102-F14-Exam-TF-1A-F14 - Hunter College of the City University of New York Department of Chemistry Biochemistry CHEM 102 General Chemistry I Fall 2014

102-F14-Exam-TF-1A-F14 - Hunter College of the City...

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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 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 31 questions (7 pages). Each question is worth 6.67 points. There are a total of 206.77 points on this exam. 200 points is full credit. 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 (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 2014 Exam 1A 1 Hunter College of the City University of New York Department of Chemistry & Biochemistry Multiple Choice Questions: (6.67 pts each) 1) Which group best illustrates the transition from non-­‐metallic to metallic behavior with increasing atomic number? a. Be, Mg, Ca, Sr b. B, Al, Ga, In c. F, Cl, Br, I d. Fe, Ru, Os, Hs Model A Model B 2) Methane (CH4) is a gas at room temperature but routinely cooled to the liquid state for transport. This is called liquefied natural gas (LNG). To the right are shown are two models of LNG. Read the three statements below about Model B and select the CORRECT choice. I. Model B should never be used because it doesn’t show the atoms of methane. II. Model B is a simple model of LNG demonstrating that the liquid phase is disordered. III. Model B might be a better model of the LNG than model A if only the disorder and density of the liquid phase is desired. a. Only answer I is correct. b. Only answer II is correct. c. Only answer III is correct. d. Answers II and III are correct. 3) Bill Gates net worth is estimated at $76 billion. My net worth when I was a student was estimated to be $100. Bill Gates’ net worth is about how many orders of magnitude (10x) greater than mine? a. x=5 b. x=7 c. x=9 d. x=11 4) A particularly fine variety of cheese is sold for $1.47 per ounce. How much would you pay to purchase 1 kg of this cheese? (1 ounce = 28.35 grams) a. $51.85 b. $41.67 c. $5. 19 d. $0.41 CHEM 102 Fall 2014 Exam 1A 2 Hunter College of the City University of New York Department of Chemistry & Biochemistry 5) The acceleration due to gravity near the earth’s surface is 9.81 m/s2. This means that the speed of a falling object will increase by 9.81m/s for every second that it falls. What is the acceleration due to gravity measured in units of ft/hr2? (1 foot = 12 inches; 1 inch = 0.0254 m) a. 32.2 ft/h2. b. 1.16x105 ft/hr2 c. 4.17x108 ft/hr2 d. 2.48x10-­‐6 ft/hr2 6) A very large unit of measurement is the zettameter (zm). 1 zm = 1021 m, but astronomers measures distances in even bigger units called astronomical units (the au). One au is defined to be approximately 107 miles (the average distance between the center of the earth and the center of the sun). An even bigger unit is called the parsec, which is equal to about 2x105 au. When astronomers talk about intergalactic space however it’s even more convenient to use units of kiloparsecs. Given that 1.6 km = 1 mile, about how many kiloparsecs are there in a zettameter? a. 1/3 x 10-­‐6 kiloparsecs b. 1/3 x 10-­‐3 kiloparsecs c. 1/3 x 103 kiloparsecs d. 1/3 x 106 kiloparsecs 65 7) How many protons, neutrons and electrons are in the Zn-­‐65 isotope? 30 a. 65 p, 30 n and 35 electrons b. 65 p, 30 n and 30 electrons c. 30 p, 35 n and 30 electrons d. 30 p, 30 n and 5 electrons 8) What is the sum of the protons in all of the atoms of the molecule dinitrogen pentoxide. a. 54 b. 46 c. 40 d. 34 9) 1s22s22p63s23p64s23d6 is the correct electron configuration for which of the following atoms? a. Se b. Te c. Fe d. Ru 10)How many of the following elements are diamagnetic? Ca As Cu Fe Cd a. 1 b. 2 c. 3 d. 4 Zn CHEM 102 Fall 2014 Exam 1A 3 Hunter College of the City University of New York Department of Chemistry & Biochemistry 11)The interaction of a single electron with a nucleus of a +2 charge is _____ __________ than the interaction of a single electron with a nucleus of a +3 charge. a. less attractive b. more attractive c. less repulsive d. more repulsive 12)What is the correct chemical formula for the ionic compound that forms when barium (Ba) combines with nitrogen (N)? a. Ba2N3 b. Ba3N2 c. BaN2 d. BaN 13)Which of the following names is not matched with the correct formula? a. NO3, nitrate b. NaNO3, sodium nitrate c. CrO3, chromium(VI) oxide d. Cl2F7, dichlorine heptafluoride 14)What is the correct name for Mn(SO4)2? a. Manganese (IV) sulfate b. Manganese (IV) sulfite c. Manganese (II) sulfate d. Manganese (II) sulfite 15)What is the correct formula for molybdenum(V) phosphate? a. Mo2(PO4)5 b. Mo3(PO4)5 c. Mo5(PO4)3 d. Mo5(PO4)2 16)What is the correct ground state electron configuration for the Ni2+ cation? a. [Ar]4s23d8 b. [Ar]3d8 c. [Ar]4s23d10 d. [Ar]4s23d6 CHEM 102 Fall 2014 Exam 1A 4 Hunter College of the City University of New York Department