2015 Academic Challenge

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1 2015 Academic hallenge EMISTRY TEST SETIONAL This Test onsists of 40 Questions hemistry Test Production Team Iffat Ali, Lake Land ollege Author/Team Leader Nancy arter Dopke, Alma ollege Reviewer Kathryn Torrey, WYSE oordinator of Test Production GENERAL DIRETIONS Please read the following instructions carefully. This is a timed test; any instructions from the test supervisor should be followed promptly. The test supervisor will give instructions for filling in any necessary information on the answer sheet. Most Academic hallenge sites will ask you to indicate your answer to each question by marking an oval that corresponds to the correct answer for that question. One oval should be marked to answer each question. Multiple ovals will automatically be graded as an incorrect answer. If you wish to change an answer, erase your first mark completely before marking your new choice. You are advised to use your time effectively and to work as rapidly as you can without losing accuracy. Do not waste your time on questions that seem too difficult for you. Go on to the other questions, and then come back to the difficult ones later if time remains. *** Time: 40 Minutes *** DO NOT OPEN TEST BOOKLET UNTIL YOU ARE TOLD TO DO SO! 2015 Worldwide Youth in Science and Engineering WYSE, Worldwide Youth in Science and Engineering and the WYSE Design are service marks of and this work is opyright 2015 by the Board of Trustees of the University of Illinois at Urbana hampaign. All rights reserved

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3 Periodic Table of the Elements *Lanthanides **Actinides 1A 2A 3A 4A 5A 6A 7A 8A 19 K a Rb Sr s Ba Li Be Na Mg Fr (223) 88 Ra Sc Ti V r Mn Fe o Ni u Zn Y Zr Nb Mo Tc (98) 44 Ru Rh Pd Ag d La* f Ta W Re Os Ir Pt Au g Unq 105 Unp 106 Unh 107 Uns 108 Uno 109 Une 89 Ac** (227) 31 Ga In Tl B Al Ge Sn Pb Si As Sb Bi N P Se Te Po (209) 8 O S Br I At (210) 9 F l e Kr Xe Rn (222) 10 Ne Ar e Pr Nd Pm (145) 62 Sm Eu Gd Tb Dy o Er Tm Yb Lu Th Pa (231) 92 U Np (237) 94 Pu (244) 95 Am (243) 96 m (247) 97 Bk (247) 98 f (251) 99 Es (252) 100 Fm (257) 101 Md (258) 102 No (259) 103 Lr (260)

4 Potentially Useful Information q = m c s T T b = i K b m P solvent = solvent P solvent ln ( [A] t [A] 0 ) = kt [A] t [A] 0 = kt T f = i K f m S gas = k P gas k = Ae Ea/RT 1 1 = kt [A] t [A] 0 ln ( k 2 k 1 ) = E a R ( 1 T 2 1 T 1 ) ln ( K 2 ) = rxn ( 1 1 ) ln ( P 2 ) = vap ( 1 1 ) K 1 R T 2 T 1 P 1 R T 2 T 1 p = -log [ 3O + ] po = -log [O - ] p = pk a + log ( [A ] [A] ) G = - T S Ssurr = sys T E cell = E red + E ox E = B ( 1 n f 2 1 n i 2 ) G = -nf = MRT x= -b ± b 2-4ac 2a c = E = h F = /mol K w = R = L atm/mol K; J/mol K B = -2.18x10-18 J 1.0 kg = 2.2 lb N A = 6.022x in = 2.54 cm 1 atm = 101,325 Pa = bar 1 lb = g 1 J = 1 N m = 1 kg m 2 s -2 = cal c = m/s h = x J s Assume all gases behave ideally unless specifically told to do otherwise Assume all solutions are aqueous and at 25 unless specifically told otherwise Assume all gases are at STP unless specifically told otherwise Simple Rules for the Solubility of Salts in Water 1. Most nitrates are soluble 2. Most salts containing Group 1 ions or ammonium (N 4+ ) are soluble 3. Most chloride, bromide, and iodide salts are soluble except those of Ag +, Pb 2+, and g Most sulfates are soluble with the exception of Ba 2+, Pb 2+, g 2 2+, and a Most hydroxide salts are only slightly soluble with the exception of Group 1 hydroxides. Group 2 (Ba 2+ to a 2+ ) are slightly soluble. 6. Most sulfides, carbonates, chromates, and phosphates are only slightly soluble.

