Balancing Redox Reactions Quiz and Announcements

The quiz to completed for tomorrow, Tuesday, April 19th, 2011 is below. This is review from last fall and notes on how to balance a complex redox reaction were part of the notes package given out today in class. Please remember this week is another opportunity to take a practice AP Chemistry Exam. The test will be from 1999 and the opportunities to take it are Thursday night (4/21) from 7:00 pm to 9:00 pm OR Friday after school (4/22) from 2:30 pm to 4:30 pm OR Saturday morning (9:00 am to 11:00 am). Also, the solutions to the final two problems (1992 #3 and 2009 (B) #5) from the Chapter 19 work packet have been posted on the Events Calendar under today's date (Monday, April 18). I will be collecting the packet tomorrow to check for completion of work.

2004 (Form A and B) Free-Response Questions #2 and #7 Solutions

The solutions to the 2004 Free-Response Questions (#'s 2 and 7) from the Chapter 19 work packet are posted on the Events Calendar under the date Friday, April 15th, 2011. The homework for the weekend is 1992 Free-Response #3 and 2009 Free-Response Form B #5.

1999 Free-Response Question #6 Solution

Go to Events Calendar to view the PodCast for the solution to the 1999 Free-Response problem #6. It is posted under the date, Thursday, April 14th, 2011. Tomorrow morning (Friday, April 15th) at 6:30 a.m. is another review session for the AP Chemistry exam. Also, for homework tonight from the Chapter 19 work packet, complete problems 2004 Free-Response #2 and 2004 Free-Response (Form B) #7.

Solutions to WebAssign Problems and Some Reminders.

Remember, tomorrow your Chapter 17 Take-Home-Test is due. There is a reason that I showed you the presentation on Kidney Stones on Friday. That is to convey to you the idea that acids increase the solubility of non-soluble (or low Ksp) solids. Keep this in mind for a question on the exam. Also, the Chapter 17 WebAssign is due tomorrow. On the Events Calendar are two solutions to problems on WebAssign. One is for the pH determination during a strong acid / strong base titration. This is posted under the date, Saturday, April 10th and is for WebAssign #8. The second solution is for the pH at the equivalence point of a weak acid / strong base titration. This is for #10 on WebAssign. The Ksp for calcium hydroxide lab is also due tomorrow.

Completed Solution - #3 Ksp Packet

Below is the finished solution to #3 from the Ksp packet. We started #3 in class, but ran out of time. The "Q" was larger than the Ksp value given, so a precipitate will form when the two solutions are placed together. Because a precipitate will form, the B.C.E. table will be used. Notice in the B.C.E. table, the two to one ratio of fluoride ion to barium ion is taken into account by dividing the 1.100 moles of fluoride ion (the limiting reactant) by two. This is also repeated for the formation of the precipitate barium fluoride. When solving for "x" in the Ksp problem, adding "x" to the barium initial concentration was not taken into account because the disparity between the Ksp value and initial concentration of barium ion was large. The percentage between the two was 0.4%. Notice how a confirmation was done at the end of the problem to ensure that the problem was done correctly. A podcast was made showing the solution to #4 of the Ksp packet. The solution can be found on the Events Calendar of the class website under the date April 4th.. Please finish #5 for tomorrow.

Titration / pH Determination Problem Solution

In class on Friday, April 1st, a solution to WebAssign problem #9 was started. It is a difficult problem, so I made a Podcast showing a solution to the problem. The file can be found on the class Events Calendar under the date, Sunday, May 3rd. Also, #8 from WebAssign is similiar to to #9, but not as complicated. Number 8 only deals with a strong acid and a strong base in the titration. Number 9 deals with a weak base and strong acid in the titration. Therefore; #9 involves equilibrium and the Hendereson-Hasselbalch equation. Make sure to complete the quiz on the previous post for class on Monday, May 4th. Have a good weekend.

Buffer Quiz

Below is the quiz for making a buffer that needs to be completed for Monday, April 4th. Also, look back to the blog for information about a solution to WebAssign #9. It is a pretty difficult problem, so I am going to do a podcast on the best way to do the problem. Have a good weekend.