Chemblog!

The biggest thoroughbred race of the year takes place half-a-world away in Saudi Arabia this Saturday. Forget about the Kentucky Derby (until next month!); the race tomorrow, broadcast on ABC at 2:30 PM, pits the two greatest horses in the world, 2006 Horse of the Year, "Invasor", against the undefeated, "Discreet Cat". Invasor is so remarkable that he has lost only once (to Discreet Cat, last March at the same track in Arabia) and, unlike most horses, he does not get winded after a long race. Discreet Cat is UNDEFEATED and has run some of the fastest races in thoroughbred racing history.
I think that Invasor is going to win but, either way, the race is going to be historic.
So, if you've never seen the "Sport of Kings", tomorrow's race will be a great introduction.

AP: ack! I had a feeling that I gave some misinformation on Thursday. The last problem that we did, the generic Thermo problem, was solved correctly; however, I suggested an alternate way to get delta S of the reaction was to get the individual entropy, S, of each reactant and product via the delta Gf and the delta Hf values. THAT IS NOT POSSIBLE and it goes to the heart of the MAJOR DIFFERENCE between ABSOLUTE entropy, S, and a change in entropy, delta Sf. There is NO such equation as delta Gf = delta Hf - TS (which is what I erroneously suggested to use). There IS only delta Gf = delta Hf - T delta Sf ! The delta Sf values were not given and are not equivalent to the ABSOLUTE entropies of the reactants and products, anyway. If you think about it, for an element, "delta Gf = delta Hf - T delta Sf" is a useless equation because delta Gf and delta Hf are zero for elements in their standard states! Therefore, delta Sf for an element would also be zero even though we know that ABSOLUTE entropy CANNOT be zero for ANY element under any circumstances (except at the ridiculous temperature of zero Kelvin).
Bottom line: solve that type of problem as we did in class and ignore any alternate way (there is none).
Do all of the Thermo worksheets and any additional assigned problems to be posted this weekend.
Here is a link to some college Thermo lectures that you can use for review:
Complete lecture list from Texas A&M General Chem
Entropy Lecture
Free Energy Lecture
Texas A&M Class Website with Notes

Honors: we did another enthalpy diagram, this time for an endothermic reaction. We drew and labeled the nine arrows associated with the regular and catalyzed reaction.
We then discussed and defined equilibrium: phase, solution, and chemical. Juniors, study the relevant notes and do the text reading; come to extra help if you have any questions about this lesson. Look for the vacation assignment to be posted this weekend.

Regents: we completed an enthalpy diagram based on information
from Table I. We labeled each arrow and then did some calculations from the diagram.
We then defined the term "equilibrium".

Those who missed this class, study the relevant notes and do the text reading; come to extra help if you have any questions about this lesson.
Look for the vacation assignment to be posted this weekend.

Honors: NOTE: since the juniors are off tomorrow, I am CHANGING the date of our test to next TUESDAY. So, you have one extra day to practice/prepare. I will be in at about 7:30AM on Friday for extra help and at about 8AM on Monday (on Monday, I will NOT be in Room 229 but rather in Room 237.) I will not be available for extra help after school (for the first time ever) on THIS Friday afternoon but I will be available for extra help after school, as usual, on all other days.
We finished the 5 factors that can alter the rate of chemical reactions; we explained each factor (as you will DEFINITELY do on your next test) in terms of the effect on (1.) collision frequency (2.) kinetic energy/force of collisions with respect to the activation energy barrier (3.) orientation/angle of collision with respect to alignment of molecules for an effective collision. We related each of these terms to the ONE measurement that is 100% SYNONYMOUS with reaction rate: the NUMBER of EFFECTIVE collisions PER SECOND.
We then revisited enthalpy diagrams and labeled each of the relevant quantities or "arrows" on the diagram.
More of that tomorrow and then it is on to the Equilibrium part of the unit.

Regents: we did some quantitative calculations involving enthalpy diagrams. We also labeled the arrows in the enthalpy diagram for an uncatalyzed and a catalyzed reaction. Make sure that you can draw those diagrams and know what each arrow represents. There will likely be a quiz next Tuesday.

