Final Exam of 1st Semester

Thursday, December 15th, 2011 is your last exam of the 1st semester. It will cover all of chapter 11 and part of chapter 13. The test will be both multiple-choice and written (free-response) consisting of questions from old AP Chemistry exams. You were given a review packet in class of old AP Chemistry exam questions. I have supplied a pdf. file of the solutions to the review packet on the AP Chemistry calendar under the date, Tuesday, December 13th, 2011. The packet is meant to give you feedback for the correct answer, but also be used as a teaching tool to give you fairly a deep understanding of the concept. If you have any questions, come and see me before Thursday.

Bonding Strength Quiz

Answer the three questions of the quiz below. The answer from which types of bonding comes from previous lectures but also from today's lecture.

Thermodynamics Question

Below are the three questions that you need to answer for tomorrow, Thursday, December 1st, 2011. This will be graded at the beginning of class on the due date.

Organic Chemistry Independent Study

As I have promised, you will be given the opportunity to complete an independent unit of study over the Thankgiving holiday break. This unit of study is completely voluntary, but it is something that will help you on the AP exam next may. I have mapped out below where all of the resources can be found can be found and what the procedure will be for finishing the material.

The independent study will cover Organic Chemistry, which is Chapter 25 in your book. This will be a short, but complete unit on the chemistry of carbon. AP Chemistry is a course designed to be equivalent to an upper level college freshman chemistry course. Therefore, after the successful completion of freshman chemistry, a chemistry, biology, pre-med, or chemical engineering major would move on to a year long course in organic chemistry. The branch of organic chemistry in the chemistry tree is the largest. It is the chemistry that is the back-bone of the pharmaceutical industry, petroleum industry, and almost everything you buy without a prescription at the corner drugstore. Thousands of new chemicals are discovered every year and the vast majority of them are organic compounds. It is incredibly important, so a very minor amount of information known about it will be a benefit to you. This would help as you possibly move on to AP Biology, or get a 4 or 5 on the AP Chemistry exam and possibly move right into organic chemistry in your first year of college, or most important for right now, see a couple of questions pertaining to organic chemistry on the AP Chemistry exam. I do not cover this material in class because it historically is a very minor part of the exam and there just is not enough time to cover everything during the course, but also enough of the exam that it could be the difference for some to passing the exam or moving to the 4 and 5 region of the exam.

THIS INDEPENDENT STUDY UNIT IS OPTIONAL AND NOT REQUIRED FOR THE COURSE. IT IS DESIGNED TO BE AN ENRICHMENT TO THE COURSE AND A MINOR PORTION OF THE AP CHEMISTRY EXAM.

The unit will consist of you reading the chapter and studying the Chapter 25 Power Point that is available on the class Events Calendar, completing a practice test, and then finally completing a written take home quiz that will turned into me at the beginning of class Monday, November 27th, 2011. This take home quiz will be 20 questions. This is an opportunity for you to add a really good score to your assessment grade. It will be open book, open note, open internet, and open study buddy if you choose. I would suggest that everyone who wants to improve his or her grade take this opportunity and also those that are really serious about scoring well on the AP Chemistry test. The test is the only part of this independent unit of study that will be graded.

• The Chapter 25 Power Point can be found on the Events Calendar of my AP Chemistry web-page under the date of Fiday, November 18th, 2011. I have eliminated about 1/3 of the chapter from the Power Point. The independent study will focus on the classifying and naming of organic compounds and certain functional groups. Also, molecular geometry, bond angles, and hybridization that was learned in the previous unit will be applied to organic molecules.




• The Chapter 25 practice exam will be a .pdf file found on the Events Calendar under the date Friday, November 18th, 2011. The practice test consists of 32 questions. For each question, page numbers in the book have been given to guide you to the area in the book that you will need to read and study to answer the question.




• A VODCast of all of the solutions to the practice test will be posted to the Events Calendar under the date of Saturday, November 19th, 2011. It will be more than just answers. I will use the practice test as an opportunity to teach a deeper understanding of the concepts associated with each question.




