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Chemistry 110, Fall 2003, Sections 1 and 2 Dr. Petr Vanýsek, Instructor The following is recommended study material for tests Test II, 13 or 14 October 2003 (24 problems posted 2 October 2003) It will cover chapters 5, 6, 7 and 8. Note that chapter 8 on Stoichiometry has lot of calculations in it. This lends itself to many multiple choice questions. Also, as previously, some of the assigned problems will be used in the test. The test has 50 questions, 2 points each. Allocated time: 1 hour 15 minutes. Note - only approved calculator, if any, can be used. 1. 10.0 g of sulfur and 10.0 g of zinc are allowed to react together. What is the limiting reagent, what is the product, how much of the product is made in the reaction and how much of the unreacted component is left? 2. A compound contains only carbon, oxygen and hydrogen. In combustion analysis of this compound, 0.0400 g of water and 0.220 g of carbon dioxide were produced. What is the formula of the compound? 3. What is the theoretical yield in grams of carbon dioxide, if 10.0 g of glucose is burned? 4. If 10.0 g of carbon dioxide was produced during burning of glucose, how many grams of glucose must have been burned? 6. Calculate the molecular mass of a given compound. 7. If 10 g of NaCl and 10 g of AgNO3 are separately dissolved and then solutions are mixed together, state what will be the precipitate and how much of it will be produced? 8. If solutions of lead acetate, sodium nitrate and ammonium sulfate are mixed together, predict what precipitate will form. 9. What is "mole", what is Avogadro's number, what is molecule? 10. Under what circumstances, if any, does it not take energy to break a chemical bond. 11. Balance a chemical equation for which the reactants and the products are given. 12. Identify a reactant, a product, a solvent and a solute. 13. Know (memorize) the table of solubilities from our text book (p. 253) and be prepared to use it to predict what will precipitate and what will stay dissolved. Write a net ionic equation for a precipitation for which the starting components are given. 14. Suppose you had oxalic acid, H2C2O4, and you wanted to make sodium oxalate, Na2C2O4. How might you do this? 15. Draw electron dot structures for molecules and predict from these structures the shapes of the molecules. 16. Ammonia has four pairs of electrons around the central nitrogen atom, and yet, we do not call it a tetrahedral molecule. Why not? What is the shape of this molecule? 17. When is a molecule considered to be polar? 18. How is it possible to estimate whether a molecule is polar? 19. What does electronegativity have to do with a bond dipole moment? 20. Distinguish between ionic bonding, covalent bond and polar covalent bond. 21. Know the names/formulas/charges of the following polyatomic ions: ammonium, acetate, nitrite, nitrate, carbonate, sulfate, phosphate. 22. Know the naming scheme of the old form and the systematic methods for binary compounds listed in table 5-3. 23. Draw electron dot diagrams for ions. 24. Distinguish between ionic and molecular compounds. How does this affect naming of the compounds? Know how to name compounds. 24 general areas posted 2 October 2003. More added 8 October 2003: 25. If the percent yield is 75%, how much more of starting material is needed, compared to a 100% yield. Try it. Common mistake is to assume that 25 percent more is needed. 26. Distinguish between the mole and a molecule. How many atoms are in one mole, how many are in one molecule... 27. Solve the test sequentially. Some problems rely on the result from previous question. If you miss the first part, you will miss the next. This is equivalent to a convoluted problem with many points assigned to it. One such problem is the whole sequence of combustion analysis calculation. Another is a stoichiometric calculation involving a limiting reagent 28. Balancing chemical equations. This is tricky to test on multiple choice problem. If equation Fe + H2SO4 --> Fe2(SO4)3 + H2 is given, the balanced form would look like this: 2 Fe + 3 H2SO4 --> Fe2(SO4)3 + 3 H2 The coefficients in front of the individual reactants are products are, in the sequence: 2, 3, 1, 3. Note that no coefficient means one. Thus, in the answer section you would be looking for answer x) 2, 3, 1, 3.
