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UT CH 302 - Lecture notes
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CH302 Random Musings, April 13, 20041. The average for the second exam was about a 70, which is what I expected given the increased number ofquestions. The distribution is found below.James and Anna's Grade Distribution Plot01020304050607080020406080100120140160180I gave everyone credit for the quadratic problem before the exam and after the exam gave everyone credit forthe question in which you solve for Keq of NH3 equilibria because the problem was coded incorrectly. Therewere a few other problems that were answered at only around 25% that I would usually toss out but theyseemed to me to be quite fair. One was the question about the Ka of a weak acid at 1M with pH 4. Everyonejumped at saying the answer was 1 x 10-4 but if you think about it, the correct answer is 1 x 10-8 as you can findby just putting the numbers into the weak acid calculation. The other most-often-missed question was similar indesign and answered incorrectly for similar reasoning. The question was about the least soluble ion determinedfrom a Ksp and everyone jumped at the smallest Ksp value without thinking about whether you need to take thesquare, cube or fourth root. The correct answer was the square root value for CdS.2. There is one other problem I am thinking of tossing because of ambiguity but I will have to look at it a bitmore. Let me know if you have any other questions about the fairness of problems and I will consider them.3. I know that some of you who studied hard were disappointed with your grade. I of course would like to haveseen a higher average, but that is how it goes. For those of you who feel that you work and work and nothingseems to improve all I can say is, never give up. There is still time and I am more than willing to help you. Asalways, contact me to make an appointment and we will see what can be done. Remember, all you need to do isshow improvement on the final and that is the grade you will receive.4. I like to see grades for a course work out to an average of 2.7 or 2.8 (the CNS average), maybe higher if Ihave a good class (which this is.) For this reason I give out bonus point opportunities as needed to compensatefor the challenge of the exams. This semester I will give 30 bonus points that you can freely add to yourcumulative score in whatever way helps your grade.Thus, based upon the quiz and exam averages to date, the number of exempted students would be about 40 or50 without the bonus points. With the bonus points that number rises to about 120 to 140 students beingexempt, which is quite high for CH302 class (but again, you are a good class so I expect it.) The issue for me isthat some of you have not turned in your bonus points. When you think that these points are the equivalent of ahalf letter grade (for example turning an 86% into an A for the course), I am amazed that I didn’t get near 100%response. As it is, I have about 75% response to date for the two bonus questions. I am willing to let you turnin your bonus points late so you can get this boost, so e-mail them now following directions I have given.Believe me, very few of the 25% of you who have not done so are in a position not to take advantage of thisextra credit opportunity. I will have the third extra credit for you next week.5. As always, if you have grading issues, print out and turn in a change of grade request to James or Annaduring class and we will fix whatever ails you.6. We begin two final chapters for the course, Kinetics in Chapter 16 and Electrochemistry in Chapter 21. Iknow you will tire of hearing this, but these two chapters are rather challenging. The kinetics chapters is themost challenging mathematically and the electrochemistry is quite challenging conceptually, so try to stay ontop of the material as the lectures are given.7. As you can tell, I am holding my daughter in my arms. This is because 30 minutes ago she threw up and so Ihad to pick her up from child care. The good news is that I have kind of a free day the Tuesday the last week ofclass for review and evaluations, so I am going to shorten today’s lecture and use that day to catch up if I needit.8. Poetry Corner. I usually give this poem out during Chapter 20, but I forgot. Rules for Solubility, by way of Cornell UniversityPotassium, sodium, and ammonium saltsWhatever they may beCan always be depended onFor solubility.When asked about the nitrates,The answer’s always clear,They each and all are soluble,Is all we want to hear.And (slightly) chloride of leadMost every chloride’s solubleAt least we’ve already read,Save silver, mercurous mercuryEvery single sulfateIs soluble, Tis said,Cept barium and strontiumAnd calcium and lead.Hydroxides of metals won’t dissolve,That is, all but three,Potassium, sodium and ammonium,Dissolves quite readily.And then you must remember That youMust not “forget”Calcium, barium, and strontiumDissolve a little bit.The carbonates, insoluble,It’s lucky that it’s so,Or else, our marble buildingsWould melt away like snow.(Repeat, with feeling)Potassium, sodium and ammonium saltsWhatever they may beCan always be depended onFor solubility.And now some more serious stuff:One from Frost about why you should get off the beaten path and be your own person:The Road Not TakenTwo roads diverged in a yellow wood,And sorry I could not travel bothAnd be one traveler, long I stoodAnd looked down one as far as I couldTo where it bent in the undergrowth;Then took the other, as just as fair,And having perhaps the better claim,Because it was grassy and wanted wear;Though as for that the passing thereHad worn them really about the same,And both that morning equally layIn leaves no step had trodden black.Oh, I kept the first for another day!Yet knowing how way leads on to way,I doubted if I should ever come back.I shall be telling this with a sighSomewhere ages and ages hence:Two roads diverged in a wood, and I--I took the one less traveled by,And that has made all the difference.Robert Frost (1874 - 1963)A couch potatoes view of the road not take, by Edna St. Vincent Millay:The UnexplorerThere was a road ran past our houseToo lovely to explore.I asked my mother once -- she saidThat if you followed where it ledIt brought you to the milk-man's door.(That's why I have not traveled more.)Finally, a limerick (and a clean one at that) about studying for exams:Tenure DeniedA professor who flunked his whole classWas arrested for having the brass,In this modern


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UT CH 302 - Lecture notes

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