Week of Nov 26th.

Equilibrium unit outline!  (Objectives can be found here, under the Equilibrium tab)  Test is Thursday, Dec. 6!

On Monday, Nov 26th we reviewed a bit from the Reversible Reactions activity – including the definition of reversible reaction, dynamic equilibrium and examples that allow us to compare reactions that either “don’t happen”, “go to completion” or reach an equilibrium.   This led us to the idea that we need a way of measuring the extent to which a reaction occurs….the equilibrium constant.  The rest of the period you worked on ChemActivity 39.

Homework was to read as much of Ch. 14 as you had time to.  It is becoming increasingly clear to me that you guys need to read…it really helps and will help you meet your goal of doing well on the AP Exam and getting college credit.

On Tuesday, Nov 27th I handed test back and we spent the short class working on test corrections.  Too many mistakes were made on the kinetics test and it is important that you review this material since it is really a pretty important part of college chemistry (and the AP exam).   Plus, understanding how reactions occur is essential to ALOT of other fields related to chemistry – environmental and biochemistry, for example! Understanding biochemical pathways, enzyme action, etc. what happens to pollutants in the environment are all studied from a kinetic standpoint!

Homework: Finish test corrections

Instructions for test corrections

  1.  Find the correct answer and explain why it is correct (or at least why the choice you picked was not)
  2.  Make up a sample question that test the same concept and answer it.  This can be hard, but will make the biggest impact in helping you learn/remember the concepts!
  3.  Rewrite explanations completely and correctly.  You don’t need to make up new sample questions for this.

Wednesday, Nov 28: We started with Le Chatelier Exploration lab.  The purpose of this was for you to see what happens when you have a system at equilibrium and you cause changes to it.  It is hard, sometimes, to visualize what we are talking about when all we are dealing with is symbols and numbers…we followed that up with this animation.  You made predictions and then saw what happened to the color of the solution as concentration of a reactant or product was changed.

Next we did a little review of equilibrium constant which you can check out in this PDF.  It also has the homework assignment and answers to the first few pages of ChemActivity 40 on the reaction quotient (a quantitative way of measuring shifts from equilibrium).

Homework: Ch 14 (19,21,23,24,29, 37, 39, 41, 55, 57, 65)

Friday, November, 29th: Today we started with a warm-up doing some of  probllems listed in the homework below (#6,7, 61).  I lectured on Le Chatelier’s principle and we did some practice (le chatelier’s ship and this worksheet from Sandra Piepho). The rest of the block you worked on hoemowrk problems.

Homework: Ch. 14 (6, 7, 9, 10, 11, 12, 25, 26, 27, 61, 63, 69, 71, 73, 75, 77, 81, 93, 97)

Friday, November 30: Today we did a quick warmup which you can see on this PDF, just to review partial pressure.  Then I introduced the idea of Kp (very similar to Kc, but using Partial pressures instead of concentrations).  Here’s the notes (thanks to Mike Biggs for the powerpoint and the practice test, etc!).  The rest of the block you worked on practice problems and homework.  Here’s the calendar for this unit.  If you were absent, please come get a copy of the practice test – don’t want to post online.

Homework: problems Ch 14 (51, 53, 85, 99, 101, 105)

Up to Thanksgiving

On Friday Nov. 16th, I needed to head to the Dr. so you all hung out in Mark Dickson’s room and worked on your practice test.

Monday the 19th you took your test…ended up taking most if not all of the class. Ugh.

Tuesday was short, but we did this little lesson on reversible reactions using a phet simulation.  If you didn’t finish in class, you were to finish it over the break.

Calendar, etc. coming…

Nov 15: rate constant and nuclear reactions

Today we started with a warm-up problem from the 1994 exam…don’t have a digital copy, though. Key points were that you needed to be able to do stoichiometry to solve for concentration at a later time and you needed to know what to do when there was an intermediate in the rate determining step.  . I sort of glossed over exactly how to do this, but the idea is that you just substitute in one rate law for the intermediates concentration.

 

Anyway, next we took notes using these skeleton notes for activation energy.  Here are my answers and my notes for Nuclear reactions.  I don’t have digital copies for the nuclear reactions worksheets I handed out.

 

Ialso handed out a practice test which we will work on tomorrow in class.

