MOCK FINAL Chemistry 102

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1 MOK FINAL hemistry When the following calculation is performed, how many significant figures are in the correct answer? ( ) x (6.022 x ) a) 1 b) 2 c) 3 d) 4 e) 6 2. ow many of the following formulas are written correctly? I. strontium(ii) chloride II. sulfur oxide III. bromine(iii) fluoride IV. potassium phosphide 3. Which of the following have both names and corresponding formulas correct? I. P 2 O 5 phosphorus pentoxide II. NilO 2 nickel(ii) hypochlorite III. RbNO 2 rubidium nitrate IV. ZnO 2 zinc oxide a) I and II b) I and III c) II and IV d) I, III, and IV e) none of the above 4. ow many mm 3 are in L? a) b) 35 c) 350 d) 35,000 e) 350, An isotope of an atom X has a mass number of 81. If the most stable ion of the isotope forms the compound MgX 2, how many neutrons does X have? a) 35 b) 45 c) 46 d) 70 e) Element Y has 15 protons. 31 Y 2- is isoelectronic with which atom below? a) Al b) P c) S d) l e) Ar

2 7. Rhenium has two isotopes, 185 Re and 187 Re, with an average atomic mass of amu. If Rhenium is 62.60% 187 Re, and the atomic mass of 187 Re is amu, what is the mass of 185 Re? a) amu b) amu c) amu d) amu 8. Fungal laccase is % u by mass. If one molecule contains 4 copper atoms, what is the molar mass of fungal laccase in g/mol? a) 99 b) 254 c) 652 d) 1.63 x 10 4 e) 6.52 x What is the mass of exactly 500 molecules of chloral hydrate, 2 3 l 3 O 2? a) 2.75 x b) 1.37 x g c) g d) g e) g 10. Adrenaline is %, 7.15 %, % O, and 7.65 % N by mass. What is its empirical formula? a) 9 13 NO 3 b) 12 4 N 5 O 7 c) 7 O 4 N d) 8 14 N 2 O ombustion of a compound of formula x y O z yields g 2 O and g O 2 when g of O 2 are used. If the molar mass of the compound is between 50 and 100 g/mol, what is the molecular formula of the compound? a) 5 8 O 3 b) 4 6 O 2 c) 4 3 O 4 d) 7 5 O hromium metal and elemental sulfur, S 8 (s), react to form chromium(iii) sulfide. If grams of product, which corresponds to a 76% yield, is obtained, what is the mass of S 8 used in the reaction, assuming no limiting reagent? (r = g/mol, S 8 = g/mol) a) g b) g c) g d) g 13. In the reaction N N 3, if 5 grams of each of the starting materials are used, the mass of unreacted reactant is a) 0 g b) 3.92 g c) 4.28 g d) 4.64 g

3 14. onsider the products of the following four unbalanced aqueous reactions: I. AgNO 3 (aq) + Kl (aq) II. (N 4 ) 2 SO 4 (aq) + Na 2 O 3 III. KO + Mnl 2 IV. Pb(NO 3 ) 2 + Bal 2 Which will result in the formation of a precipitate? a) I and II b) II and III c) III and IV d) I, II, and III e) I, III, and IV 15. Wet e is placed into a balloon at 24.4 and a pressure of mm g. What volume does this balloon occupy if the vapor pressure of water is 24.3 torr and the dried gas in the balloon weighs g? a) L b) L c) L d) 3.21 L e) L 16. Suppose the balloon in #18 is dipped in liquid nitrogen and cools down to If the balloon resizes to 23 ml, what is the new pressure inside the balloon? a) atm b) atm c) 5.48 atm d) 8.80 atm 17. At STP, the density of a gas is g/l. What is the identity of the gas? a) Ne b) l 2 c) Ar d) Kr e) Four 10 L flasks at STP contain Ar, e, 4, and F 2. Which of the following is TRUE regarding these? a) The average kinetic energy of Ar is the highest. b) Ar atoms have a higher velocity than F 2 molecules. c) 4 behaves more ideally than the other gases under these conditions. d) elium is the least dense. e) There are fewer moles of 4 than F A 4 L flask with 2.00 atm e is separated by a stopcock from a 2 L flask with 3.00 atm F 2. What is the total pressure once the stopcock is opened at constant T? a) atm b) 2.33 atm c) 5.00 atm d) 6.00 atm