of Chemistry & Biochemistry 17)Given the electronegativity values below, which of the following covalent single bonds is the most polar? Element Electronegativity a. C-­‐H H 2.1 b. N-­‐H C 2.5 c. O-­‐H N 3.0 d. O-­‐C O 3.5 e. O-­‐N 18)Which of the following statements about the Lewis Structure for SF2 is CORRECT? a. The central sulfur atom has one single bond and one double bond b. The central sulfur atom has two double bonds c. The central sulfur atom has 1 lone pair of electrons d. The central sulfur atom has 2 lone pairs of electrons 19)Which of the following Lewis structures is a valid representation of the POCl molecule? O# P# Cl# O# P# Cl# O# P# Cl# O# P# Cl# a. b. c. d. 20)Of the following bonds: C"""N" C"""N"and , the C"""N"bond is the _________ and ____________. , C"""N" a. strongest, shortest b. strongest, longest c. weakest, shortest d. weakest, longest 21)When an aqueous solution of cobalt(VI) chloride reacts with an aqueous solution of lead(II) nitrate the reaction produces solid lead(II) chloride and aqueous cobalt (VI) nitrate. The coefficient in front of the lead(II) chloride in the balanced chemical equation is a. 1 b. 2 c. 3 d. 4 22)How many molecules of O2 are required for the complete combustion of 5 molecules of C3H8 to form CO2 and H2O according to the equation: C3H8 (g) + 5O2 (g) è 3CO2 (g) + 4H2O (g) a. 50 b. 25 c. 15 d. 5 CHEM 102 Fall 2014 Exam 1A 5 Hunter College of the City University of New York Department of Chemistry & Biochemistry 23)The ΔH for the reaction 2H2 + O2 à 2H2O is -­‐483 kJ. The ΔH for this reaction is a. exothermic and the temperature of the surroundings will go up b. endothermic and the temperature of the surroundings will go up c. exothermic and the temperature of the surroundings will go down d. endothermic and the temperature of the surroundings will go down Problems 24-­‐27 Let’s study the decomposition of aluminum oxide at room temperature to produce aluminum and diatomic oxygen. Aluminum oxide is typically how aluminum is mined from Earth as an ore. Then, through a specific process called the Hall-­‐Heroult process, the oxide is decomposed into pure aluminum metal that is made into the aluminum cans and foil that we know so well. Answer the following questions about this process. 24)Based on the balanced chemical equation, the ratio of the stoichiometric coefficients of the aluminum oxide to oxygen (aluminum oxide: oxygen) is: a) 1:1 b) 1:3 c) 2:3 d) 3:2 25)The phases or states of the matter in the balanced chemical equation for the aluminum oxide, the aluminum metal, and the oxygen, in that order, are: a) gas, solid, gas b) solid, liquid, gas c) solid, gas, solid d) solid, solid, gas 26)The decomposition of the aluminum oxide involves mostly the breaking of bonds although the formation of oxygen involves the making of an oxygen-­‐oxygen double bond. We can therefore say that this reaction is: a) exothermic because the reaction involves mostly the breaking of bonds. b) endothermic if the broken bonds are stronger than the formed bonds. c) exothermic if the broken bonds are stronger than the formed bonds. d) endothermic if the broken bonds are weaker than the formed bonds. 27)For every eight dozen atoms of aluminum produced, you need to mine how many dozen aluminum oxide ore units? a) 4 dozen b) 3 dozen c) 2 dozen d) 1 dozen CHEM 102 Fall 2014 Exam 1A 6 Hunter College of the City University of New York Department of Chemistry & Biochemistry 28)Which of the following statements about an endothermic reaction is INCORRECT. a. The temperature of the surrounding decreases. b. Energy flows from the surroundings into the system c. The potential energy change for the reaction is positive. d. The products have a lower energy that the reactants 29)Hydrogen peroxide H2O2 decomposes to give H2O and O2, What is the minimum number of hydrogen peroxide molecules you need to produce 3 oxygen molecules? a. 2 b. 3 c. 4 d. 6 30)Imagine that the hydrogen peroxide decomposes according to the reaction in #29. 214 kJ of energy is released for every mol of oxygen produced. Using the table of bond energies below determine the bond energy of the O-­‐O single bond in H2O2? a. 284 kJ/mol Bond type Bond energy (kJ/mol) b. 142 kJ/mol c. 712 kJ/mol O-­‐H 463 d. 356 kJ/mol O=O 498 31) Consider the 3 p orbitals shown to the z z z right. Sulfur has the electron configuration [Ne]3s23p4. The four p y y y electrons are best described in which p orbitals: x x a. 2 in px, 1 in py, 1 in pz pz# x px# py# b. 2 in px, 2 in py c. 3 in px and 1 in py d. 4 in px CHEM 102 Fall 2014 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 2014 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 2014 Exam 1A 9 Hunter College of the City University of New York Department of Chemistry & Biochemistry This page was intentionally left blank CHEM 102 Fall 2014 Exam 1A 10 ...
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