sp2010ex2f4 - General Chemistry II D‐1 11/17/2009 Name

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Unformatted text preview: General Chemistry II D‐1 11/17/2009 Name _______________________________ Choose the best answer from the ones provided MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Use the standard reaction enthalpies given below to determine ΔH°rxn for the following reaction: P4 (g) + 10 Cl 2 (g) → 4PCl 5 (s) Given: PCl5 (s) → PCl3 (g) + Cl2 (g) P4 (g) + 6 Cl2 (g) → 4 PCl3 (g) A) - 1364 kJ B) - 1050. kJ ΔH°rxn= +157 kJ ΔH°rxn = - 1207 kJ C) - 1835 kJ D) - 1786 kJ E) - 2100. kJ 2) ΔH°rxn = ? 1) Examination III Dr. Lopez de la Vega form 4 2) Calculate the amount of heat (in kJ) required to raise the temperature of a 79.0 g sample of ethanol from 298 K to 385 K. The specific heat capacity of ethanol is 2.42 J/g°C. A) 57.0 kJ B) 12.9 kJ C) 16.6 kJ D) 73.6 kJ E) 28.4 kJ 3) A 0.465 g sample of an unknown compound occupies 245 mL at 298 K and 1.22 atm. What is the molar mas s of the unknown compound? A) 81.8 g/mol B) 26.3 g/mol C) 33.9 g/mol D) 38.0 g/mol E) 12.2 g/mol 4) What pressure will 2.6 x 10 23 molecules of H2 exert in a 3.9 L container at 45°C? A) 5.7 atm B) 3.4 atm C) 2.9 atm D) 4.6 atm E) 1.7 atm 3) 4) 5) How many liters of a 0.0550 M KCl solution contain 0.163 moles of KCl? A) 1.12 L B) 3.37 L C) 1.48 L D) 8.97 L 5) E) 2.96 L 6) 6) Determine the theoretical yield of HCl if 60.0 g of BCl 3 and 37.5 g of H 2 O are reacted according to the following balanced reaction. A possibly useful molar mass is BCl 3 = 117.16 g/mol. BCl3 (g) + 3 H 2 O(l) → H3 BO3 (s) + 3 HCl(g) A) 56.0 g HCl B) 187 g HCl C) 132 g HCl D) 75.9 g HCl E) 25.3 g HCl 7) Give the net ionic equation for the reaction (if any) that occurs when aqueous solutions of Na2 CO 3 and HCl are mixed. A) 2 Na+ (aq) + CO3 2 - (aq) + 2 H+ (aq) + 2 Cl - (aq) → H2 CO 3 (s) + 2 NaCl(aq) B) 2 H + (aq) + CO3 2 - (aq) → H2 CO 3 (s) C) 2 Na+ (aq) + CO3 2 - (aq) + 2 H+ (aq) + 2 Cl- (aq) → H2 CO 3 (s) + 2 Na+ (aq) + 2 Cl- (aq) D) 2 H + (aq) + CO3 2 - (aq) → H2 O(l) + CO2 (g) E) No reaction occurs. 7) D‐1 form 4 D‐2 8) Which of the following samples will have the greatest average speed at 355 K? A) Cl2 B) C2 H4 C) CH4 D) Ne E) All of these samples will have the same average speed at the same T. 9) Use the information provided to determine ΔH°rxn for the following reaction: CH4 (g) CHCl3 (l) HCl(g) A) +117 kJ ΔH°f (kJ/mol) ΔH°rxn= ? - 75 - 134 - 92 B) - 151 kJ C) +662 kJ D) - 217 kJ E) - 335 kJ 10) CH4 (g) + 3 Cl2 (g) → CHCl3 (l) + 3 HCl(g) 9) 8) 10) How many molecules of CO 2 are contained in a 10.0 L tank at 7.53 atm and 485 K? A) 1.89 × 1024 molecules B) 8.32 × 1024 molecules C) 4.89 × 1024 molecules D) 3.63 × 1024 molecules E) 1.14 × 1024 molecules 11) Calculate the change in internal energy ( ΔE) for a system that is absorbing 35.8 kJ of heat and is expanding from 8.00 to 24.0 L in volume at 1.00 atm. (Remember that 101.3 J = 1 L·atm) A) - 15.8 kJ B) +51.8 kJ C) - 16.6 kJ D) - 29.3 kJ E) +34.2 kJ 11) 12) Determine the oxidation state of Sn in Sn(SO 4 )2 . A) +4 B) 0 C) - 2 D) +2 E) +6 12) 13) How much energy is required to decompose 765 g of PCl 3 , according to the reaction below? The molar mass of PCl3 is 137.32 g/mol and may be useful. 