• On Sunday, November 20th, 2011, the actual take home quiz will be posted on the Events Calendar as a .pdf file. You will need to print the quiz and complete it and be ready to turn in at the beginning of class, Monday, November 27th, 2011.

Below are links to four video resources that I found on the web that could be of use to you as you complete this independent unit of study.

• A VODCast/Power Point from Professor Chuck Wight of The University of Utah. This was designed for a first year chemistry course (like AP Chemistry) at UU, so it fits our needs quite well. Please keep in mind that the take home quiz will focus on material covered in the practice test, so some of what is presented you will not be held accountable for. Prof. Wight covers many functional groups that I will not be focussing on. The functional groups that I will hold you accountable for are alcohols, amines, halogens, and carboxylic acids. These four and all of the other functional groups can be found on page 1071 of your book. This YouTube video has a running time of almost eight minutes.
  



• The second VODCast that you can watch covers specifically how to name organic compounds. The naming system is governed by an international organization called IUPAC. You may see this acronym as you read the chapter or look on the internet. The acronym stands for International Union of Pure and Applied Chemistry. This YouTube video has a running time of just over nine minutes.
  



• The third internet resource that you can watch is a fairly humorous and catchy tune about naming organic compounds. There is a video accompanying the song. It is a good source to really condense many of the naming concepts for organic compounds. This YouTube video has a running time of two minutes and forty seconds.
  



• The fourth internet resource that I have to offer is a very short video that shows the resonance structure creation of an organic compound benzene. It does a very good job of illustrating the overlap of un-hybridized "p" orbitals to form the "pi" portion of a double covalent bond. You will read quite a bit about benzene and the delocalized bonds within the molecule. This video, I hope, gives you a better understanding of that concept.




• The fifth internet resource is a silly little video and song about benzene. Watch and get a little in-depth information about a very common substance found in industry.

If you would like to look at a cool software, you may want to download a molecular modeling software called Jmol. Use the link for the download. It is free-ware that works surprisingly well. On the Events Calendar under the date Monday, November 21st, I have a VODCast showing how to use the software. If you download the software and use it to make a molecule, print a picture of the molecule, and correctly name the molecule, I will award you 10 points extra-credit towards your homework grade. The molecule must contain atleast four carbon atoms, atleast one double bond (or triple bond) and one functional group or halogen atom. If you have a hard time loading the software to your computer, just by-pass the software and draw me a picture of a molecule on paper, but it must be colored. A hand drawn picture will be worth 5 points extra credit.

I will be checking my school email periodically over the break, so email me if you have any questions. Also, you do have my cell phone number, so please feel free to call or text me if you need any assistance.

Take Home Quiz and WebAssign

Below is the take home quiz that you were promised for the weekend. Please complete the problem and have it ready to turn in on Monday, November 14th, 2011. I have also placed a WebAssign assignment for Chapter 10 that will be due next Friday, November 18th, 2011. Please remember to keep watching all of the review videos from the class calendar.

Chapters 8, 9, and 24 Exam Review

Below this written is a key for all of the questions /problems presented in the review for the Chapters 8, 9, and 24 test. All of the concepts on the test are not covered by the review packet. I will list the topics not covered in the review packet so you can look at other materials from the unit of study. The test will consist of 35 multiple choice questions and 5 short answer questions. You will be supplied a periodic table (the one given for the AP Chemistry exam) and I will give you a electronegativity table, though one would not be supplied on the AP Chemistry exam. You will also be able to use a calculator. The multiple choice test will be given on Wednesday, November 9th, 2011 and the short answer will be given on Thursday, November 10th, 2011.

I have supplied more information than what is needed in the answers to the key below. I was more in-depth than what would be needed on the exam because I wanted to use the study guide and key as one last teaching tool. When answering an AP Chemistry free response question: (1) Do exactly what is asked to do. (Draw a Lewis structure, etc.) (2) Make sure to compare and contrast if asked to do so. (3) Any term used in the answer should be defined.