AP: we wrapped up the Thermo Unit by doing some problems that relate delta G standard to the equilibrium constant, K, at a given temperature. We also discussed "coupled" reactions, which are so important in biochemistry and in chemical engineering.
We then did a generic problem in which Hess's Law was applied for delta G and for delta H so that delta S of the reaction could be obtained.
Practice all of the worksheet problems and tutorials this weekend so that you are prepared for one of the very few fourth quarter tests.
I will post your vacation assignment: three AP Part II exams and Project KARMA, a comprehensive correction of any past test errors from this year. Project KARMA was THE main reason for the unanimous fives, last year. Without the diligent and meticulous effort applied to that project, last year's class would very likely have had four 5's, some 4's and a FEW 3's (ack!). You will notice that the AP exams that we will take from the end of April through Test Day become SIGNIFICANTLY easier once you have corrected your past errors to the point of full understanding of why you made the error in the first place and of how you can recognize a similar question type and avoid that error in the future.

Honors: we did more thermochemical equations and related those reactions or processes to enthalpy diagrams. We varied the mole quantities and calculated a proportional change in the quantity of heat absorbed or released.
We then discussed two of the five factors that can AFFECT the rate (number of EFFECTIVE COLLISIONS per SECOND) of a chemical reaction. We will finish explain the other factors tomorrow.
Our next exam is on Monday. The vacation assignment will be posted this weekend; you will be have a 100 point test on the assignment on the second day of our return from vacation.

Regents: we calculated the energy released or absorbed for several chemical reactions or physical processes listed on Table I.
We then varied the mole quantities and calculated a proportional change in the quantity of heat absorbed or released.
We then began to define and explain the three types of equilibrium: phase, solution, and chemical.
The vacation assignment will be posted this weekend; you will be have a 100 point test on the assignment on the second day of our return from vacation.

AP: We qualitatively calculated the relative temperature required for a spontaneous process depending on the signs of delta H and delta S for a reaction or process.
we calculated the entropy change for a phase change at the equilibrium temperature by noting that delta G is zero at such a temperature, so negative delta H divided by absolute T must equal the change in entropy for such a process.
We reasoned that the change in entropy for the vaporization of most molecules is about the same: 88 Joules per mol per K, Trouton's Rule.
We then discussed the importance of delta G STANDARD, emphasizing that delta G standard for a reaction MUST MAINTAIN concentrations of any aqueous reactant or product AT ONE MOLAR and any gaseous reactant or product AT ONE ATM pressure. Naturally, these conditions cannot be maintained as a reaction proceeds but delta G standard WILL tell us how a reaction will PROCEED (towards reactants or products) as a reaction proceeds towards the EQUILIBRIUM (NON-STANDARD) concentrations and partial pressures.
This is shown in the relation: delta G = delta G (standard) + RT lnQ
and, AT equilibrium, delta G = 0 = delta G (std) + RT ln K , which rearranges to delta G (std) = - RT lnK at equilibrium, of course. So, for a given reaction at a given temperature, since K is a CONSTANT, SO IS delta G standard !!!
Because we have no class this Friday, I will offer a "5 steps to a 5" review session on Thursday.

AP: Thus far, I am very impressed with the effort and quality on your Solubility Eq. exam, the hardest exam of the year. I know objectively that this was the hardest test, by far, this year yet you brought your A game and are doing very well.

Today, we talked more about entropy and we derived the second law of thermodynamics, one of the most important equations in life: dS (univ) = ds (sys) + dS (surr) > 0 for any spontaneous process. "You can't break even" i.e. any exothermic reaction that "happens" (spontaneously) will always lose/release some energy as dissipated heat that cannot be used for work. This "waste"-heat will cause a net increase in the entropy of the universe.

