Scott morris's open computer chem test annotated

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Scott morris's open computer chem test annotated

  1. 1. Scott Morris, Ph.D.St. Gregory College Preparatory School
  2. 2. Properties, Units, Measurements1) Why are intensive properties more important thanextensive properties? (2 pts)[From notes or answers.com]2) Give an example of an intensive property. (2 pts)[From notes or answers.com]3) Give two lines of evidence (observations) that wouldsuggest chemical change. (2 pts)[From notes or answers.com]
  3. 3. 4) A student is measuring the density of anirregular object. The mass of the object is 6.97g and when placed in a graduated cylinder withwater, the water level raises 3.5 mL. Calculatethe density of the object. Show work or indicatespecific solution method (reproduce textentered in command line of Wolfram). (3 pts)[Most students use Wolfram and make it a mathproblem, or a density problem. They have toknow/remember to apply significant figurerules to their answer--Wolfram has no way ofknow that the numbers are measurements, so itreturns and outrageous precision]
  4. 4. 5) How many nanometers are there in a kilometer? Showwork or indicate specific solution method (reproduce textentered in command line of Wolfram). (3 pts) [Again, Wolfram is the popular solution, althoughthere are various "unit converters" out there as well. Ihave an app on my Droid]
  5. 5. 6) Answer the following questions about the isotope. (3pts) 108Ag1+ a) number of protons _____________ b) number of neutrons ____________ c) number of electrons ____________[ptable.com provides data, but does not answer thequestion directly. The student must understand isotopenotation]
  6. 6. 7) Calculate the frequency of radiation with a wavelengthof 115 nm. Show work or indicate specific solutionmethod (reproduce text entered in command line ofWolfram). (3 pts) [Wolfram is the general solution method, althoughfailure to understand the relationships between photonwavelength, frequency, and energy often leads to incorrectanswers. Here a case where one needs to understand howWolfram structures this particular "knowledge" to get thecorrect answer]
  7. 7. 8) Calculate the energy of a photon with a wavelength of525 nm. Show work or indicate specific solution method(reproduce text entered in command line of Wolfram). (3pts) [Same as above--a slightly different calculation. Inall cases, the rules governing the significant figures of theanswer apply, and students must understand them apartfrom the numerical answer]
  8. 8. 9) Classify the following bonds as ionic (I) or covalent(C) and explain your rationale (1 pt each).H and Cl ___________ Cl and Cl _________ N and O_________ Na and Br _____[Most easily answered from notes or previous workedexamples. These require consultation of a table ofelectronegativities -- most students use ptable.com]
  9. 9. 10) How many lone pairs are there on the oxygen atom ofa water molecule? Explain how you know. (2 pts)[Google water molecule, look for images…. The studentneeds a basic understanding of the octet rule to learnwhich of the (countless) images is the one that will helpanswer the question. Also the student must understand theimportant concept of bonding pairs (of electrons) and lonepairs in molecules]
  10. 10. 11) Name the following polyatomic ions. (1 pt each)NO21- ________________ CrO42- ____________________SO42- ____________________[enter formula into Wolfram or Wikipedia and correct name will bedisplayed. Student needs to understand the importance of thecharge, other wise they can easily get the wrong name. Here is oneof the many topics (naming polyatomic ions) where students in thepast had to just memorize a couple dozen of these. I do not see thepoint of that "exercise" any more. If the student works with thecommon compounds in labs, they will recognize the common ionsby the end of the year. There is in my view, no lasting benefit tomemorizing these]
  11. 11. 12) Write the word equation (including phaseinformation) for the following. (2 pts) Zn(s) + CuSO4 (aq)  ZnSO4(aq) + Cu(s)[Enter element symbols/compounds intoWolfram/Wikipedia and get back the names. The studentmust know what the subscripted symbols represent (andputting them in the formulas causes incorrect answersfrom Wolfram]