5 hemistry - 1 WYSE Academic hallenge hemistry Test (Sectional) A company is going to expand and is considering buying a plot of land in Europe. If it wants to have an area of 2.50 square miles, about how much land should it buy, in units of square kilometers, if 1 mile = kilometers? A km 2 B km km 2 D km 2 E km 2 2. What is the final temperature of 15.0 g of water in a glass at 22.0 when joules of heat are added? (onsider all energy has been successfully transferred to water and the specific heat capacity of water is J/g.) A. 7.0 B D E The structural formulas of the hydrocarbons 3 3 and are presented below. These species belong to a series known as. A. isotopes B. allotropes. homologs D. isomers E. isobars 4. What type of reaction is shown below? u 2+ (aq) + SO 4 2 (aq) + 2 Na + (aq) + S 2 (aq) 2 Na + (aq) + SO 4 2 (aq) + us(s) A. precipitation B. hydration. neutralization D. oxidation-reduction E. combustion 5. A compound contains 36.86% N and 63.14% O by mass. What is its empirical formula of this compound? A. NO B. NO 2. N 2O D. NO 3 E. N 2O 3 6. A gaseous solution is made up of moles of nitrogen gas and moles of oxygen gas. What are the mole fractions of nitrogen and oxygen in that order? A and B and and D and E and 0.433

6 hemistry What is the mass percent of hydrogen in ethanol, 3 2O? A B D E Suppose 26.0 g of calcium chloride, al 2, are dissolved in water to make ml of solution. ow many times greater is the molarity of chloride ions (l ) than the molarity of calcium ions (a 2+ ) in the solution? A B D E Which of the following half reactions displays the greatest ease in oxidation with the associated potentials? A. Mg e Mg; E = 2.37 V B. F e 2 F ; E = 2.87 V. Ag + + e Ag; E = 0.80 V D. Al e Al; E = 1.66 V E e 2; E = 0.00 V 10. Which of the following has a trigonal planar geometry? A. O 2 B. O. 4 D. 2O E. N Which one is the correct distribution of subatomic particles in atoms? Inside the nucleus Outside of the nucleus A. Neutrons and electrons Protons B. Protons and electrons Neutrons. Protons and neutrons Electrons D. Electrons Protons and neutrons E. Neutrons Electrons and protons 12. Which of these is the electron configuration of the chloride ion (l )? A. [Kr] 5s 2 B. 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6. 1s 2 2s 2 2p 6 3s 2 3p 6 D. 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 5s 2 E. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 4p By definition, the rare-earth elements are elements with a partially filled orbital. A. p B. d. s D. f E. g 14. What is the po of an acid if its [ + ] is M? A B D E. 2.50

7 hemistry Which of the following represents the properly balanced chemical equation for the word equation below? iron(ii) sulfide + hydrochloric acid iron(ii) chloride + dihydrogen sulfide A. FeS + l Fel 2 + 2S B. Fe 2S + 2 l Fe 2l 2 + 2S. 2 FeS + 4 l 2 Fel S D. FeS + 2 l Fel 2 + 2S E. 2 Fe 2S + 2 l 2 Fe 2l 2 + 2S 16. Knowing the fact that carbon dioxide, O 2, is an acidic anhydride, the p of the natural rain water is expected to be. A. equal to zero B. around equal to 7 D. greater than 7 E. less than Predict the direction in which the following equilibrium will shift if the pressure on the system is decreased by expansion. lf 5(g) lf 3(g) + F 2(g) A. Equilibrium will shift to the right. B. Equilibrium will shift to the left.. It cannot be predicted, because it depends on a catalyst. D. The pressure on the system has no effect on the equilibrium. E. It is not possible to predict without additional information. 18. Which of the following describes the ionization energy trend through the periodic table? In a period in a column A. increases from left to right decreases from top to bottom B. increases from left to right increases from top to bottom. decreases from left to right decreases from top to bottom D. decreases from left to right increases from top to bottom E. remains unchanged remains unchanged 19. What is the bond angle of the -S- bond in 2S molecule? A. ~90 B. ~180. ~120 D. ~109.5 E. ~45

8 hemistry The rate law of the following reaction is expressed on its right. Which of the answers is incorrect? A + B + products Rate = k[b][] 2 A. The reaction is zero order with respect to A B. The reaction is first order with respect to B. The reaction is second order with respect to D. The reaction overall is a second order E. The reaction overall is a third order 21. Which of the following has bond angles of 109.5? A. Sel 4 B. XeF 4. SiF 4 D. SF 4 E. SO A sample of 1.00 mole of chlorine gas, l 2, is in a steel tank at 40.0 and mmg pressure. What is the density of the chlorine gas? A g/l B g/l g/l D g/l E g/l 23. In the following reaction, what would take place at the anode? A. 2 Ag + (aq)+ 2 e 2 Ag(s) B. u 2+ (aq) + 2 e 2 Ag(s). u(s) u 2+ (aq) + 2 e D. u(s) 2 Ag + (aq)+ 2 e E. 2 Ag + (aq) u 2+ (s) u(s)+ 2 Ag + (aq) u 2+ (aq) + 2 Ag(s) 24. The best description of an isotope A. Isotopes have the same number of protons and neutrons. B. Isotopes have the same number of protons, but have different numbers of neutrons.. Isotopes are chemically identical, but they differ in mass. D. Isotopes have the same mass but they differ in chemical behavior. A. A & B B. A & D. & D D. B & E. B & D 25. What is the enthalpy change for the following reaction? 8 18(l) + 12½ O 2(g) 8 O 2(g) + 9 2O(g) rxn = Σmol f o prod Σmol f o react Δºf of 818(l) = kj Δºf of O2(g) = kj Δºf of 2O(g) = kj A kj B kj kj D kj E kj

