Version B UNIVERSITY OF VICTORIA CHEMISTRY 102 Midterm Test 2 March 14, 2014 5-6 pm (60 minutes) Version B DISPLAY YOUR STUDENT ID CARD ON THE TOP OF YOUR DESK NOW Answer all multiple choice questions on the bubble sheet provided. Use a soft pencil. The scanner does not read ink. Complete the identification portion of the bubble sheet according to the example shown. (The student’s name in the example is Bab Cabba.) Hand in only the bubble sheet at the end of the test period (60 minutes). A DATA sheet is included, unstapled, inside the cover page of this test. This test has 9 pages (not including the DATA sheet). Count the pages before you begin. The basic Sharp EL510 calculator or the Sharp EL-510 RNB are the only ones approved for use in Chemistry 102. DO NOT BEGIN UNTIL TOLD TO DO SO BY THE INVIGILATOR Chemistry 102, Mid-Term Test 2 Version B March 14, 2014 Page 2 of 9 This test consists entirely of multiple choice questions and is worth 50 marks. There are two marks per question. The answers for the 25 questions must be coded on the optical sense form (bubble sheet) using a SOFT PENCIL. The scanner does not read ink of any colour. Select the BEST response for each question below. 1. How much heat is required to convert a 15.5 g ice cube at 5.00C to liquid water at 0C? (The specific heat of ice is 2.09 J/g·K, the specific heat of water is 4.18 J/g·K, and Hfus for water = 334 J/g) A. 5.18 kJ B. 5.34 kJ D. 4.86 kJ E. 5.41 kJ C. 5.66 kJ 2. Imagine a reaction that results in a change in both volume and temperature, as illustrated. Which of the following statements describing the system is/are CORRECT? (i) work was done by the system and its sign is negative (i.e. w is negative) (ii) work was done by the system and its sign is positive (i.e. w is positive) (iii) the reaction was exothermic (iv) the reaction was endothermic (v) the change in internal energy was positive (vi) the change in internal energy was negative A. i, iii, v B. ii, iii, vi C. i, iii, vi D. i, iv, vi E. ii, iv, v 3. For an explosion in a vessel open to the atmosphere, which of the following is most likely to be TRUE? A. ΔH is positive and ΔE is more negative than ΔH. B. ΔH is positive and ΔE is more positive than ΔH. C. ΔH is negative and ΔE is more negative than ΔH. D. ΔH is negative and ΔE is more positive than ΔH. E. ΔH is positive and ΔE is equal to ΔH. Chemistry 102, Mid-Term Test 2 Version B March 14, 2014 Page 3 of 9 Use the diagram above to answer questions 4 and 5. 4. The enthalpy of formation of 1 mole of nitric oxide (NO) is: A. -180 kJ 5. C. +180 kJ D. -90 kJ E. +112 kJ D. -112 E. +34 kJ The enthalpy of formation of 1 mole of NO2 is: A. +68 kJ 6. B. +90 kJ B. -34 kJ C. -68 kJ The average fuel value of sugars is 17 kJ/g. A 2.0 L pitcher of sweetened Kool-Aid contains 400 g of sugar. What is the fuel value (in kJ) of a 200 mL serving of Kool-Aid? (Assume that the sugar is the only fuel source.) A. 68 B. 340 C. 6800 D. 680 E. 3400 7. Using enthalpies of formation from the Data Sheet, the molar enthalpy of vaporization of CH3OH at 25°C is calculated to be (in kJ mol-1): A. +201.2 B. +37.4 C. +18.7 D. -37.4 E. -201.2 Chemistry 102, Mid-Term Test 2 Version B March 14, 2014 Page 4 of 9 8. Aluminum metal (Al) burns in air to produce solid aluminum oxide Al2O3(s). The enthalpy of combustion of aluminum metal is calculated to be? (See Data Sheet.) A. +1669.8 kJ/mol B. -1669.8 kJ/mol