--- Last entry 8 October 2003 at 13:55. Quiz II, October 27 and 28, 2003. The emphasis will be on math, in particular, the algebra of proportions. 1. If it takes $142 to purchase 108 pieces of craft jewelry, how much will it cost to purchase thousand pieces of jewelry? 2. How many grams of silver chloride does it take to make thousand grams of silver metal? 3. How do the calculations in problem 1 differ from problem2? 4. Percentage problem: You are in the
business of delivering dry ice. The dry ice evaporates during transport. Assume that 20%
will evaporate prior to delivery. If you have to deliver exactly 100 pounds of dry ice,
how much do you need to load to make up for the loss due to evaporation? Test III, October 10 and 11, 2003 (Posted 3 November 2003, 21:54) NOTE: Section 2 has a new seating chart It will cover chapters 9, 10, 12, 13 and 14. I will put more emphasis on the material that I have covered myself and little emphasis on the material covered by the substitute teacher. As before, the emphasis will be on examples that I did in the class and on some of the assigned problems. The test has 50 questions, 2 points each. Allocated time - 1 hour 15 minutes. Please, know your seat number, bring the approved calculator and turn of your cellphones and other commucation devices. Note on the sample problems: They are rephrased questions from the test, made
more generic than the actual questions. Part of your learning experience, if you want to
use this guide, is to figure out the clues. Example: The
guide question: More guide questions: Given a formula, calculate molecular mass of a compound. Dilution question: You have a 5 mol/l solution, need to prepare certain volume of 2 molar solution. How many moles of sodium hydroxide are in 200 ml of 0.5 mol/l solution of sodium hydroxide? How many milliliters of 0.50 mol/l solution of AgNO3 need to be used to completely react with 100.0 ml of 0.25 mol/l solution of NaCl? For a particular reaction the reactants are at 10 kJ, the products are at 50 kJ and the transition state is at 100 kJ. What is the delta E reaction? What is a catalyst, what is its purpose, what are its properties? What is the reaction rate, how is it expressed, what are its units? What is chemical equilibrium, what leads to it, how is it described? What is exothermic and endothermic process, know examples, know how to distinguish the two. Concentration calculations: What is the molarity of 350 ml of a solution that contains 5.32 g of NaCl? What is a saline solution? What is solubility, how is it related to temperature? What is solubility product? How many moles of water are in 1 g of water? How
many molecules are in one gram of water? How
many grams of water are in one milliliter of water. What
is the relationship in reaction energy and activation energy between forward and reverse
reactions? Know
the relationship between order of reaction and concentration. What happens to the rate if
the concentration doubles? What
is the Le Chatelier’s principle? What
is a Chateaubriand?
What
are the units of energy, reaction rate, temperature, heat. Know
how to express chemical equilibrium and how to calculate it from given concentrations. What
are the properties of the chemical reactions at equilibrium. Know
what addition or removal of products will do to the chemical equilibrium. How will
pressure influence chemical equilibrium. How will added heat influence the equilibrium? If you know the
solubility product, calculate the solubility. If you know the
solubility, calculate the solubility product. What
is the equilibrium constant? What is the equilibrium constant of the reverse reaction? Quiz III November 24 and 25, 2003 (guide started 11 November 2003) 15 questions, 45 points total (i.e., 5 bonus points) All the material will be from Chapter 15. I will mention all the probed issues in the class. The material may or may not be found in the book. What is monoprotic, diprotic, triprotic acid? Know
examples.
The Final (guide started 5 November 2003) Section 1 (12:30 class) - Tuesday, December 9, 12:00-13:50 The final will have 68 questions, 3 points each, i. e. 204 points total. The 4 points are obviously additional credit. Not much, but it can help. The test will consists of 17 questions based on test I, 17 on test II, 17 on test III and 17 questions on material from chapters 14, 15 and 16. The questions based on previous tests may be the same questions as in the tests; however, chances are they will be modified. Practicing on your previous tests is definitely a good idea; memorizing the tests probably not. Test results: There will be no opportunity for you to pick up the result slips for the final. However, you can easily learn your score if you keep a copy of your test with marked answers and view the key for the test. The key will be posted here at this link after everybody took the test, Tuesday evening: http://www.chembio.niu.edu/electrochem/results_of_the_final_fall_2003.htm For the first three quarters of the final you have sample questions in your previous tests.
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