28 Questions for Final Exam - General Chemistry | CHM 1045, Exams of Chemistry

Download 28 Questions for Final Exam - General Chemistry | CHM 1045 and more Exams Chemistry in PDF only on Docsity! CHM 1045 Dr. Light December 12, 2001 FINAL EXAM Name __________________________ (please print) Lecture Section: 8 am 12:20 pm (circle correct one). Recitation Section ____ Meeting Time_______ This exam consists of seven pages. Make sure you have one of each. Print your name at the top of each page now. Pages 8 and 9 contain some thermochemical data, important constants, a table of electronegativities, and a periodic table. You may tear both off and use them for scratch paper. Show your work on calculations, including unit conversions, and give answers in the correct units and appropriate number of significant figures. In problems involving molecular and formula weights, you may use values rounded to the nearest 0.1 amu. The exam contains a total of 200 points. For the purpose of replacing a low test grade, divide the exam score by 2. If anything confuses you or is not clear, raise your hand and ask! Points (10) 1. How many L of a 0.12 M solution of Ba(OH)2 is required to neutralize 0.31 L of a solution of 0.47 M HCl? (Write the equation for the reaction, and show your work). (10) 2. A compound containing C, H, and Cl yields the following analysis: 10.0% Carbon, 0.84% Hydrogen, 89.1% Chlorine by mass. Determine the empirical formula. (Show your work). Page Points 1 ______ 2 ______ 3 ______ 4 ______ 5 ______ 6 ______ 7 ______ Total _______ For statistical purposes: (Question 27 + 28 _______ Questions 1-26_______) CHM 1045 – Fall 2001 FINAL EXAM Page 2 Name _________________________ (10) 3. Given the following balanced chemical equation: 2 Al(s) + 6 HCl(aq) -----> 2 AlCl3(aq) + 3 H2(g) 2.5 Moles of Al are added to a solution containing 9.5 moles of HCl. (a) Which reagent is limiting? (Show how you determine) (b) How many moles of the excess reagent will remain after the reaction? (c) How many moles of H2 will be produced in the reaction? (10) 4. Calculate the ÄH for the following reaction in two different ways, using the thermochemical data given at the end of the test: C2H2(g) + 2 H2(g) → C2H6(g) (a) Using heats of formation data. (b) Using bond energy data. CHM 1045 – Fall 2001 FINAL EXAM Page 5 Name _________________________ (10) 10. The National Ignition Facility at Lawrence Livermore National Laboratory has achieved scientific breakeven in laser fusion. The energy of 16 lasers is focused on the target, achieving PW (petawatt) power levels (1 petawatt = 1015 watts). How many photons of green light at 530 nm does it take to achieve 1 PW for 1 ns (equal to 1 MJ of energy).? For the following questions, put a check in the blank next to the best answer. Each question is worth five points. 11. What is the change in internal energy of a system that absorbs 635 J of heat and does 249 J of work? ____a) 635 J ____b) 884 J ____c) -635 J ____d) -386 J ____e) 386 J 12. Which set of elements is not in the correct order of increasing first ionization energy (lowest value first, etc)? ____a) Mg, Si, Cl ____b) Te, S, O ____c) Li, Na, K ____d) Al, B, C ____e) I, Br, Cl 13. Determine the number of unpaired electrons in the ground state atoms of P and Cl, respectively. ____a) 5, 3 ____b) 5, 1 ____c) 3, 1 ____d) 3, 2 ____e) 3, 5 14. What is the ground state electron configuration of Zn2+? ____a) [Ar]4s23d10 ____b) [Ar]4s23d8 ____c) [Ar]3s24d10 ____d) [Ar]3d10 ____e) [Ne]3s23d8 CHM 1045 – Fall 2001 FINAL EXAM Page 6 Name _________________________ 15. Which of the following molecules would be polar? ____a) SF4 ____b) CO2 ____c) BCl3 ____d) CCl4 ____e) PCl5 16. The density of gold is 19.3 g/cm3. A 3.4 mg piece of gold is hammered into a square that is 86 nm thick. What is the length of a side of the square? ____a) 0.020 cm ____b) 87 cm ____c) 4.5 cm ____d) 143 cm ____e) 14.3 cm 17. Consider four identical 1.0-L flasks containing the following gases each at 25o C and 1 atm pressure. For which gas do the molecules have the greatest average kinetic energy? ____a) H2 ____b) O2 ____c) NH3 ____d) SO2 ____e) same for all gases 18. What is the oxidation number of chlorine in HClO2? ____a) -1 ____b) +1 ____c) +3 ____d) +7 ____e) -3 19. In the compound, Na2HPO4, which element is present in the largest percent by mass? ____a) Na ____b) H ____c) P ____d) O ____e) not enough information given 20. Use the solubility rules to predict which of the following substances is insoluble in water. ____a) Cs2SO4 ____b) (NH4)2CO3 ____c) Pb(NO3)2 ____d) Hg2Cl2 ____e) LiBr 21. The specific heat of aluminum is 0.902 Jg-1oC-1 at 25o C. How much heat does it take to raise the temperature of a 12.0-g chunk of aluminum from 15.5o C to 35.5o C? ____a) 0.216 kJ ____b) 0.0108 kJ ____c) 0.0180 kJ ____d) 240 kJ ____e) 216 kJ 22. Which of the following sets is an acceptable set of quantum numbers? n l ml ms ____a) 1 1 0 -1/2 ____b) 2 0 0 1 ____c) 3 1 -1 -1/2 ____d) 0 0 0 +1/2 ____e) 2 1 2 -1/2 CHM 1045 – Fall 2001 FINAL EXAM Page 7 Name _________________________ 23. An atom containing 34 protons, 43 neutrons, and 34 electrons would have the symbol: ____a) 77Se ____b) 77Ir ____c) 77Tc ____d) 43Se ____e) 43Tc 24. Name the following hydrocarbons shown below in the order given: C4H10, C5H12, C2H4 ____a) propane, pentane, butane ____b) propane, hexane, ethene ____c) butane, pentane, propane ____d) propane, butane, ethane ____e) butane, pentane, ethene 25. Which is incorrectly named? ____a) BBr3 boron tribromide ____b) CO2 carbon dioxide ____c) Na2S disodium sulfide ____d) PCl5 phosphorus pentachloride ____e) KCl potassium chloride 26. A British thermal unit (Btu) is commonly used to measure the energy capacity of heating and air conditioning systems. A B.t.u is equal to 777.6 ft-lbs and a cal = 3.086 ft-lbs. What is a Btu in SI units of energy? ____a) 0.252 kcal ____b) 777.6 cal ____c) 4.184 cal ____d) 2.399 kJ ____e) 1.054 kJ 27. Which is incorrectly named? ____a) NaOH sodium hydroxide ____b) H2CO3 carbonic acid ____c) H2SO3 sulfurous acid ____d) H3PO4 phosphoric acid ____e) HIO hypoiodic acid 28. The formaldehyde molecule (CH2O) contains: ____a) 2 sigma and 1 pi bond ____b) 2 sigma and 2 pi bonds ____c) 3 sigma and 1 pi bond ____d) 3 pi and 1 sigma bond ____e) 2 pi and 1 sigma bond