WHAT TO STUDY

1. Know how to define (non-polar) covalent, polar covalent, and ionic bonds and understand the mechanisms of how each is made.
   


2. You need to know from memory all parent geometries, molecular geometries, and bond angles. Know the criteria for each.
   


3. Know the concept of lattice energy and that the magnitude of lattice energy is dependent upon the magnitudes of the ion charges and the distance between the nucleus of both ions in the bond. For a large lattice energy, large charge magnitudes and small ion distances are needed. For a smaller lattice energy, small charge magnitudes and large ion distances are needed. L.E.=k(Q1Q2)/d.
   


4. Know all criteria for hybridized orbitals. On a previous blog post, all of the criteria and applications were written out.
   


5. Know how to determine the enthalpy (heat) of a reaction from the energy inputs (i.e. heat of sublimation, bond energy, ionization energy, etc.) and energy outputs (electron affinity, lattice energy). If energy inputs exceed energy outputs, a endothermic reaction will occur. If energy outputs exceed energy inputs, a exothermic reaction will occur.
   


6. Know how to choose the most plausible Lewis structure based upon formal charge. Zeros are preferred and the more electronegative element should be a negative number is not zero. Also, all formal charges must add up to the total charge of the molecule.
   


7. Know the basic concept of isomers. This is covered in its most basic form on page 1026 of your book at the very beginning of section 24.4. This concept is covered in the review from the year 1994, question #43. An isomer is a molecular formula that can have more than one Lewis structure that works for the number of atoms in the molecule. This is not to be confused with resonance structure, which is just the moving of a double or triple bond. This is completely different positions of atoms within the molecule with different types of bonds to achieve the different atom positions. I have given an explanation on the review.
   


8. Know how to define and recognize a Lewis acid and a Lewis base.
   


9. Know the rule to determine the coordination number of a Lewis acid is to double the oxidation (charge) number. The coordination number will be the number of ligands (Lewis bases) that will surround the Lewis acid (metal ion) in the middle of the complex ion.
   


10. Know the types of hybridization for a metal that are needed for different coordination numbers.
    


11. Know the basic naming system of complex ions.
    


12. Be able to write a net ionic reaction for the formation of a complex ion.
    
    

Hybridization Recap

I would like to go through a quick recap of hybridization for bonding.

• A single bond always involves only a sigma bond. A sigma bond is between two hybridized orbitals or a hybridized orbital with a non-hybridized 1s orbital of a hydrogen atom.



• A double bond always involves a sigma bond and pi bond. The pi bond originates from two non-hybridized p orbitals overlapping.



• A triple bond always involves a sigma bond and two pi bonds.



• Ligands are either covalent bonds or non-bonding electron pairs. A single covalent bond, double covalent bond, or triple covalent bond are all considered one ligand.



• sp^3 hybridization is required when four ligands surround an atom. The hybridized orbitals can be used for sigma bonds or to hold non-bonding electron pairs. Associated with the tetrahedral parent geometry.



• sp^2 hybridization is required when three ligands surround an atom. The hybridized orbitals can be used for sigma bonds or to hold non-bonding electron pairs. Associated with the trigonal planar parent geometry.



• sp hybridization is required when two ligands surround an atom. The hybridized orbitals can be used for sigma bonds or to hold non-bonding electron pairs. Associated with the linear parent geometry.

VSEPR Lab

You were given the VSEPR lab yesterday in class. The lab will be due next Friday, November 11th, 2011. The lab that you need to access is posted on the Events Calendar on the AP Chemistry web-site. VSEPR is an acronym for Valence Shell Electron Pair Repulsion. It is the repulsion of the electrons that create the geometric angles between the bonding and non-bonding ligands. Remember, non-bonding ligands repel more than bonding ligands. That is why the bond angles decrease as bonding ligands become non-bonding ligands within a particular type of parent geometry. Remember on the parent geometry trigonal bypyramidal, the equatorial bonding ligands transform to non-bonding ligands first because of the greater bond angles (120^o vs 90^0) allows for more space between the non-bonding ligands. (Non-bonding ligands repel more than bonding ligands.)