4 20. A 4 L flask with 2.00 g e is separated by a stopcock from a 2 L flask with 3.00 g F 2. After the stopcock is opened, the total pressure is 600 mm g. What was the pressure of the helium inside the 4 L flask before it was opened? a) 900 mm g b) 777 mm g c) 518 mm g d) 400 mm g 21. Methane, 4, effuses times faster than another gas at the same temperature. What is the identity of the unknown gas? a) N 2 b) O 2 c) F 2 d) Ne e) Ar 22. What is the wavelength associated with light given off when the electron in a hydrogen atom jumps from n = 5 to n = 2? a) 435 nm b) -435 nm c) 145 nm d) 652 nm e) 3040 nm 23. ow many of the following are correct ground state electron configurations? r [Ar]4s 1 4d 5 Ge [Ar]4s 2 3d 10 4p 2 l + [Ne]3s 2 3p 8 Ta [Xe]6s 2 4f 10 5d Which of the following atoms/ions has the largest number of unpaired electrons in the ground state? (Assume that transition metals lose 4s electrons first). a) Mg b) Ar - c) u + d) Zn 2+ e) As ow many of the following quantum numbers correspond to a 4p electron? I. n = 4, l = 1, m l = -1 II. n = 4, l = 2, m l = 1 III. n = 4, l = 0, m l = 0 IV. n = 4, l = 1, m l = Which of the following has the smallest atomic radius? a) O b) Si c) Li d) s e) I

5 27. Which of the following is FALSE regarding ionization energy? a) < N b) < O c) P < S d) Na < Li e) K + < a 2+ I I X I I 28. Which of the atoms below could be X? a) N b) P c) O d) S e) l 29. Describe its shape and polarity: a) tetrahedral, nonpolar b) trigonal bipyramid, polar c) seesaw, polar d) square planar, nonpolar e) trigonal pyramid, polar 30. ow many of the following molecules are polar? 2 l 2 XeF 4 BrF 4 - PO What is the highest formal charge on ozone, O 3? a) -2 b) -1 c) 0 d) +1 e) An element in the ground state has one unpaired electron in the 5p atomic orbital. The element reacts with chlorine to form a neutral, covalent compound with 28 total valence electrons. Which of the following is this element? a) In b) Sn c) Sb d) Te e) I 33. What is the hybridization and shape for the central atom in IF 3? a) sp 3, trigonal planar b) sp 3, tetrahedral c) dsp 3, trigonal pyramidal d) dsp 3, T-shaped e) d 2 sp 3, trigonal pyramidal

6 l O * "A" * N O N "B" The structure shown to the left is loratadine, otherwise known as the allergy medicine laritin. 34. ow many π-bonds belong in the structure to the left? a) 5 b) 6 c) 7 d) 8 e) What are the bond angles A and B? a) 120, 120 b) 109, 109 c) 120, 109 d) 109, 120 e) 109, Rank the following in terms of increasing vapor pressure: F-F -F -Br Br-Br LiF F 4 a) LiF < F < Br < Br 2 < F 4 < F 2 b) F 2 < F 4 < Br 2 < Br < F < LiF c) F 2 < Br 2 < F 4 < F < Br < LiF d) Br 2 < F 4 < Br < F 2 < LiF < F 2 e) F < LiF < Br 2 < Br < F 2 < F ow many of the following list the strongest IMF for each compound? dipole-dipole BrF 3 LDF 2 S hydrogen bonding 2 Br 2 dipole-dipole N 3 -

7 38. Which of the following are possible resonance structures for azide, N 3 -? N N N N N N I. II. III. IV. N N N N N N a) I only b) II only c) IV only d) I and III e) II and III 39. onsider the following equilibrium reaction: (s) + O 2 (g) 2 O (g) Given the data at constant volume, below, which of the following statements about this equilibrium process is false? Temperature ( o ) % O 2 % O a) The reaction is endothermic b) The value of K is greater than 1 at all of the temperatures listed c) At 850 o, if the volume of the container is increased, the value of K increases d) The value of K at 1200 o is larger than the value of K at 950 o e) All of the above 40. onsider the following reaction in which all reactants and products are gases moles of A and 2.00 moles of B are placed in a 5.0 L container. After equilibrium has been established, 0.50 moles of D is present in the container. alculate the equilibrium constant, K, for this reaction. A (g) + 2 B (g) 2 (g) + D (g) a) 0.15 b) 0.33 c) 1.0 d) 3.0 e) none of these

