102-Exam-1A-F13 - Hunter College of the City University of New York Department of Chemistry Biochemistry CHEM 102 General Chemistry I Fall 2013 Exam 1

102-Exam-1A-F13 - Hunter College of the City University of...

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Unformatted text preview: Hunter College of the City University of New York Department of Chemistry & Biochemistry CHEM 102: General Chemistry I Fall 2013 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 21 questions (5 pages). Each question is worth 4.762 points. There is no partial credit on this exam. 6. There is one extra credit question on this exam (page 6). The extra credit question is worth an additional 5 points. 7. 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. 8. On the FRONT of your scantron. • Write your last name, followed by your first name. • Write your exam version (A or B) 9. 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. CHEM 102 Fall 2013 Exam 1A 1 Hunter College of the City University of New York Department of Chemistry & Biochemistry Multiple Choice Questions: (5 pts each) 1) Carbon dioxide (CO2) is a gaseous molecule that is used to produce carbonated beverages and soda water. Under the right conditions however, carbon dioxide can also exist as a liquid and even as a solid (this is what you know as “dry ice”). The diagrams below illustrate some or all of the phases of carbon dioxide microscopically. How many of the following statements about these diagrams are incorrect? A B C • Each black circle in this model represents one carbon dioxide molecule. • Diagram A represents solid carbon dioxide because the molecules are tightly packed and are arranged in a fixed position. • Diagram B represents solid carbon dioxide because even though the particles are not arranged in a regular pattern they are tightly packed and do not fill the container. • Diagram B represents liquid carbon dioxide because the particles are less tightly packed and will eventually fill the entire container. • Diagram C represents liquid carbon dioxide because the particles have a lot of space between them and have spread out to fill the entire container. a. 1 b. 2 c. 3 d. 4 2) Choose the pair of names and formulas that do not match: a. Sulfur hexachloride: SCl6 b. Magnesium perchlorate: Mg(ClO4)2 c. Copper (II) oxide: Cu2O d. Ammonium carbonate: (NH4)2CO3 3) Naturally occurring chlorine (Cl) consists of 2 isotopes, 35Cl and 37Cl. Based on the atomic mass for Cl that is given on the periodic table, which of the following provide a reasonable estimate for the relative percentages of each Cl isotope? a. 75% 35Cl and 25% 37Cl b. 50% 35Cl and 50% 37Cl c. 40% 35Cl and 60% 37Cl d. 25% 35Cl and 75% 37Cl CHEM 102 Fall 2013 Exam 1A 2 Hunter College of the City University of New York Department of Chemistry & Biochemistry 4) Which of the following is the correct molecular formula for the product that forms when calcium combines with arsenic? a. Ca3As2 b. Ca2As3 c. Ca2As d. CaAs2 5) Tripropyleneglycolmethylether, also know as TPM, is an organic compound used in the production of polyester plastics. TPM has the formula CH3O(CH2CHCH3O)3H. One molecule of TPM contains: a. 4 C atoms, 10 H atoms and 4 O atoms b. 10 C atoms, 10 H atoms and 4 O atoms c. 10 C atoms, 22 H atoms and 4 O atoms d. 16 total atoms 6) Which of the following formulas does not represent a binary molecular compound? a. CO b. NO c. KBr d. N2O4 7) What is the symbol for the ion that contains 46 protons, 45 electrons and 60 neutrons? a. 106Pd1-­‐ b. 106Pd1+ c. 105Pd1-­‐ d. 60Pd1+ 8) What is the sum of the total number of protons, neutrons, and electrons in the anion 51V+2? a. 70 b. 72 c. 74 d. 76 9) Which of the following diagrams illustrates a dz2 atomic orbital? A B C D a. A b. B c. C d. D z z x y CHEM 102 Fall 2013 Exam 1A x z z y x y x y 3 Hunter College of the City University of New York Department of Chemistry & Biochemistry 10)Which of the following statements is incorrect? a. 60Zn contains the same number of protons as it does neutrons b. 50Mn contains the same number of electrons as it does neutrons c. 41K contains the same number of protons as it does electrons d. 18O contains the same number of protons as it does neutrons 11)How many electrons are there in the 3d orbital of chromium when it is in its ground state? a. 3 b. 4 c. 5 d. 6 12)Which of the following atoms is paramagnetic? a. Be b. Ar c. P d. Zn 13)Which of the following diagrams accurately depicts the electron configuration of an atom that contains 6 electrons in the ground state? 