We then rearranged this equation into the Gibbs Free Energy equation. Noting that dS and dH are remarkably constant over large temperature ranges, dG can be determined over a range of temperatures by using dG = dH - TdS. This way, we can use the relatively constant values of dH and dS (so we can just use the standard temperature values of dH and dS), we can vary T and see at what temperature a reaction becomes SPONTANEOUS (i.e. no continuously applied BATTERY/energy source needed for the reaction to continue), which is when dG just becomes negative.

Honors: discussed potential energy/enthalpy diagrams and related them quantitatively to formation reactions and other chemical reactions or physical processes. We related the reactions in Tables G and I to the energy diagrams; we also discussed the meaning of "mole of reaction" and how to treat the energy term in an equation proportionally to the stoichiometry of the reaction.

Regents: we reviewed the factors that affect rates of chemical reactions; then we began to discuss exothermic and endothermic reactions as related to enthalpy diagrams.

Regents: we discussed the five factors that can influence the rate of a reaction (temp, concentration, pressure (for gases), surface area (for solids and liquids), and addition of a catalyst; we also explained the relationship between the nature of the reactants (covalent molecules vs. dissolved ions) and the rate of reaction.
Tomorrow is Day 1; we have a gas laws lab. Please bring in a 12-ounce aluminum can (preferably empty), tomorrow.
Thanks.

Honors: we showed how a balanced chemical equation can be used to determine the RELATIVE rates of disappearance of the reactants and the relative rates of appearance of the products.
We then discussed reaction mechanisms and then we went on to potential energy diagrams for exothermic and endothermic reactions, noting the important points: PE Reactants, Activation Energy, PE Products, delta H.

AP: we discussed entropy and predicted the change in entropy for a given reaction or process. We related the third law of thermo to the ABSOLUTE standard molar entropies of various substances, which we then qualitatively predicted. We then applied Hess's Law to calculate the CHANGE in entropy for a given reaction.

Regents: we applied the stoichiometry of a balanced chemical equation to see the relative rates of disappearance of reactants and formation of products.
We then began to discuss how factors can influence the rate of reaction by affecting the frequency of collisions per second and/or affecting the force/energy of collisions per second. We also discussed the requirements for an "effective" collision i.e. a collision that results in bond breakage/chemical reaction.
Here is a link to edline.com for our current list of labs:
https://www.edline.net/files/53caa75729ea3c083745a49013852ec4/2006-2007LabList.pdf

Honors: we completed a typical cooling curve and did the calculations for the energy lost as a gas is cooled, condensed to a liquid, the liquid is frozen, and the solid is further cooled.
We then just began a discussion of our new unit: Kinetics and Equilibrium.
Make sure that your labs are updated by Monday afternoon. That is your ticket to the bonus test.
Later today, I will post the list on our website. For now, here is a link to the file on edline.com:
https://www.edline.net/files/53caa75729ea3c083745a49013852ec4/2006-2007LabList.pdf

AP: we had the big kahuna today: the solubility equilibria exam. The questions were straightforward but you had to be more careful and do more manipulations than on any other test this year.
Now, we can master Thermo and Electrochem and sprint towards AP Test Day with an AP (part I or part II) exam per day! Good times.

Regents: we talked about rates of chemical reactions and how they are quantitatively measured. Tomorrow, we will get into the main part of the kinetics unit by explaining 5 factors that influence the rate of a chemical reaction.
Make sure that you do the text reading and questions regarding calorimetry/heating/cooling curves.

Honors: we did calculations of the various parts of the heating curve. We will continue with calorimetry and also do some cooling curve calculations, tomorrow.

AP: we finished the solubility equilibrium unit by doing some problems for reinforcement.
We then began our Thermodynamics unit by talking about the mathematical definition of entropy, "S".
Test tomorrow, good luck Varsity!
p.s. I uploaded, to edline.com, the SmartBoard notes/problems that we did at extra help today.
Here is the link: https://www.edline.net/pages/St_Anthonys_High_School/Classes/7095/Assignments/

Honors: we had our Math of Chem 3: Gas Laws exam. I will grade them over the next few days; so far, I glanced at two tests of students who come to extra help and they were both perfect except for one minor problem involving circular reasoning (NOTE: circular reasoning means trying to explain a statement by just restating the statement: "I always tell the truth BECAUSE I never lie" is an example of circular reasoning. Don't ever use that type of "reasoning". It is meaningless).
Hope to see more of those high scores.

