by halving or doubling or tripling the coefficients in a given reaction to see that the equilibrium constants would be taken to the half, second, or third power, respectively.
We also showed that, when two or more equations are added together, the net equation's equilibrium constant is the PRODUCT of the equilibrium constants of the added reactions.
Tomorrow, we begin a technique for solving equilibrium problems that we will use every day for the rest of the year.
Next week, I would like to start AP review using our "5 Steps to a 5'' books. I'd like a vote in class tomorrow to designate a day or days on which we can hold these review session.

Regents: Long test today but the average was an 83, so we are back in business. Intermolecular attraction/ Bonding is a big topic on the Regents so it is important that you do reasonably well on this test. I didn't see any real disasters and there were some middle to high 90 grades, so that is a good sign. Still, the day that I start to see better extra help attendance is the day that the class average will go into the 90s.

Honors: we reviewed the magic triangle and did some mass to mole to particle problems. We even did a formula unit to ion problem that involve one more simple step.
We moved on to percent composition, which we will continue tomorrow. Over the weekend, there will be some worksheets and text reading on all of the problem types that we have covered.