S14-Exam-1A-answers - Hunter College of the City University of New York Department of Chemistry and Biochemistry CHEM 102 General Chemistry I Spring

S14-Exam-1A-answers - Hunter College of the City University...

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Unformatted text preview: Hunter College of the City University of New York Department of Chemistry and Biochemistry CHEM 102: General Chemistry I Spring 2014 Exam 1 Version A Instructions: 1. Do NOT open this exam until you are told to do so. Opening the exam before the start of the exam is considered an act of Academic Dishonesty. 2. All answers must be bubbled into the scantron answer sheet. 3. No credit will be given for answers written on this exam. 4. You must use a #2 pencil to bubble in the answers on your scantron. 5. This is a multiple choice exam consisting of 26 questions (8 pages). There is no partial credit on this exam. 6. Attached to the back of this exam you will find 3 blank pages and a periodic table. You may remove these from the exam at your convenience. 7. On the FRONT of your scantron. • Write your last name, followed by your first name. • Write your exam version (A or B) 8. On the BACK of your scantron: • Write and bubble in BOTH your last and first name. Make sure to bubble in your names as follows: Last Name (leave a space) First Name NOTE: You must Bubble in the space on your scantron! Hunter College Academic Dishonesty Statement Hunter College regards acts of academic dishonesty (e.g., plagiarism, cheating on examinations, obtaining unfair advantage, and falsification of records and official documents) as serious offenses against the values of intellectual honesty. The college is committed to enforcing the CUNY Policy on Academic Integrity and will pursue cases of academic dishonesty according to the Hunter College Academic Integrity Procedures. Any suspected cases of academic dishonesty will be reported without exception. 1 Hunter College of the City University of New York Department of Chemistry and Biochemistry Questions 1-­‐ 5 refer to the table below. Fill in the table below and then select the correct answers to the questions below. Atomic Atomic Atomic #Protons #Electrons #Neutrons Charge Symbol Number Mass Number Ar 18 40 18 18 22 0 Ag 47 108 47 46 61 +1 1. The Atomic Number corresponding to the symbol Ar is A. 18 B. 40 C. 17 D. 20 E. 36 2. The Atomic Mass Number corresponding to the symbol Ar is A. 18 B. 40 C. 17 D. 20 E. 36 3. The number of protons corresponding to an atomic number of 47 is A. 47 B. 108 C. 61 D. 63 E. 107 4. The number of electrons corresponding to atomic number 47 and charge +1 is A. 108 B. 109 C. 107 D. 48 E. 46 5. The number of neutrons corresponding to atomic number 47 and atomic mass number 108 is A. 47 B. 108 C. 61 D. 63 E. 107 6. Phosphorous-­‐32 is an isotope of phosphorous that is routinely used in medical and biochemical studies. The isotope notation for phosphorous-­‐32 is which of the following: 31 32 33 31 32 A. 15 B. 16 C. 15 D. 16 E. 15 P P P 2 P P Hunter College of the City University of New York Department of Chemistry and Biochemistry 7-­‐9. The next three questions ask about the element calcium. 7. The calcium valence electrons are in the A. s block B. p block C. d block D. f block 8. The electron configuration of the Ca atom is A. [Ar]3s2 B. [Ar] 4s2 C. [Kr] 3s2 D. [Kr] 4s2 9. The electron configuration of the Ca2+ ion is A. [Ar] B. [Ne] C. [Ar] 4s24p2 10. The name for Na3PO4 is A. trisodium phosphate B. sodium (III) phosphate C. trisodium phosphide D. sodium phosphate E. trisodium monophosphorous tetroxide 11. The formula for vanadium (IV) nitride is A. V4N B. V3(NO3)4 C. V3N4 D. V4N3 E. Va3N4 12. The name for CO32— is A. carbon (III) oxide B. carbon trioxide C. carbonate ion D. monocarbon trioxide ion E. carbon trioxide ion 3 D. [Kr] 4s24p2 Hunter College of the City University of New York Department of Chemistry and Biochemistry 13-­‐14 Aluminum sulfate is made according to the balanced chemical equation: 2 AlO(OH) + 3 H2SO4 → Al2 (SO4) 3 + 4 H2O 13. How many dozen aluminum sulfate formula units are produced if 4.5 dozen H2SO4 molecules are consumed? A. 1.5 dozen B. 4.5 dozen C. 1 dozen D. 2.25 dozen E. 9 dozen 14. How many dozen of the AlO(OH) formula units are needed to produce 6 dozen molecules of H2O? A. B. C. D. E. 12 dozen 3 dozen 1.5 dozen 2 dozen 0.67 dozen 15. To the right are pictures of s, p, d, and f orbitals. Which statement below is incorrect: A. There are 3 p orbitals and each orbital has two lobes. B. There are 7 f orbitals and they have more lobes than the d orbitals C. There are no d orbitals in the n=2 energy level D. The maximum number of electrons that can go in a single d orbital is 10. E. The s, p, d, and f orbitals all have the nucleus at the center of the coordinate axis. 4 Hunter College of the City University of New York Department of Chemistry and Biochemistry 16. Complete the balancing of the following equation. Note that in the balanced equation, the coefficent in front of the HNO3 is 6. ____ Al2O3 + 6 HNO3 ___2___ Al + ___6___ NO3 + __3___ H2O Report answer in aluminum oxide : aluminum : NO3 : H2O A. 1:2:6:2 B. 1:2:6:3 C. 2:4:6:3 D. 1:2:6:1 17. Which statement is true about the reaction: Br2 (g) 2 Br(g) A. For every molecule of bromine reacted, 2 bromine atoms are produced, energy is released, and the container gets hotter B. For every molecule of bromine reacted, 2 bromine atoms are produced, energy is released, and the container gets colder C. For every 2molecules of bromine reacted, 1 bromine atom is produced, energy is released, and the container gets hotter D. For every molecule of bromine reacted, 2 bromine atoms are produced, energy is absorbed, and the container gets hotter E. For every molecule of bromine reacted, 2 bromine atoms are produced, energy is absorbed, and the container gets colder 18. Which statement is true about the reaction: 3O O3 A. This is an endothermic reaction because bonds are broken B. This is an exothermic reaction because bonds are broken C. This is an exothermic reaction because bonds are formed D. This is an endothermic reaction because bonds are formed E. One cannot tell if this is exothermic or endothermic because bonds are both broken and formed. 