9 hemistry Which chemical name does not match with the formula given in the following table? Name Formula Sodium sulfite Na 2SO 4 Magnesium nitride Mg 3N 2 Iron(II) phosphate Fe 3(PO 4) 2 Dichlorine pentoxide l 2O 5 Dinitrogen tetroxide N 2O 4 A. Sodium sulfite B. Magnesium nitride. Iron(II) phosphate D. Dichlorine pentoxide E. Dinitrogen tetroxide 27. Identify the correct statement from the following table. ΔGº (kj) Δº (kj) Reaction-I Reaction-II A. Reaction-I is spontaneous and exothermic B. Reaction-II is spontaneous and exothermic. Reaction-I is spontaneous and endothermic D. Reaction-I is nonspontaneous and exothermic E. Reaction-II is nonspontaneous and exothermic 28. Ethylene ( 2 4) reacts with bromine gas according to the following equation: 2 4(g) + Br 2(g) 2 4Br 2(g) The rate of this reaction is first order in [ 2 4] and third order overall. If the initial concentrations of the reactants are doubled, the rate of the reaction will increase by what factor? A. 2 B D. 8 E Thallium-201 is a radioactive isotope that undergoes first-order decay. When the concentration of 201 Tl is M, its half-life is 73.0 hours. What is the half-life of 201 Tl when its concentration is M? A hours B hours. 123 hours D. 236 hours E hours 30. If a drop of water is subdivided till the smallest piece that retains the chemical and physical properties of water, it will be a(an). A. mixture B. molecule. atom D. anion E. cation

10 hemistry Which of the following is true for the osmotic pressure of 0.10 M solutions of Nal and Mgl 2 at 25 º? A. Osmotic pressure of both solutions will be the same. B. Osmotic pressure of 0.10 M Nal will be lower than that of 0.10 M Mgl 2.. Osmotic pressure of 0.10 M Nal will be higher than that of 0.10 M Mgl 2. D. Osmotic pressure depends on how the solution is prepared. E. Osmotic pressure is independent of concentration when the temperature is the same. 32. A mixture of iron, salt and sand can be separated using a magnet, water, a filter paper, and a hot plate. The separation of this mixture. A. uses chemical and physical changes or processes B. uses physical changes/processes. uses chemical changes/processes D. uses precipitation process E. cannot be done with the materials listed 33. Gold ions react with copper metal to give gold metal and cupric ions. 2 Au 3+ (aq) + 3 u(s) 2 Au(s) + 3 u 2+ (aq) What is the equilibrium expression for this reaction? A. K = [Au 3+ ] 2 /[u 2+ ] 3 B. K = [Au] 2 [u 2+ ] 3 /[Au 3+ ] 2 [u] 3. K = [Au 3+ ] 2 [u] 3 /[Au] 2 [u 2+ ] 3 D. K = [u 2+ ] 3 /[Au 3+ ] 2 E. K = [Au] 3 [u 2+ ] 2 /[Au 3+ ] 3 [u] Within a period, what happens to the size of an atom as the atomic number increases? A. Size does not change. B. The atom gets smaller.. The atom gets larger. D. The atom breaks down. E. There is no relationship. 35. Which one of the following is true when a small amount of acid is added to pure water and a buffered water solution? Pure water Buffered water A. p increases drastically p increases drastically B. p decreases drastically p decreases drastically. p increases significantly p decreases significantly D. p remains nearly unchanged p remains nearly unchanged E. p decreases drastically p remains nearly unchanged

11 hemistry Suppose 0.10 moles of the compound AB 2 are dissolved in 1.0 kg of water. In this solution, AB 2 ionizes completely. Which of the following is the correct molality for A and B? A. The molality of A is 0.20 mol/kg and the molality of B is 0.10 mol/kg. B. The molality of A is 0.10 mol/kg and the molality of B is 0.20 mol/kg.. The molality of A is 0.10 mol/kg and the molality of B is 0.10 mol/kg. D. The molality of A is 0.20 mol/kg and the molality of B is 0.20 mol/kg. E. The molality of A is 0.40 mol/kg and the molality of B is 0.20 mol/kg. 37. If the frequency of light required for moving an electron from a lower energy to a higher is 1.11 x s 1. What is the corresponding change in energy ( E)? A x J B x J x J D x J E x J 38. A tank of gas is found in the coldest part of the refrigerator (at 0 ). It contains 1 mole of oxygen and 3 moles of neon gases. The volume of the tank is 11.2 L. What is the partial pressure of oxygen in the tank? A atm B atm. 2.0 atm D. 8.0 atm E. 4.0 atm 39. In the proposed reaction mechanism below, which of the following is an intermediate? l 3(g) + l 2(g) l(g) + l 4(g) (overall) Step 1: l 2(g) 2 l (g) fast Step 2: l (g) + l 3(g) l(g) + l 3 (g) slow Step 3: l 3 (g) + l (g) l(g) + l 4(g) fast A. l B. l 3. l 4 D. l 3 E. l A sample of argon gas occupies 3.8 L at 83 º and 4.25 atm. What will the new volume be if the conditions are changed to 52 and 1.75 atm? A. 5.8 L B. 4.1 L. 3.5 L D. 9.2 L E. 8.4 L