C. -1576.5 kJ/mol D. +834.9 kJ/mol E. -834.9 kJ/mol 9. When liquid mercury (Hg) spills on a glass floor, it forms small Hg spherical droplets because: A. The adhesive forces between Hg and glass are stronger than the Hg cohesive forces. B. The adhesive forces between Hg and glass are weaker than the Hg cohesive forces. C. The surface tension between Hg and glass is weaker than the adhesive forces. D. The glass cohesive forces are weaker than the adhesive forces between Hg and glass. E. The adhesive forces between Hg and glass are much stronger than the surface tension of the glass. The figure below is a phase diagram for iodine (I2). Use it to answer questions 10 and 11. 10. When a sample of iodine at position Y in the phase diagram is cooled at constant pressure from 650 K to room temperature, the first phase transition it undergoes is: A. Liquid to gas B. Solid to liquid C. Gas to solid D. Gas to liquid E. Liquid to solid 11. Considering the above phase diagram for iodine (I2), the normal melting point of iodine is? A. 761 K B. 340 K C. 457 K D. 521 K E. 387 K Chemistry 102, Mid-Term Test 2 Version B March 14, 2014 Page 5 of 9 12. Sucre is the constitutional capital of Bolivia and is at an altitude of 2800m above sea level. Atmospheric pressure at this altitude is 0.710 atm. Using the vapour pressure data in the following table, estimate the boiling point of water in the city of Sucre. A. 100 ºC B. 91 ºC C. 93 ºC D. 89 ºC E. 95 ºC 13. When a liquid is in dynamic equilibrium with its vapor in a closed container at a given fixed temperature, indicate ALL of the following conditions that ARE TRUE: i) There is no transfer of molecules between liquid and vapor ii) The vapor pressure has a unique value iii) The opposing processes, (liquid to vapor) and (vapor to liquid), proceed at equal rates iv) The concentration of vapor will change as time elapses. A. i only B. ii and iii D. iii and iv E. iii C. i and ii 14. What is the correct expression for the equilibrium constant of the following reaction? 6CO2(g) + 6H2O(g) C6H12O6(s) + 6O2(g) A. D. [ ] [ [ ] [ [ [ ] ] [ ] ] ] B. E. [ [ ] ] [ [ ] C. [ [ ] ] ] [ ] 15. Consider the following hypothetical gas-phase reaction: A (g) B (g) KP = 3.40 at 25 ºC If a flask initially contains 1.00 atm of each gas, in what direction will the reaction shift in order to reach equilibrium? A. It will shift to the left. B. It will shift to the right. C. The reaction is already at equilibrium. D. The reaction is at equilibrium initially and then will shift to the right. E. The reaction is initially at equilibrium and then will shift to the left. Chemistry 102, Mid-Term Test 2 Version B March 14, 2014 Page 6 of 9 16. Which of the following statements is false? A. The absolute value of the heat of sublimation is equal to the absolute value of the heat of deposition. B. The heat of sublimation is equal to the sum of the heat of vaporization and the heat of melting. C. The heat of sublimation is equal to the sum of the heat of vaporization and the heat of freezing. D. The absolute value of the heat of sublimation is equal to the absolute value of the sum of the heat of condensation and the heat of freezing. E. The absolute value of the heat of deposition is equal to sum of the absolute value of the heat of vaporization and the absolute value of the heat of freezing. 