Nov 13: Integrated Rate Laws

Today we did some review of integrated rate laws by doing problems 4-10 in ChemActivtity 58.  If you need help with this, check out the movies posted on the Unit 5 page of the blog.

Homework is to watch this video and do some textbook problems!! Also, remember to wear proper lab attire tomorrow!

Week of Nov 5

Advice of the week: Read the book!!

Monday I handed back the test and we talked about a couple of problems with the wording and a few places where lots of people made mistakes. Overall, the multiple choice sections were well done,though.  I also handed back the Boltzman distribution explanations.  Many of you needed improvements…talk about molecules, not just theories.  Cite the Boltzman distribution explicitly.

I did a short lecture on reaction mechanisms, just to introduce the concepts so that when you started your design lab, you’d have the necessary background for the iodine clock  reaction.   I did not go into how a reaction mechanism is determined since we have not yet covered rate laws, just gave a general idea and some vocabulary like elementary step and rate-determining step.

The rest of the block you spent working on the design lab “Factors that affect the rate of the iodine clock reaction.”  Lots of students had questions about the difference between the title and question in this lab since they are nearly the same. Hopefully, you noticed that the question also includes the reaction to be studied.  I think next year I will reword this to purpose and have you all provide a bit more context.  Balancing redox reactions continues to be a challenge and many groups were hung up on this part for 30 minutes or so.  Next year I will have that completed for homework.  Each group member takes a reaction….something like that.  In any case, we needed more time to plan because of it.

Tuesday was a professional day…

Wednesday we started with a lesson on rate laws.   I used my powerpoint notes and Chemactivity 57 and it went fairly quickly.  The rest of the class you finalized procedures for the iodine clock experiment.  I don’t think enough of you did the homework that was assigned, because Friday’s practice problem was challenging for many of you!

Thursday we spent the entire class working on the iodine clock lab.  Some surprising things…hotter temperatures make the mixture turn yellow, not blackish-purple.  I wonder if there was something wrong with that starch!   Also, low concentrations took a really long time and didn’t seem to turn very purple…a limit to what our eyes can detect?

Friday was a short class and I tried to do too much,  I think.  One practice problem on rate laws turned out to be a bit challenging and that really threw several students, but we made it through.  I made a video for this.   We did have a chance, finally, to talk about the units for k, though.   The lesson on integrated rate laws could have gone better, I didn’t know how to help you graph on your calculators so that took a long time, too.   We made it through a couple different practice problems, though, enough to allow you to do most, if not all, of the homework problems.

Here’s a lecture video introducing the integrated rate law. It shows how to use graphical analysis to determine the order and shows differences in half life for various orders.


Here’s a video of an integrated rate law problem.

My advice for the weekend is to finish you lab write-up (this includes rate calculations, a graph, an individual, thoughtful conclusion…use checklist and/or rubric), read and do your homework (textbook problems). The test is Friday, Nov. 16.  We only have a 4 day week this week, so it’ll be here in no time!

Hurricanes and Halloween

This week was crazy.  On Wed you took your gases test. Thursday we started the kinetics unit by starting with some demos and a simulations to learn collision theory.

On Friday we reviewed collision theory, talked about the Boltzmann Distribution, did the Boltzmann Rock Paper Scissors Demo, and you wrote explanations of catalyst and temperature effects on reaction rate. The rest of the block you spent calculating rate!

Homework was to finish rate calculation packet.

Nov 1: Kinetics

Today we started with a little discussion of lab report ethics since I’d been having to confront a couple of you about collaborating too much on your lab work.

Then while you waited for the simulation on the unit 5 page to load, I had you drawing bar graphs of the atoms with various speeds.  We talked a little about what that graph meant and then did the Boltzman bucks rock paper scissors game to illustrate how that happens.  We then completed the Boltzman worksheet.

Next I did some demos to show factors that affect reaciton rate: concentration (Mg and different concentrations of HCl), surface area (CaCO3 and HCl), and catalysts (MnO, NaI and H2O2).

The rest of class you learned collsion theory using the PhET simulation.

Homework was to read about catalysts: the article, the pages in the textbook, the video on unit 5 page, plus one problem from ch 5 (5.89, I think, check the calendar!)