Regents: we talked about specific heat capacity. Qualitatively, substances with high specific heats require a lot of energy to heat up and these substances have to lose a lot of energy to cool down. Water has a relatively high specific heat capacity.
We then did a calorimetry problem in which we determined the specific heat of an object. This was determined via calorimetry during which heat is exchanged between the hot object and the cooler water.
We then just started our new topic: Kinetics and Equilibrium.
MAKE SURE that your labs are all up to date by Monday.

AP: we further discussed salts that are more soluble in lower pH/ more acidic solutions. We then did a quantitative comparison of the solubility of magnesium hydroxide in water vs. in a relatively acidic buffer solution.
We then played "will a precipitate form?" and solved for the grams of precipitate and % precipitation. We will do another selective precipitation problem tomorrow and then we will begin one of the final topics: Thermodynamics i.e. dG = dH -TdS

AP: we did a "suppression of dissociation via common ion" problem complete with comparison of % dissociation with and without the common ion in solution. We then did a "competitive equilibrium" problem in which two or more cations are in solution, one of which is "selectively" precipitated by added just enough of a salt that has an anion that will more readily form a precipitate with one of the cations in solution. We then did the common follow-up question about the % of the mostly precipitated ion that is still in solution JUST WHEN the other cation is ABOUT to precipitate.
We then moved on to discuss/explain which salts can have their solubility influenced by the pH of the solution. ALL SALTS will become more soluble in acidic solution EXCEPT: ALL chlorides, bromide, iodides, nitrates, and perchlorates; END OF LIST! Notice the connection: these ions are all the conjugate "bases" of strong acids.
p.s. hydrogen sulfate salts can be made more soluble in BASIC solutions because the HSO4- will react with the excess OH-.

Honors: we finished general characteristics of solids, liquids, and gases; then we began our final math of chem subtopic: heating and cooling curves. More on that on Thursday. Tomorrow is the Math of Chem 3 exam which focuses on the behavior and laws of gases.
Follow the test-taking advice that was listed after the last test so that you do not make careless errors tomorrow. Make sure that EVERYTHING is explicitly labelled.

Regents: we had our Gas Laws exam today. I will return them by Thursday. That was probably the last test of the third quarter so you can calculate your third quarter average before the weekend.

Honors: we covered the time and rate versions of Graham's Law in all of their permutations. Then, we reviewed properties of gases, liquids, and solids.

Regents: we did a cooling curve heat loss calculation and then did a question set from Topic 4, which will be the focus of tomorrow's exam.

AP: we went from calculation of molar solubility of a sparingly soluble salt to the molar solubility of that salt in a solution with a common ion. This is an example of a Le Chatelier suppression of dissociation of the salt. Generally, in the ICE table calculation, you will ignore the dissociation of the common ion from the insoluble salt relative to the common ion's concentration from the common ion salt. We calculated the percent dissociation with and without the common ion present in solution.
We then went on to "will a precipitate form?" problems, which involves comparing Ksp vs Qsp.
Writing the dissolution equation in the correct order is crucial.
We finished with a lengthy, will a precip form into a "how much precip forms?" problem.

http://highered.mcgraw-hill.com/sites/0073656011/student_view0/chapter16/elearning_session.html

Here are a couple of links showing titration techniques and questions:
http://dvaction.northwestern.edu/mediaplayback.php?id=76#

http://www.uwplatt.edu/chemep/chem/chemscape/LABDOCS/catofp/measurea/concentr/titrate/titraon.htm

DIHYDROGEN MONOXIDE, OH MY!