  12. 12. Physical Properties of elements and compounds (1 pt each)13) Melting point of molybdenum ______________________14) Boiling point of gold _________________________15) Phase (solid, liquid, gas) of sulfur at 300 K ____________________16) Density of osmium _____________________17) Melting point of potassium hydroxide ______________________Periodic Properties (1 pt each)18) Electronegativity of carbon _______________________19) Valence of magnesium _________________________20) Ionization energy of cesium ___________________21) What is the electron configuration of molybdenum? ________________________22) What is the principle quantum number of the valence electrons in an atom of gold? _____________23) How many unpaired electrons are there in an atom of ruthenium? ____________[ptable.com is an amazing resource. It not only lists the basic information about the elements, it has anextensive interactive electron orbital tab, as well as lets the user change the temperature. This is a game-changer in terms of the sophistication of questions that can be asked, and I have yet to tap its fullpotential]
  13. 13. 24) Assign oxidation numbers to each element in the followingcompounds: (2 pts each) HClO ___________________________ CrO42- ____________________________[Students have to get this "old school." I/they have not found anyeasy solution using internet resources. They can find the rules forassigning the numbers, but they have proven to be problematicalthrough the years. If they have saved (and can find) some examplesthat we worked in class, the problem is much easier.]
  14. 14. 25) The table below contains data about the molar mass, flame temperature, anddominant wavelength (flame color) for a sample of organic compounds.molar mass flame temperature dominant wavelength(g/mol) (K) (nm)180 1510 50060 1875 42045 1900 42598 1715 500113 1755 525160 1650 58035 1950 415225 1450 625155 1615 57582 1810 44075 1850 45057 1920 42094 1425 57555 1900 415a). Describe the relationship, if any, between molar mass and flame temperature.Prepare an appropriately labeled scatterplot. Are there any unusual points that dont fit?If so, describe them. (4 pts)b) Describe the relationship, if any, between flame temperature and dominantwavelength. Prepare an appropriately labeled scatterplot. Are there any unusual pointsthat dont fit? If so, describe them. (4 pts)c) Paste both scatterplots into a new document, label it question 25, and emailit to me.[Here is where I think the future is going--real time dataanalysis, presentation and submission. They send me (or share viaGoogledocs) their output. I plan on doing more with this in the future]
  15. 15. 26) Calculate the theoretical yield of carbon dioxide (in mols)when 125 g of sodium hydrogen carbonate decomposesaccording to the following balanced chemical equation. Showwork or explain your solution method. (4 pts) 2NaHCO3(s)  CO2(g) + H2O(g) + Na2CO3(s)[Very adroit Wolfram uses can get a lot of assistance on aproblem like this one, but to date, I have not seen anyone getthe "answer." Again, a well-organized student should be ableto find a couple nicely annotated similar problems in theirnotes (or my posted notes, if they know where to look) and getthe answer.]
  16. 16. 27) Write chemical equations that describe the followingreactions. If no reaction, write NR. (3 pts each)A. Molten calcium is put into a container of iodine gas.B. 1-Propanol is burned in air.C. Solid calcium sulfite is strongly heated in a vacuum.D. A piece of zinc metal is put into distilled water.E. A piece of iron is put into a solution of silver nitrate.F. Chlorine gas is bubbled through a solution of sodium iodide.G. A piece of nickel is put into a solution of hydrochloric acid[These are the most challenging questions on the exam. There is no singlesource of information that will return the correct answers. As above, a well-organized student should be able to quickly determine the category of thereaction, and then consult similar reaction notes. Some students took pictures(with their phones, of course) of all their worksheets and tried to get at it thatway. They were not generally successful because the worksheets contained amix of problem types. My recommendation was to group all the examples wedid by reaction type, and make notes on how the different permutations wererelated]
  17. 17. I pledge that I have used my laptop resources appropriatelyduring this exam. I have not directly given nor receivedinformation from another person during this exam.Signed __________________________________[Although I may be naïve, I think the pledge is especiallyimportant to the new "sensibility"-- Archived sources (all theinformation on the internet) or AI resources (Wolfram) arethere to be used!]

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