1s 2s 2p a. b. c. d. [ ↑ ↓ ] [ ↑ ↓ ] [ ↑ ][ ↑ ][ ] [ ↑ ↓ ] [ ↑ ↑ ] [ ↑ ↓ ][ ][ ] [ ↑ ↓ ] [ ↑ ] [ ↑ ↓ ][ ↑ ][ ] [ ↑ ↓ ] [ ↑ ↓ ] [ ↑ ↑ ][ ][ ] 14)Which of the following ions has a noble gas electron configuration? a. Cr3+ b. Fe3+ c. Cu2+ d. Se2-­‐ 15)Rank the elements C, O, Na & Si in order of decreasing electronegativity value (largest number to smallest number). a. Na > Si > C > O b. O > C > Si > Na c. O > Na > Si > C d. C > O > Si > Na 16)Consider what happens when carbon and oxygen combine to form carbon monoxide. Which of the following statements about this process is correct? a. The carbon and oxygen atoms share 1 pair of electrons to form a covalent bond b. The carbon and oxygen atoms share 2 pairs of electrons to form a covalent bond c. The carbon and oxygen atoms share 3 pairs of electrons to form a covalent bond d. The carbon atom transfers its electrons to the oxygen atom to form a covalent bond CHEM 102 4 Fall 2013 Exam 1A Hunter College of the City University of New York Department of Chemistry & Biochemistry 17)Consider the following 4 molecules and arrange them from least polar to most polar: C-‐F a. b. c. d. C-­‐C C-­‐Cl C-­‐I A B C D B < D < C < A A < B < C < D B < A < C < D A < C < D < B For each of the following molecules, draw a valid Lewis structure and then answer questions 18 and 19. CF4 NCl3 CO2 18)Choose the correct statement by comparing the bonding around the central atom in each of the Lewis structures: a. In only one structure is there a lone pair of electrons around the central atom. b. In two structures there is a lone pair of electrons around the central atom c. In no structures is there a lone pair of electrons around the central atom d. In three structures there is a lone pair of electrons around the central atom 19)How many of the molecules have a dipole moment? a. 0 b. 1 c. 2 d. 3 Consider the following 3 molecules to answer questions 20 and 21: C2H2 C2H6 C2H4. 20)The Lewis structure for C2H4______________________________________. a. Contains a C-­‐-­‐-­‐C single bond and one lone pair on each of the carbon atoms. b. Contains a C-­‐-­‐-­‐C double bond with one lone pair on each of the carbon atoms. c. Contains a C-­‐-­‐-­‐C double bond with no lone pairs on the carbon atoms. d. Contains a C-­‐-­‐-­‐C triple bond with no lone pairs on the carbon atoms. 21)Which of the following statements about these molecules is correct? a. C2H2 has the strongest C-­‐-­‐-­‐C bond because it is the longest. b. C2H2 has the strongest C-­‐-­‐-­‐C bond because it is the shortest. c. C2H2 has the weakest C-­‐-­‐-­‐C bond because it is the shortest. d. C2H2 has the weakest C-­‐-­‐-­‐C bond because it is the longest. CHEM 102 Fall 2013 Exam 1A 5 Hunter College of the City University of New York Department of Chemistry & Biochemistry Extra Credit Question: (5 pts) NOTE: You must answer this question completely to receive credit (5 pts or nothing) NAME (Last name, First name):___________________________________________________________________________ EXAM VERSION:_____________________ As we have been seeing in class, scientists rely heavily on the development of models to explain how nature operates. As Chemists we develop models that describe the atomic and molecular behavior of matter in order to create images of nature in our minds that can explain that which we can see. Models are tricky – models that are simple are easiest to understand and sometimes explain complex phenomena but they fail to be accurate. Accurate models, however, are often so complex we cannot learn any general principles. So models are really about balancing accuracy with simplicity. Let’s analyze the particle diagrams we have used. Consider air. Air is a gas that is mostly nitrogen and a little oxygen. A chemistry student drew the following particle diagram representing air: ="Nitrogen" ="Oxygen" Use the table below to indicate 2 features of air that this diagram models accurately and 2 features of air that this model fails to model accurately. Features that the diagram models accurately Features that the diagram fails to model accurately 1. 2. 1. 2. CHEM 102 Fall 2013 Exam 1A 6 Hunter College of the City University of New York Department of Chemistry & Biochemistry This page was intentionally left blank CHEM 102 Fall 2013 Exam 1A 7 Hunter College of the City University of New York Department of Chemistry & Biochemistry This page was intentionally left blank CHEM 102 Fall 2013 Exam 1A 8 Hunter College of the City University of New York Department of Chemistry & Biochemistry This page was intentionally left blank CHEM 102 Fall 2013 Exam 1A 9 ...
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