AP: we looked at all permutations of sparingly soluble salts in equilibrium with a SATURATED solution of their respective ions. We showed that, given the Ksp of any of these salts, you can calculate (1) the molar solubility of the salt: "the number of moles of the salt that DISSOLVES per liter of solution FORMED" and (2) the MOLARITY of each of the ions in solution.
REMEMBER, though we use the same letter, s, the molar solubility of the salt does NOT mean the same thing as the MOLARITY of the dissolved ions. Of course, if you know the salt, you can get the molarity of the dissolved ions from the molar solubility of the salt simply by multiplying the molar solubility of the salt by the COEFFICIENT of the
dissolved ion in the balanced solution equilibrium equation.
We then went on to compare the solubilities of the SAME TYPES of salts and showed that you CANNOT readily/easily/by simple inspection of the Ksp's compare the solubilities of salts that have DIFFERENT empirical formula ratios.
We then briefly spoke about the heart of the unit, which involves Le Chatelier and the common ion effect. In most of these problems, we will do a TWO-STEP SOLUTION. We will do regular stoichiometry (COEFFICIENTS are KEY!) in a SRFC table; then, we will do an equilibrium calculation using the Ksp and an ICE table. This will seem long at first but these problems are shorter yet they require more thought than buffer problems. Check out the tutorials that are on our website.

In the "5 steps to a 5" book, we did the stoichiometry unit. Gauge your comfort level at approximating and NOT using a calculator on the timed part I questions. You must work accurately (first) and quickly (second) on the AP exam.

Honors: we finished Dalton's Law as applied to collecting a gas over water. When you see that situation, LOOK FOR the temperature and the Table of Vapor Pressure of Water values. Then ,apply Dalton's Law knowing that some of the total pressure is due to the pressure of the water vapor.
We then just began talking about Graham's Law as it relates to the kinetic energy, velocity, and rate of effusion of lighter vs. heavier molecules. Check out the formulas in the notes and tutorials and we will finish out the gas unit on Monday.

Regents: we explained and labelled the FIVE parts of a heating curve of a given substance showing the changes (or lack thereof) in kinetic and potential energy that occur for each part of the "curve".
We did quantitative energy calculations for each part. The parts that involve a change in temperature/average kinetic energy call for the formula "q = mcdT", which is heat added (in Joules) equals MC delta T ( that old skool rapper emcee Delta Tee!)
For the parts of the curve that have no temperature change due to the change in phase/potential energy only, we simply use q = mdH, which is heat added = mass times the heat of fusion (melting) or the heat of vaporization (boiling); all of the relevant values are in the Reference Table as are the formulas!
We will cool down with a cooling curve on Monday. There IS a test on Tuesday on the Gas Law unit as well as on the heating/cooling curves.
I will put up the text answers this weekend. STUDY STUDY STUDY. The end of the quarter is nigh.

Happy St. Patrick's Day!!!

Regents: we finished the gas law unit by doing a few problems (emphasizing that STP means 273 K and 1 atm - see Reference Tables) and then reviewing the kinetic-molecular theory of gases.
We then moved on to the next math of chem topic which related energy changes to physical changes/phase changes in matter. We started to draw out and explain a heating curve. We will do a cooling curve also, tomorrow.

Honors: Math of Chem 2 test today. If you did not do well, go back to your notes and learn the methods that are shown there.

AP: we covered the titration (and curve) of a strong acid by a strong base. We then did the titration curve of a polyprotic acid while emphasizing the dominant species at each significant part of the curve. We related pH to the multiple pKa's in the multiple buffer regions of the curve.
We then introduced the most challenging unit in the course: sparingly soluble salt equilibria. We need to get a big jump on that tomorrow so that you can make a dent in that unit over the weekend.