Molecular polarity - is a molecule symmetrical (same charge distribution all around the molecule) or asymmetrical (charge distribution is unequal around the molecule)? Symmetrical is a non-polar molecule and asymmetrical is polar. When you build your molecules, any difference in color for pipe cleaners used will cause the molecule to be asymmetrical, thus polar.

Please see me if you have any questions concerning the lab or concepts needed for the lab.

Halloween Take-Home-Quiz

Please complete the two questions shown below that deal with the Blowing-Up-Pumpkins demo done in class. Use your hand-out or book for the heats of formation and use this link for a table of bond energies.

Take-Home-Quiz

Below are the two images for the take home quiz that needs to be completed before class on Thursday, October 27th, 2011.

Take-Home-Quiz and Remedial Session Reminder

If you would like to earn back half of your points on the Chapter 5 Quiz, attend a remedial session from 6:30 a.m. to 7:15 a.m. tomorrow morning (Friday, October 7th,2011).

Below is the take home quiz that needs to be completed for tomorrow (Friday, October 7th, 2011). You have three choices as to what scenario could break the bond in question. The question does ask if more than one of the scenarios could break the bond, so all scenarios must be analyzed or you could miss out on receiving full credit. We will grade the quiz tomorrow in class. Have a good night.

Chapter 5 Quiz

Tomorrow is a quiz over Chapter 5, Thermochemistry. If you experienced success with the WebAssign set and you understood the pre-lab exercise for the Hess's Law lab , you should be fine with the material on the quiz. Below is a solution to the problem that I had for #8 on WebAssign. I was given three reactions to add together to get a target reaction. I did not use the third equation because two of the substances, water and hydrogen sulfate, are not part of the target equation and could not be factored out. The second equation is reversed and multiplied by two to achieve the correct factoring out. Remember, if a reaction is reversed, the enthalpy sign must be changed. Also, if a reaction is multiplied by some variable, the enthalpy must also be multiplied by that variable. Come and see me tomorrow if you have any questions.

Hess's Law Lab

Below are some of high points that I want to discuss about the Hess's Law lab.

• The water of the solutions is what captured the heat of the reaction. This remained constant at 100.0 mL (50.0 mL of one solution added to 50.0 mL of the other solution) for each trial of the lab. For calculation #1 of the analysis, mass is needed for q = s x m x delta T. Since the solutions are not pure water, the mass is determined by multiplying the total volume of solutions (after adding them together) with the density of the combined mixture. Since the mixture was mostly water, we did use the specific heat of water.


• The intent of the lab was not to prove the conservation of energy. There was a systematic error of heat being lost to the surroundings. This was true for all trials, so this factors itself out for the purpose of the lab. The only intent of the lab is to prove that achieving a heat of a reaction can be achieved through one step or multiple steps, given that the net of the multi-step approach is the same as the direct approach in terms of the same reactants and products.


• As indicated by the pre-lab, hypothetically, the sum of the heats of reaction for reactions #2 and #3 are supposed to equal the heat of reaction for reaction #1. Systematically across the board, this did not turn out to be true. The reaction #3 (hydrogen ions with ammonia) went way off the chart. I have a theory as to why. The ammonia solution used to make the 2.0 M solution for the lab was very old. Because water has evaporated from the solution over time, traces of some precipitate can be seen floating in the solution. It is my theory that as the reaction occured, the precipitate from the ammonia solution dissolved. As you will find out later this semester, some processes of dissolving are quite exothermic. This is my proposition for the undesirable results.


• I will be performing the experiment myself with new solutions. I will be giving you a write-up to place with this lab in your portfolio describing the inadequacies of the lab. This way, any criticism of your results can be placed upon the situation, not your abilities.


