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Unformatted text preview: Clemson University CH 102 Spring 2012 Mock Exam 1
1. What phase(s) exists at point A in the phase diagram below? 3. Which of the following solids has a very high melting point and as a liquid is non-conducting? A. B. C. D. 4. Na2SO4 H2SO4 SiO2 Na A Use the solubility curve for sodium nitrite, NaNO2, to answer the following question. A solution is prepared by dissolving 60 kg of sodium nitrite in 50 kg of water at 80 C and the resulting solution is cooled to 30 C. Which of the following is true? A. Solid B. Liquid C. Gas 2. D. Solid & Liquid E. Liquid & Gas The phase diagram for CO2 is shown below. Assume point A occurs at 5.1 atm and -56.7 oC and point B occurs at 72.9 atm and 31 oC. What phase transitions occur as you uniformly increase the pressure on gaseous CO2 from 1.0 atm to 10000 atm at 50 oC? ( Assume 1 bar = 1 atm.) A. The cooled solution is unsaturated. B. 90 kg of sodium nitrate is contained in the cooled solution. C. 60 kg of sodium nitrate is contained in the cooled solution. D. 45 kg of sodium nitrate is contained in the cooled solution. E. The amount of solute in solution cannot be determined. 5. Which one of the following substances crystallizes as a molecular solid? A. KI B. SiO2 C. Sn 6. A. B. C. D. gas to supercritical fluid to solid gas to liquid to solid gas to solid it remains in the gas phase D. CH3OH E. Al2(SO4)3 What is the freezing point of a solution prepared from 50.0 g ethylene glycol (C2H6O2) and 85.0 g H2O? Page 1 of 5 7. How much heat must be removed to completely convert 27.0 g of steam at 100 C to ice at 0 C? For water: H2O(s): Cs = 2.09 J/(g C) H2O(l): Cs = 4.18 J/(g C) H2O(g): Cs = 2.01 J/(g C) Hfus = 6.02 kJ/mol Hvap = 40.67 kJ/mol 14. Which of the following correctly matches the type of crystalline solid and the forces binding its particles with an example. Type of Solid A. B. metallic covalent network ionic covalent network molecular Forces hydrogen bonding covalent bonding ionic bonding ionic bonding covalent bonding Example platinum, Pt dry ice, CO2 sodium chloride, NaCl quartz, SiO2 water, H2O 8. Which of the following increases the solubility of a gas in a given solvent? A. B. C. D. E. 9. increasing the partial pressure of the gas increasing the temperature of the solvent both A and B decreasing the temperature of the solvent both A and D C. D. E. Which of the following statements about water, H2O, is true? A. Water has an unusually low boiling point for its molecular weight B. Water dissolves only ionic and polar solutes. C. Water's high specific heat capacity enables it to moderate global temperature fluctuations. D. Water's unique properties arise from its linear molecular structure. 15. The diagram below represents the cooling curve for a substance. For this substance, Hvap is approximately ______ that of Hfus. T 10. Which of the following aqueous solutions would have the largest freezing point depression? A. B. C. D. 0.200 m C12H22O11 0.100 m NH4NO3 0.150 m K2SO4 0.150 m NaCl A. B. C. D. E. q removed half the same as twice four times Cannot be determined from the given information. 11. What is the molar mass of an aromatic hydrocarbon if 0.85 g of it depresses the freezing point of 100.0 g of benzene by 0.47 C? 16. Which phases are stable below the triple point pressure on the phase diagram for water? A. solid and gas D. liquid and gas B. solid and liquid E. solid only C. gas and supercritical fluid 17. A solution exerts an osmotic pressure of 13.8 atm at 35 C. The solute has a van't Hoff factor of 1.85. What is the concentration of the solution? 