If you want to improve your test performance, here is what you can do:
Do the test problems EXACTLY as we do them in class, NOT the way your friend showed you, NOT the way your tutor showed you (some tutors are loaded with cheap tricks that only work on simple formulaic problems). I teach each problem type in the most efficient, logical, and fool-proof way BASED ON MY OWN STUDENTS' past experiences and past errors. After twelve years of teaching, tutoring, and seeing the same common errors occur again and again, I specifically show you how to avoid these errors BEFORE you make them on your test. I really marvel at the resistance (from some of you) to solving problems the way that you are presently taught. There are demonstrably better ways to solve some problems. I use these demonstrably better ways every time; furthermore, I can PROVE that the way that we solve problems in class leads to better accuracy, better speed, and better clarity.
As I have said before, you can think "outside the box" when/if you get to grad school. Before that, you need a solid base of knowledge. That does NOT mean that you can't question or challenge a particular method; it does mean that you need a rationale for your decisions.
Test taking tip #1 for math of chem problems (as always demonstrated in class):
1. carefully read the question and LABEL each quantity or substance given (e.g. initial volume, mass of solute...); 2.copy the data exactly, with units, to your test paper. 3. write the relevant general equation. 4. rearrange the equation, algebraically, so that the unknown variable is by itself on one side of the equation. 5. plug the data into the equation and solve (use parentheses in your calculator!) 6. cancel the units from numerator to denominator and make sure that the result matches the expected unit(s) from the question.

AP: we had one of the biggest tests of the year featuring a buffer and titration question, one of which is extremely likely to be your first part II question on this year's AP Chem exam.
The next two weeks of material is RELATIVELY difficult and will demand your time and priority, as you will see. When you understand that material, though, the rest of the course will be relatively EASY.

Regents: we finished the gas laws and looked at the ideal gas law, which is obeyed when gases behave "ideally". We discussed this gas behavior with respect to the tenets of kinetic-molecular theory, which is just a fancy name for talking about gases at the particle level.
We may be able to finish the gas law unit tomorrow so be prepared for a test on that unit early next week.

Honors: we did the Ideal Gas Law in its myriad forms. We discussed kinetic-molecular theory and related it to the conditions under which gases behave more ideally (high T and low P).
Tomorrow, we have our second math of chem exam. We have covered a lot of material for that test so make sure that you can do each problem type backwards and forwards. Do well!

AP: we did a full titration set of a weak base -strong acid titration. We analyzed the graph of the data from said titration.
We then discussed acid-base indicators and how to choose a proper indicator for a particular equivalence/end point pH level.

Regents: we reviewed Charles's and Gay-Lussac's Laws and then introduced Boyle's Law and Avogadro's Law for gases that behave ideally. It is important to understand the relationship among the variables of P,T,V, and moles (n) and how to explain that relationship in terms of kinetic energy, collision force, and collision frequency.
Worksheets and relevant hw are posted.

Honors: we explained from the particle level to the macroscopic level, Charles's Law, Boyle's Law, Gay-Lussac's Law and Avogadro's Law. Worksheets and relevant hw are posted. A set of objectives for Thursday's exam is also posted.

There is an error in the file posted on our website:

031307 AP AP Sample Titration Problem

I can't access the website right now so I put the corrected file on edline.com
Log onto edline and download the corrected file at this link:
AP Sample Titration Problem File

This site has good buffer and titration simulations/tutorials. Just scroll towards the bottom of the page. Also, this site has a virtual titration simulator; just follow steps 1 through 5, in order, and then do the calculation before you type in your answer to step 6: good for extra visual review.

Honors: we covered Boyle's and Charles's Law. We explained how and why each law results from the force and frequency of gas particle collisions. We looked at each law graphically. We will do the remaining separate gas laws tomorrow. Test on Thursday will cover stoichiometry, solution stoichiometry, measures of concentration (formulas must be memorized), solution dilution, colligative properties/calculations, solubility curves, soluble vs. insoluble salts (and hydroxide bases), all factors that affect net solubility and rates of dissolving.

Regents: we started the combined gas laws and explained two of the gas laws that are part of the combined gas law: Gay-Lussac's Law (constant V and moles of gas) and Charles's Law (net constant P and moles of gas). We drew the graphs that correspond to these laws, also. This unit is covered in Topic 7 in the orange review book and chapter 15 in the text.