8 41. ow many of the following will cause the equilibrium: (gr) + O 2 (g) 2 O (g) Δ o kj/mol to shift to the left? I. decreasing the volume II. adding more (gr) III. adding more O 2 (g) IV. removing O (g) as it forms V. raising the temperature 42. onsider the decomposition of ammonium chloride at a certain temperature: N 4 l (s) N 3 (g) + l (g) alculate the equilibrium constant, K, if the total pressure at equilibrium is 2.2 atm at that temperature. a) 1.1 b) 1.48 c) 2.20 d) 1.21 e) 4.84 The next 6 questions are True/False. There will not be True/False questions on the Final. 43. All exothermic reactions are spontaneous. 44. At constant volume, ΔE = q. 45. Doubling the coefficients of a balanced chemical reaction will double the Δ of the reaction. 46. The standard entropy of argon gas is greater than the standard entropy of O 2 (g). 47. The change in free energy (ΔG) for the process 2 O (s) 2 O (l) occurring at exactly 0 o is exactly equal to zero. 48. The enthalpy change for the reaction: N 2 (g) + O 2 (g) 2NO(g) is the same as the enthalpy change for the sum of the following reactions: N 2 (g) + O 2 (g) 2NO 2 (g) NO (g) + O 2 (g) NO 2 (g)

9 49. Suppose that L of an ideal, monatomic gas, has an initial pressure of 3.0 atm. It expands against a constant external pressure of 1.0 atm., until the volume is doubled. There is no exchange of heat between the system and the surroundings. alculate ΔE for this process. a) x 10 3 J b) +5.8 x 10 3 J c) x 10 3 J d) J e) J 50. For a particular process, q = -20 kj and w = 15 kj. Which of the following statements is true? a) eat flows from the system to the surroundings. b) The system does work on the surroundings. c) ΔE = -35 kj d) all of the above (a-c) are true. e) none of the above (a-c) are true ml of water was placed in a coffee cup calorimeter. The initial temperature was 21.6 o. One gram of ammonium nitrate was added to the water. After the solid dissolved, the final temperature of the solution was 20.5 o. The dissolving of this solid is a process: a) that has Δ < 0 b) that has ΔG > 0 c) that has ΔS universe < 0 d) that has ΔS < 0 e) none of the above (a-d) 52. Assuming that the heat capacity of the solution is the same as the heat capacity of water (4.184 J/g o ), calculate the Δ for the dissolution of ammonium nitrate and express it a kj/mol. (m.w. Ammonium Nitrate = 80 g/mol) a) kj/mol b) kj/mol c) kj/mol d) kj/mol e) kj/mol 53. onsider the reaction: 2 5 O (l) + 3O 2 (g) 2O 2 (g) + 2 O (l) When a 15.1 g sample of ethanol (MW = 46.1 g/mol) is burned, 4.49 x 10 2 kj of energy are released. ow much energy is released when 0.65 mol of ethanol are burned? a) 891 kj b) 1370 kj c) 2109 kj d) 89.7 kj e) 255 kj

10 54. For the combustion of ethanol as described in the equation above, which of the following statements is/are true? 1. The reaction is endothermic 2. The enthalpy change would be larger (more negative) if gaseous water were produced. 3. The reaction is an oxidation/reduction reaction. 4. The products of the reaction occupy a smaller volume than the reactants. a) 1,2 b) 2, 3, 4 c) 1, 3, 4 d) 3,4 e) only Estimate the N N bond energy given the following information: N N 3 Δ o = -92 kj N- bond energy = 391 kj/mol - bond energy = 432 kj/mol a) 1140 kj/mol b) 479 kj/mol c) 958 kj/mol d) 87 kj/mol e) 560 kj/mol Use the following information to answer the next four questions: (T = 25.0 o ) Reaction: l 2 (aq) + 2I - (aq) 2l - (aq) + I 2 (s) Species ΔG o Initial oncentration l 2 (aq) 6.9 kj/mol 1.00 x 10-4 M I - (aq) kj/mol 1.00 x 10-4 M l - (aq) kj/mol M 56. What is ΔG o for the reaction, expressed in kj/mol? a) b) c) d) e) What is ΔG for the reaction at the given initial concentrations, in kj/mol? a) b) c) d) e) Beginning with the given initial concentrations, the reaction would proceed to form more: a) l 2 and l - b) I 2 and l 2 c) l 2 and I - d) l - and I 2 e) the reaction is at equilibrium

11 59. alculate K the equilibrium constant for the reaction: a) 67.1 b) 1.24 x c) 7.33 x d) 8.2 x e) 1.42 x Rank the 4 species found in this reaction in order of increasing absolute entropy. a) l 2 < I - < l - < I 2 b) I 2 < l 2 < I - < l - c) I 2 < l 2 < l - < I - d) I 2 < l - < I - < l 2 e) l 2 < I 2 < l - < I -

CHM 151 Practice Final Exam

CHM 151 Practice Final Exam CM 151 Practice Final Exam 1. ow many significant figures are there in the result of 5.52 divided by 3.745? (a) 1 (b) 2 (c) 3 (d) 4 (e) 5 2. ow many significant figures are there in the answer when 9.021