4 PCl 3 (g) → P4 (s) + 6 Cl2 (g) A) 1.68 × 103 kJ B) 4.33 × 103 kJ C) 6.72 × 103 kJ D) 2.31 × 103 kJ E) 5.95 × 103 kJ 14) What mass of NO 2 is contained in a 13.0 L tank at 4.58 atm and 385 K? A) 86.7 g B) 53.1 g C) 18.8 g D) 69.2 g E) 24.4 g ΔH°rxn = +1207 kJ 13) 14) D‐2 form 4 D‐3 15) A mixture of 0.220 moles CO, 0.350 moles H 2 and 0.640 moles He has a total pressure of 2.95 atm. What is the pressure of CO? A) 0.536 atm B) 0.649 atm C) 0.955 atm D) 1.86 atm E) 1.54 atm 16) 15) 16) Determine the theoretical yield and the percent yield if 21.8 g of K 2 CO 3 is produced from reacting 27.9 g KO2 with 29.0 L of CO 2 (at STP). The molar mass of KO 2 = 71.10 g/mol and K 2 CO 3 = 138.21 g/mol. 4 KO 2 (s) + 2 CO 2 (g) → 2 K 2 CO 3 (s) + 3 O 2 (g) A) 27.1 g, 80.4 % yield B) 179 g, 12.2 % yield C) 61.0 g, 35.7 % yield D) 91.7 g, 23.8 % yield E) 206 g, 10.6 % yield 17) Which of the following signs on q and w represent a system that is doing work on the surroundings, as well as gaining heat from the surroundings? A) q = - , w = + B) q = - , w = C) q = +, w = + D) q = +, w = E) None of these represent the system referenced above. 18) According to the following thermochemical equation, what mass of HF (in g) must react in order to produce 345 kJ of energy? Assume excess SiO 2 . SiO2 (s) + 4 HF(g) → SiF4 (g) + 2 H 2 O(l) A) 42.7 g B) 37.5 g C) 173 g ΔH°rxn = - 184 kJ D) 107 g E) 150. g 17) 18) 19) According to the following reaction, how many grams of sulfur are formed when 37.4 g of water are formed? 2 H 2 S(g) + SO2 (g) → 3 S(s) + 2H2 O(l) A) 99.8 g S B) 44.4 g S C) 14.0 g S D) 66.6 g S E) 56.1 g S 19) 20) Two aqueous solutions are both at room temperature and are then mixed in a coffee cup calorimeter. The reaction causes the temperature of the resulting solution to fall below room temperature. Which of the following statements is TRUE? A) Energy is leaving the system during reaction. B) This type of experiment will provide data to calculate ΔErxn. C) The products have a lower potential energy than the reactants. D) The reaction is exothermic. E) None of the above statements are true. 20) D‐3 form 4 D‐4 21) Determine the limiting reactant (LR) and the mass (in g) of nitrogen that can be formed from 50.0 g N2 O4 and 45.0 g N2 H4 . Some possibly useful molar masses are as follows: N 2 O4 = 92.02 g/mol, N2 H4 = 32.05 g/mol. N2 O4 (l) + 2 N2 H4 (l) → 3 N2 (g) + 4 H 2 O(g) A) LR = N2 O4 , 105 g N 2 formed B) LR = N2 H4 , 13.3 g N2 formed C) LR = N2 H4 , 59.0 g N2 formed D) LR = N2 O4 , 45.7 g N2 formed E) No LR, 45.0 g N 2 formed 22) The titration of 25.0 mL of an unknown concentration H 2 SO4 solution requires 83.6 mL of 0.12 M LiOH solution. What is the concentration of the H 2 SO4 solution (in M)? A) 0.36 M B) 0.10 M C) 0.20 M D) 0.40 M E) 0.25 M 23) 22) 21) 23) Which of the following statements is TRUE? A) Cars that run on hydrogen fuel cells are environmentally friendly. B) The burning of fossil fuels contributes to global warming. C) Acid rain is one of the problems associated with the combustion of fossil fuels. D) The more energy produced per kg of CO 2 produced, the better the fuel. E) All of the above are true. 24) What volume (in L) of 0.0887 M MgF 2 solution is needed to make 275.0 mL of 0.0224 M MgF 2 solution? A) 69.4 mL B) 10.9 mL C) 91.8 mL D) 14.4 mL E) 72.3 mL 24) 25) What is the form number listed at the top of the exam. A) Form I or Form A B) Form II or Form B C) Form III or Form C D) Form IV or Form D E) Form V or Form E 25) D‐4 Answer Key Testname: UNTITLED1 1) C 2) C 3) D 4) C 5) E 6) A 7) D 8) C 9) E 10) E 11) E 12) A 13) A 14) A 15) A 16) A 17) D 18) E 19) A 20) E 21) D 22) C 23) E 24) A 25) No Correct Answer Was Provided. D‐5 ...
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