AP: we went through a full titration of a weak acid by a strong hydroxide base and then of a weak base by a strong acid. We were most interested in the initial pH, the pH at halfway to the equivalence point (pH = pKa or, for a weak base titrated by a strong acid, pOH = pKb), the pH at the equivalence point, the pH just PAST the equivalence point, and, finally, the pH after much excess titrant has been added, i.e. the final (minimum or maximum, respectively) pH.
We looked at the titration curve that accompanies each of these titrations.
It is VERY important that you draw out, reason, and visualize what is occurring for each problem; students in the past confused different types of problems and did not write out the proper equation for what was occurring or they did not do the problem in a logical sequence, which led to incorrect reasoning.
Naturally, it takes a lot of practice and repetition to discern each type of question given that there are so many permutations of question types. I put up even more tutorials and solutions to assigned questions that should cover all of these permutations.
Wednesday's exam is one of the top three most important exams in the course, the exam after that is THE biggest and toughest exam in the course, and then, the electrochem exam will complete the trifecta of the most challenging tests that you will take this year.
Bring your "A" game to these tests!

AP: we learned four ways to make a buffer solution and then we quantitatively calculated how to make a buffer of a particular pH. You must choose a weak acid with a pKa that is close to the desired pH of the buffer solution.
We looked at the general form of three of the four types of titration curves and the telltale signs of each type of curve.
We then began our first six-part titration, which is just the regular calculation of the pH of, in this case, a weak acid. We will be doing titrations all Monday and Tuesday. Over the 3-day weekend, practice all covered material.

Honors: we covered the remaining permutations of solubility curve problems using various quantities of water. We discussed soluble vs. insoluble salts; the charge density of the ions of the salt determines the degree of solubility of a salt. We stated that insoluble salts form dilute saturated solutions and soluble salts form concentrated saturated solutions.
We began the next subtopic of the math of chem marathon: The Gas Laws. Preview all of the assigned gas unit material and do some of the problems; this section is relatively easy because the formulas are not complex and its just plug and chug.

Regents: we had our stoichiometry , solutions, and solubility curve exam today. People need to attend extra help to work on their test-taking skills. Careless errors were made due to a lack of writing out the provided equations and simply plugging in the values and units from the question.

Regents: TEST TOMORROW/THURSDAY, Day 3.
We covered each type of solubility curve problem with respect to saturated, unsaturated, and supersaturated solutions. Tomorrow's test will cover up to and including solubility curves.
Make sure that you are prepared for problems involving:
-balancing equations and the using that equation to determine relative moles of reactants and products
- mass to mole and mole to mass problems
-mole to mass, mole to volume of a gas at STP, mole to number of particles
-Molarity problems relating grams of solute, molar mass of solute, and volume of solution
- ppm, % by mass, and % by volume measures of concentration
- solution dilution problems
-colligative properties and the effect of salts vs. molecules on freezing pt. depression, boiling pt. elevation, and vapor pressure lowering.
- factors that affect the solubility of a given solute in a given solvent.
Good luck tomorrow. MAKE SURE that you come in prepared with your scientific calculator and several pens and pencils.

Honors: we discussed the factors that influence the degree of solubility of a given solute in a given solvent and also factors that influence the rate of dissolving. We then looked at solubility curves and did the various calculations involving the formation of saturated, unsaturated, and supersaturated solutions. We also calculated the extent of precipitation when a saturated solution is cooled.
Be careful about scaling up or down when you have a solution that does NOT contain 100. g of water. The way to avoid errors, in this case, is to draw out the solutions and label the relative amounts of solute in the saturated solutions containing 100.g of water and the other amount of water.
We will do some more of these problems and go onto our next topic: the gas laws, which you will complete over the 3-day weekend.

AP: we covered one of the types of buffers and showed how acidic buffer solutions can react with added strong acid or base to minimize change in pH. We then did a quantitative problem using the all-important SRFC table, which is like an ICE table but it accounts for the changing volume of the solution and it really shows you what happens to a limiting reactant reaction i.e. usually the added acid or base is limiting and completely reacted to form the products; this process alters the ratio of the acid to its conjugate base in the buffer solution, which will change the pH slightly. More examples and a chart of the FOUR ways to make a buffer solution, tomorrow.

