IB HL II Chemistry at GMHS

April 25: Water and soil

admin — Wed, 25 Apr 2012 16:25:45 +0000

Today we started with a little review of equilibrium and Le Chatelier’s principle using some worksheets from the Chem 1 textbook. Then we extended those concepts to talk about Ksp and the solubility of ionic compounds. (Next year, hope to include the barium chromate + acid demo to show how pH affects solubility – maybe will do this with soil concepts next class). Next we went into some water pollution topics using this powerpoint from last year. Water treatment review led to my demo using charcoal to remove color from the purple koolaid. On your copy I starred the slides that are most important for the IB exam. We talked a bit about soil and SOM using this ppt, but still need to get into CEC and salinization of soil.

Homework: Study for Mock Exam on Tuesday, May 1

April 23: Environmental Review/Study Guide

admin — Wed, 25 Apr 2012 16:22:10 +0000

Today I was absent. You worked on this review/ study guide all period.

April 19: Titrations!

admin — Thu, 19 Apr 2012 17:41:56 +0000

Today I lectured almost the whole class…ugh…but there were so many questions!! Anyway, we started with the neutralization page of the study guide I’d handed out awhile back (so many of you had lost it!). I changed a couple in the box part so that some of the salts produced would change the pH (titration would not result in solution with pH 7).

Next we did these notes: http://vimeo.com/40670564

Then these notes: http://vimeo.com/40670634

Then this worksheet. Some of you convinced me to let you play around with the indicators so before even completing the worksheet the class was putting drops of NaOH and HCl in microplates and adding various indicators to see the color changes.

Homework: Exam Review. Next class I will be out. You will have time to work on the environmental study guide and practice questions.

April 17: Buffers

admin — Tue, 17 Apr 2012 17:33:55 +0000

Today I handed out some review stuff for Environmental(study guide of air pollution + study guide for waste + practice q’s) so if you’d like to get working on that, please do! We’ll spend one class (next Mon. or Wed.) working on it.

The rest of class we spent working on buffers (notes and problems). I lectured and did the demo. You can see the demo here. The last 25 minutes of class or so you had time to work on webassign.

See google calendar for schedule. Mock Exam: April 27!!

April 11: More Salts…

admin — Wed, 11 Apr 2012 16:51:20 +0000

Today I thought we would start buffers, but after this clicker, it seemed as though we needed more practice with predicting pH of salts b/c it is essential that you understand what is happening with conjugate acids and bases so that you can understand why buffers form and how to make them. So after the clicker we did some practice and then did the problems below. No one was able to complete them so please have a look at them before we meet again on Tuesday (Friday I will be out and you’ll be working on a practice exam!).

Homework: Webassign and above practice problems.

April 9: More Salt Hydrolysis

admin — Mon, 09 Apr 2012 16:46:05 +0000

Today I handed out these notes and had you read them while I spent some time with the HL Bio 2 kids. Most of you seemed confused by them so I gave some notes explaining how to determine whether an ionic compound will change the pH or not. The steps for this are described on the last pages of ChemActivity 47. You all spent most of the rest of the class doing the last page of CA 47.

Homework: Webassign!

Mar 28: Salt Hydrolysis

admin — Mon, 09 Apr 2012 16:41:19 +0000

Started with warm-up asking to identify conjugate based and solve for Kb based on Ka and Kw. This led to discussion of salt hydrolysis. Did some pages (model 2) of CA 47 and then did the salt hydrolysis kit lab. It was a short wed. At the end of class I asked you to write equations for the reactions occurring in the lab, but no one had enuf time to do so. The plan was to start next class with this.

Mar 26: Test day

admin — Mon, 09 Apr 2012 16:34:54 +0000

Took all class to take organic reaction test (note to self: scheduled based on band trip and IB HL Bio)

Mar 22: Ka and Kb problems

admin — Thu, 22 Mar 2012 17:13:15 +0000

Today we did some lecture on Ka and Kb, how to interpret pKa and pKb from data book and some problems. Notes are in the video here. The answer to the last problem given in the video is given below (image), but the problem kinda doesn’t make sense…we also did some practice with this worksheet.

The rest of class we spent working on learning the relationship between strength of conjugate acids and their bases with a chemtivity packet.

Homework: study for test on organic reactions!

Mar 16: More O-chem + a little acid

admin — Fri, 16 Mar 2012 19:37:20 +0000

Today we worked on predicting reactions…took nearly the whole class! Some of you finished and worked on a practice IB question (I will hand out these to all of you on Tuesday). Together we went over the retrosynthetic analysis questions. Here’s the answer key for the packet.

During the last 20 minute of class we reviewed acids and bases. My assessment is that you have forgotten how to do calculations for pH for weak acids and you’ve forgotten some of the vocab (conjugate pair, for example). So we’ll start there next class.

Agenda for next time:

Strong vs. Weak Acids: the ones you have to memorize and the rest…
Definitions of acids (L, B-L, A) and other vocabulary
Ka to Kb to Kw and calculations of Ka and Kb for weak acids
Comparison of strength of acid and its conjugate