• IT IS NOT YOUR RIGHT TO FUDGE THE RESULTS TO MAKE IT FIT THE THEORY. IT IS YOUR RESPONSIBILITY TO PRESENT THE RESULTS "AS IS" AND EXPLAIN ANY DISCREPENCIES IN HOW THE THEORY AND DATA DO NOT COINCIDE. THE RESULTS ARE WHAT THEY ARE. SCIENCE HAS NEVER PROGRESSED BY MANIPULATING RESULTS TO GET THE DESIRED AFFECT. YOU WILL GET PAID MONEY IN THE FUTURE TO FIGURE OUT THE PROBLEM AND FIX IT, SO GET USED TO IT!! And now Mr. Brueckner is stepping off his soap box. :)

Key for Mole Ratio Lab Practice Quiz

Go to the AP Chemistry Calendar page and under today's date is a pdf file of the key for the mole ratio lab practice quiz. Remember, tomorrow you will be taking a quiz for real.

Chapter 4 Test Review

Below are images of a solutions guide to the optional practice exam. Remember, the pdf file for the Chapter 4 test review can be found on the AP Chemistry calendar. I changed the review since I made the key, so problem #15 is different. The bottom image is the solution to number 15.
You will be given all equations needed for the test. You will be able to use your periodic table. You will not be supplied with the solubility rules. If you remember the basic solubility rules, an assumption can be made that anything that does not fit a basic solubility rule is not soluble, thus a solid. The test is 20 multiple choice questions. Do not think that you do not have to do the work to solve a problem. Just looking at the answers will not suffice.

Chapter 4 Practice Exam

I have posted a practice exam for the chapter 4 test. The file for the test is on the AP Chemistry calendar under the date, Monday, September 12th, 2011. The test will be this Thursday, September 15th, 2011. The answers are on the very last page of the practice test.

Hydrogen Peroxide Titration Pre-Lab Questions

I have placed a Podcast on the AP Chemistry calendar under the date Friday, September 9th, 2011. The Podcast gives another example on how to balance a complex redox reaction in a basic solution. Feel free to view it as you complete the problems from WebAssign.

Below are the slides from the Power Point presentation of the pre-lab questions the the Analysis / Titration of Hydrogen Peroxide. On Monday, September 12th, you will be completing the lab. To complete the analysis, you will need to complete calculations like those shown below. Below this blog entry is the question that is to be completed for Tuesday, September 13th, 2011.

Take Home Quiz - Empirical and Molecular Formulas

Please answer all parts of the question below. Have the solutions to the problem ready for class on Tuesday, September13th, 2011. This type of question is a true AP Chemistry test question. What makes it so is that there are multiple parts of the test that require very different skills. Good luck.

Take Home Quiz

Below is the problem that needs to be solved for Thursday, September 8th, 2011.

Ecological / Responsible Chemistry with Dr. John Warner

For a chance to earn 10 points extra credit in your homework category, I would like to you watch two short videos and answer five questions. The two videos are from a talk given by an organic / industrial chemist by the name of Dr. John Warner. I had the pleasure of seeing Dr. Warner give his presentation in person at the American Chemistry Society conference in Denver last Sunday. He is the founder of a company that emphasizes creating chemicals that are chemically benign, which means they are ecologically neutral to the environment. Yet, the chemicals still do what they are designed for just as effectively as hazardous chemicals. He has a great message on how chemists / society can tackle the problem of environmentally aggresive chemicals by eliminating the toxicity in the design phase of a chemical. Dr. Warner and colleagues have come up with 12 principles of what makes chemistry "green". Those principles are in the images shown above.

Dr. Warner's talk is in two parts: Video 1 and Video 2

After you watch the videos, I would like you to answer the questions below and e-mail me the answers at cbrueckner@lps.k12.co.us .