12. A solution is prepared by dissolving 101.0 g C12H22O11 in 500.0 g of water at 100 C. What is the vapor pressure of the solution if the vapor pressure of water at 100 C is 760 mm Hg? 13. Which pair of properties would you expect for a covalent network solid? A. B. C. D. E. hard with a low melting point brittle with a high melting point soft with a low melting point hard with a high melting point brittle with a variable melting point 18. Commercial concentrated aqueous ammonia is 28% NH 3 by mass and has a density of 0.90 g/mL. What is the molarity of the solution? Page 2 of 5 19. Assuming the following substances all cost the same per mole, which one would be most cost effective as a way to lower the freezing point of water? (Assume complete dissociation) A. B. C. D. HOCH2CH2OH NaCl MgCl2 KCl 23. Nitrogen has a normal boiling point of 77.3 K and a melting point (at 760 mm Hg) of 63.1 K. It has a triple point at 63.1 K and 94 mm Hg. Its critical temperature is 126.2 K and its critical pressure is 2550 mm Hg. What phase is most stable at 140 K and 500 mm Hg? A. solid B. liquid C. supercritical fluid D. gas 20. Which of the following should most favor the solubility of an ionic solid in water? A. a small lattice energy for the solid and a small hydration energy for its ions B. a small lattice energy for the solid and a large hydration energy for its ions C. a large lattice energy for the solid and a small hydration energy for its ions D. a large lattice energy for the solid and a large hydration energy for its ions 21. A beaker of pure water and a beaker of an aqueous glucose solution, C6H12O6, are placed in a sealed chamber as shown below. What will happen to the levels of the two solutions over time? 24. Which of the following best explains why the solid-liquid equilibrium line in the phase diagram for water has a negative slope? A. Water is more dense as solid than as a liquid. B. Water converts to an ionic compound when frozen. C. Water has a more open structure as a solid than as a liquid. D. Water can only solidify under great pressure. 25. Consider the formation of the three solutions shown in the table. Rank the formation of the solutions from most endothermic to most exothermic. Type of interaction solute-solute solvent-solvent solute-solvent A. B. C. D. E. exothermicity I < II < III II < I < III III < I < II III < II < I I < III < II Strength of Interaction Soln. I Soln. II Soln. III strong weak strong strong weak weak weak strong strong A. The levels of both liquids will decrease. B. The levels of both liquids will increase. C. The levels of the two liquids will remain the same. D. The level of the solution will decrease, while the level of the pure water will increase. E. The level of the pure water will decrease, while the level of the solution will increase. 22. A cucumber is placed in a concentrated brine (sodium chloride) solution. What will most likely happen? A. Water will flow from the cucumber to the solution. B. Water will flow from the solution to the cucumber. C. Salt will flow into the cucumber. D. Salt will precipitate out. E. No change will occur. 26. Which of the following would be expected to have the lowest standard molar entropy, So A. B. C. D. C8H18(l) C12H26(s) C8H18(s) C12H26(l) 27. The normal freezing point of sulfur dioxide is 72 C. For the process, SO2(l) SO2(s) at 80 C, the signs of Suniverse, Ssystem and Ssurroundings would be: A. B. C. D. E. Suniverse Ssystem + + + + + + Ssurroudings + + + Page 3 of 5 28. The normal freezing point of sulfur dioxide is 72 C. For the process, SO2(l) SO2(s) at 80 C, the signs of H and S would be: A. B. C. D. H + + S + + 29. For which of the following processes would So be expected to be most positive? A. O2(g) + 2H2(g) 2H2O(g) B. H2O(l) H2O(s) C. NH3(g) + HCl(g) NH4Cl(s) D. 2NH4NO3(s) 2N2(g) + O2(g) + 4H2O(g) E. N2O4(g) 2NO2(g) 30. Using the values below, calculate Srxn for the reaction: Hg2+(aq) + 2Cl(aq) HgCl2(s) Hg2+(aq) Cl(aq) HgCl2(s) S (J/Kmol) 32.2 56.5 146 31. Which of the following arrangements of gas particles would have the largest entropy? A. B. C. D. Page 4 of 5 USEFUL INFORMATION Tb = i Kb m Tf = i Kf m Psoln = Xsolvent Psolvent For water: Kb = 0.51 C/m For water: Kf = 1.86 C/m =iMRT For benzene: Kf = 5.12 0C/m S = kH P So = So (products) So (reactants) 760 torr = 1 atm R = 0.08206 L atm/mol K Page 5 of 5 ...
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