5 Hunter College of the City University of New York Department of Chemistry and Biochemistry 19-­‐20. Answer these questions about this Lewis structure for ozone (O3) proposed by a student in General Chemistry: 19. Which of the following statements is correct A. This is a valid Lewis structure because the octet rule is satisfied on all oxygen atoms. B. This is not a valid Lewis structure because the oxygen in the middle shares only 6 electrons. C. This is not a valid Lewis structure because the bonds are symmetric. D. This is not a valid Lewis structure because there are too many total valence electrons. 20. For the Lewis structure drawn, which statement is not accurate: A. There are a total of 6 lone pairs in the Lewis structure shown. B. The central oxygen atom has 2 lone pairs of electrons. C. There is one single bond and one double bond in ozone. D. This Lewis structure would predict that ozone has two different bond lengths. E. The double bond in ozone would be harder to break than the single bond. 21. Consider the balanced chemical reaction below that occurs in the atmosphere: 3NO(g) N2 O(g) + NO2 (g) Which statement below is an accurate use of nomenclature to read this equation A. 3 molecules of nitrogen oxide react to form 1 molecule of nitrogen dioxide and 1 molecule of nitrogen trioxide. B. 3 molecules of nitrogen monoxide react to form 1 molecule of dinitrogen monoxide and 1 molecule of nitrogen dioxide. C. 3 molecules of nitrogen (II) oxide react to form 1 molecule of nitrogen (I) oxide and 1 molecule of nitrogen (IV) oxide D. 3 molecules of nitrogen monoxide react to form 1 molecule of dinitrogen oxide and 1 molecule of nitrogen dioxide 6 Hunter College of the City University of New York Department of Chemistry and Biochemistry 22-­‐23. Consider another atmospheric reaction: CO + O CO2. Bond Energy Bond (kJ/mol) The valid Lewis structure for carbon monoxide has one carbon-­‐oxygen triple bond. A valid Lewis structure for carbon dioxide has two 347 C – O carbon-­‐oxygen double bonds. Draw the carbon monoxide and carbon dioxide 614 C = O Lewis structures that correspond to the description above and use the table of bond energies to answer the next two questions. C = O 839 22. The ΔH for the reaction is A. Exothermic and equal to 389 kJ/mol B. Endothermic and equal to 389 kJ/mol C. Exothermic and equal to -­‐389 kJ/mol D. Endothermic and equal to -­‐389 kJ/mol E. Can’t tell from the information given 23. Which of the following statements is not correct. A. The reactants and products are the system B. The initial energy of the system is the energy of the reactants C. The final energy of the system corresponds to the energy of the products D. On an energy diagram the energy of the products is above the energy of the reactants. E. On an energy diagram the energy of the reactants is above the energy of the products. 7 Hunter College of the City University of New York Department of Chemistry and Biochemistry 24. We can use the particle diagrams to the right to represent water in the different phases of matter. Which statement below is not an accurate statement about the particle diagrams for the water phases. A B C A. The water molecule H2O is being represented as a black dot. B. Box B represents water as a liquid. C. Box A shows that solids have their own shape D. Box C shows that gases fill the container E. Box B shows that solids have some disorder 25. Models can be oversimplifications as well as sometimes just wrong in what they show. Which statement below is a reasonable critique of these particle diagrams. A. Water has the chemical formula H2O and therefore it is never appropriate A B C to model it as a black dot. B. Solid water (ice) actually floats on top of liquid water and so the particles in B, which represents liquid water, should be more tightly packed (more dense) than the particles in A, which represents ice. C. The molecules in the gas phase are always in motion and so static models like C, which represent gas molecules, make it seem like gas particles can stop moving. D. Water molecules take up 3 dimensions in space so it isn’t appropriate to use 2 dimensional diagrams. 26. Look at the periodic table given and pick the statement below that is the least accurate at the table. A. Most elements on the periodic table are solids at room temperature. B. Most elements on the periodic table are metals. C. Most elements on the periodic table have filled octets. D. The inert gases are Group 18. E. Elements in Groups 1 and 2 are in the s block. 8 Hunter College of the City University of New York Department of Chemistry and Biochemistry This page is intentionally left blank 9 ...
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