1. What was Dr. Warner's orginal major as an undergraduate student at the University of Massachusetts in Boston?



2. Dr. Warner's picture appeared on the cover of a local Boston magazine with what other celebrity?



3. What event in Dr. Warner's life made him think about the possible toxicity of the chemicals that he had designed?



4. In Dr. Warner's opinion, what is a missing component of chemistry training programs (Master's and PhD)?



5. When is the best time to address the toxicity of a chemical?
   
   

Last but not least, below is the solution to problem #8 from the worksheet on solubility and ion concentration that was worked on in class on Friday. On Tuesday, September 6th, 2011, you must have the worksheet completed and the Ion Lab analysis completed. Of course, you can always work on WebAssign also.

Flipped Classroom

You are part of an experiment today. We are going to try a new, budding trend that I have learned of in science education known as the "Flipped Classroom". Instead of you coming into class on Friday, September 2nd and listening to me yap about some problem and showing you how to do said problem, you are going to learn how to do this type of problem online via a short instructional movie. The problem is the image below this text. Please read the problem and if you have any inclination on how to solve the problem, try it. If you have no idea, that is fine. Whether you try the problem or not, you then need to view the instructional video. The Quicktime Movie file can be found on the AP Chemistry calendar (<-- LINK) under the date Thursday, September 1st, 2011. There is no audio for the movie, but every step of the process is mapped out for you. Make corrections to your original attempt of the problem or write down the solution and take notes on the problem, just like you would do if I was lecturing to you in class. I will be checking for proof of viewing the movie (any means of recording the work that you have done) during class the next day. If you show up to class without doing any preparation work for class the next day, you will be sent down to the library to view the movie. This has consequences because you will not be allotted time to complete the homework associated with the material in class. If I may phrase it in another way, you will create more homework for yourself and not have the luxury of working with your peers (or me for that matter). I WILL NOT CONSIDER YOU HAVING THE VIDEO DOWNLOADED TO YOUR I-PHONE (or like device) AS SUFFICIENT PROOF OF PREPARING FOR CLASS. PENCIL OR PEN MUST GO TO PAPER. After doing this, you have completed what you are responsible for outside of class.

On Friday, September 2nd, 2011, you will do your homework on this material in class. I will be placing you in groups of four (the groups will be my choosing, thank you) and you will complete the homework assignment for this topic. The members of the group will help one another complete the homework. I will be walking around the room to help you, but to also ask questions to determine you level of comprehension, both as a group and as individuals. You must finish the assignment in class to receive full credit. If you do not complete the assignment because your are not prepared, that is nobody's fault but your own.

The write up for the Ions / Precipitate lab can also be completed after you finish your work presented in the movie. If you are efficient and thorough in your work, you will have no homework for AP Chemistry over the three day weekend. Please email me if you have any questions. I will respond if they are not sent too late.

Chapter 3 Test Tomorrow - Friday, August 25th, 2011

Below are all of the solutions for the review packet given for the Chapter 3 test. I forgot to give you back your solutions for the combustion analysis / empirical formula quiz that you completed earlier this week. An image of the quiz is given again below and the solution. Please use it as a study tool. Tomorrow's exam will consist of two old AP Chemistry exam questions. Each question will have multiple parts. The point value will be 23 points, which compared to the other exams that you will be taking, is a lower point value. You will be well prepared if you understand the review problems and you complete the Chapter 3 WebAssign. Come and see me tomorrow morning if you have any questions. I will be to school by 6:30 a.m.

Copper Iodide Lab

The copper iodide lab is due tomorrow, Wednesday, August 23rd, 2011. Make sure for the write-up to follow the format perscribed in the Formal Lab Report handout. Below are the solutions to the pre-lab incase you need a reminder on how to perform the calculations for the lab.
Please show the calculations for all trials, even if they contradict the perscribed formulas of CuI or CuI2. In your SEE statement, express possible a explaination(s) why those trials are not satisfactory. In the conclusion statement, detail if your results allow you to draw a definitive conclusion on what the empirical formula is, or do your results make the empirical formula determination inconclusive.