17. An equilibrium mixture of CO, O2, and CO2 at a certain temperature contains [CO2] = 0.0010M and [O2] = 0.0015M. At this temperature the equilibrium constant Kc = 1.4 ×102. 2CO (g) + O2 (g) 2CO2 (g) + heat What is the equilibrium concentration of CO? A. 4.8 × 10–6 M B. 6.9 × 10–2 M D. 2.2 × 10–3 M E. 0.22 M C. 4.6 × 10–4 M 18. Consider the following reaction of mercury and oxygen: 2 Hg (l) + O2 (g) 2 HgO (s) For this reaction, the equilibrium amounts of reactants and products are: 1.00 g of HgO (s), 2.00 mL of Hg(l), and 1.60 mol L–1 of O2(g). What is the value of the equilibrium constant, KC? (In case you wish to know, HgO(s) has molar mass 217 g mol–1 and density 1.10 g mL–1, and metallic mercury Hg(l) has atomic mass 201 g mol–1 and density 13.6 g mL–1.) A. 6.85 × 10–4 D. 1.46 × 10 B. 4.66 × 10–2 3 C. 0.625 E. 1.60 19. The equilibrium constant for reaction #1 below is K. The equilibrium constant for reaction #2 is therefore __________. (1) 2SO3 (g) 2SO2 (g) + O2 (g) (2) SO2 (g) + (1/2) O2 (g) A) K2 B) 1/K½ SO3 (g) C) 1/2K D) 2K E) -K2 Chemistry 102, Mid-Term Test 2 Version B March 14, 2014 Page 7 of 9 20. Consider the following reaction: N2O4(g)  2NO2(g) A flask is charged with 6.000 atm of N2O4(g) and 4.000 atm of NO2(g) at 25 oC. After equilibrium is reached the partial pressure of NO2 is 1.536 atm. Calculate Kp for the reaction. A. 0.326 B. 0.212 C. 0.278 D. 0.215 E. 0.181 21. Given the reactions below, compute ΔH° (in kJ) for the reaction below. (Rhombic sulfur is the most stable form of sulfur.) H2(g) + S(rhombic) → H2S(g) Reaction H2S(g) + 3/2 O2(g) S(rhombic) + O2(g) H2(g) + ½ O2(g) A. +562.3 → H2O(l) + SO2(g) → SO2(g) → H2O(l) B. -1026.2 C. +1026.2 ΔH°rxn (kJ) - 562.3 - 297.0 - 166.9 D. +98.4 E. -69.1 Chemistry 102, Mid-Term Test 2 Version B March 14, 2014 Page 8 of 9 22. Cyclohexane (C6H12) undergoes an isomerization in the presence of the appropriate catalyst to form a compound called MCP. C6H12 (g) MCP (g) Kc = 0.143 at 25 ºC The initial concentrations are [C6H12] = 0.800M and [MCP] = 0.100M. What are the equilibrium concentrations of these two compounds? A. [C6H12] = 0.013 M and [MCP] = 0.113 M B. [C6H12] = 0.113 M and [MCP] = 0.787 M C. [C6H12] = 0.262 M and [MCP] = 0.0375 M D. [C6H12] = 0.787 M and [MCP] = 0.113 M E. [C6H12] = 0..450 M and [MCP] = 0.450 M 23. According to the following chemical equation, the enthalpy of combustion of methane is (kJ mole-1)? (You need data from the Data Sheet.) CH4(g) + 2O2(g) A. -560.5 B. -802.3 CO2(g) + 2H2O(g) C. +890.3 D. +802.3 E. -890.3 Chemistry 102, Mid-Term Test 2 Version B March 14, 2014 Page 9 of 9 24. For the following pairs of substances, which one has the member with the smaller standard entropy listed first? A. ( 100g Na2SO4(aq) at 30 ºC) , ( 100g Na2SO4(s) at 30 ºC) B. (1 mol of H2O(g) at 100 ºC and 1 atm) , (1 mol of H2O(l) at 100 ºC and 1 atm) C. (0.5 mol of CH4(g) at 298 K, 20.0 L volume) , (0.5 mol of N2(g) at 298 K, 20.0 L volume) D. (1 mol of P4(g) at 300 ºC and 0.01 atm) , (1 mol of As4(g) at 300 ºC and 0.01 atm) E. (0.5 mol of CH2F2(g) at 298 K, 20.0 L volume) , (0.5 mol of N2(g) at 298 K, 20.0 L volume) 25. Consider the following spontaneous processes at 298 K: i. H2O(s) H2O(l) ii. H2(g) + O2(g) H2O(l) iii. Ag+(aq) + Cl- (aq) AgCl (s) We can then concluded that the entropy of the Universe increased in A. All three of them B. none of them D. i only E. ii and iii C. i and iii ++++++++++++++++++++++++++++ THE END +++++++++++++++++++++++++++++++++