AP: we began the ultra-important common ion effect/ buffer solution problems; we showed what occurs via Le Chatelier when a salt with a common ion is added to the weak acid in solution; the ionization of the weak acid is suppressed and equilibrium shifts towards the un-ionized acid.
We then derived the acidic and basic forms of the Henderson-Hasselbalch equation.
We will be learning about buffers and then 6-part titration problems in which buffer solutions necessarily form during the titration. Those problems will seem long at first but, with practice, will become quite mechanical.

Regents: we did the long haul and covered some ground today; we finished molality/colligative properties problems. You must know how to name any salt or molecule and know that molecules (except acids) do not dissociate upon dissolving; you must know the number of particles that a given formula unit of a salt dissociates into.
We learned factors that influence the solubility of a given solute in a given solvent; we also discussed factors that influence the rate of dissolving.
We went on to do solubility curves, which are found on Table G of your reference tables. We covered and applied the meaning of a saturated, unsaturated, and supersaturated solution. More practice with this tomorrow. You should finish the Orange Review Book Topic 7 questions before Thursday's test.

Honors: we finished some quantitative colligative properties problems and then went on to compare the relative freezing and boiling points of a group of various solutions.

Honors: today, we returned to the Math of Chem Unit. We covered solution dilution and concentrations of individual anions and cations before and after dilution. We moved on to percent by mass and percent by volume concentration calculations as well as parts per million concentration calculations. Then, we began colligative properties and molality. More problems involving them tomorrow. I am letting you know straight up that there are no tests this week but keep up with the homework and practice please.

Regents: we covered ppm, percent by mass, and percent by volume calculations. We then covered colligative properties as affected by concentrations of dissolved particles. We learned that ionic compounds, because they dissociate into more than one mole of particles per mole of compound, have a greater affect on freezing point depression and boiling point elevation than the same concentration of a covalent molecular compound (unless the molecule is an acid).
Make sure that you can do quickly and easily do the Orange Review Book Section 7 questions that we have covered, the homework, and the practice worksheets and tests by Thursday. If you can do so, you will ace the next test.

AP: we learned that high charge density metallic ions form acidic solutions by causing high O-H bond polarity among their H2O ligands, which causes and H+ to break off and form H3O+ in solution, thus increasing the acidity of the solution.
We then went on to discuss Lewis Acid-Base Theory and we applied it to several examples; we also did equation writing for metal oxides and nonmetal oxides in water and learned that these are Lewis acid base reactions.
We then did a salt pH problem. Tomorrow, we will begin the king of all topics in chemistry: buffer solutions.

AP: very long test today but it covered several important topics. As you can see though, if you know how to set up one equilibrium problem, you pretty much know how to solve most or all of them. The next test will have nonstop equilibrium problems so keep up the good work with those.

Honors/Regents:ice cream, blend-ins, and good times. Next week, we will discuss the "colligative properties" that were responsible for the quick-freezing of your liquid ice cream mixture today. I will assign some text reading and problems for this weekend.

AP: we did a few acid-strength explanation problems; then, we moved on to the prediction and explanation of the acidity or basicity of a given salt. We learned that certain ions hydroyze water and that other ions do not; water hydrolysis results in either an increase or a decrease in the pH of the solution. We did a couple of pH calculation of acidic and basic salts by using conjugate pKa and pKb values.

Honors: we did the aforementioned Nuclear test. good times. There will be some stoichiometry/solutions hw over the weekend.

Regents: we did some more ppm and molarity calculations; then, we learned two more measures of concentration: percent by mass and percent by volume.
More text hw regarding solutions this weekend. There will be a solutions and stoichiometry test next week.

Go Nukes! Excellent news for the Honors classes:
BOTH classes achieved a 96 average on today's test! Lots of hundreds and hot-97's. Maybe you found the test easy but there was a broad range of questions that required proper calculation and memorization; so,the test was not a giveaway. Thanks for putting in a solid effort over the long vacation. I noticed that the corrections that you handed in over the break looked very good, also. Keep up the good work!
Time to celebrate with some colligative properties tomorrow! Bring in some "blend-ins" and don't forget your winter gloves.
See you then.
Mr. Cicale