NAME ______________________________________________ © Keeney-Kennicutt, 2010 B1 CHEMISTRY 102 FALL 2010 EXAM 1 FORM B SECTION 501 DR. KEENEY-KENNICUTT Directions: (1) Put your name on PART 1 and your name and signature on PART 2 of the exam where indicated. (2) Sign the Aggie Code on PART 2 of this exam. (3) Each multiple choice question is actually 2 questions on your scanning sheet. If you are sure of an answer, put the same answer down for both questions for 5 pts. If you cannot decide between two answers, put your best answer down for the first (odd) question and the other answer down for the second (even) question. If you get the first one correct you'll get 3 pts; if you get the second one correct you’ll get 2 pts. If there is an ambiguous multiple choice question, use the last page to explain your answer. (4) Do NOT write on the envelope. (5) When finished, put everything in the envelope and wait to be excused. At the table, take everything out of the envelope. You can pick up the multiple choice part with the answers outside my office after 3pm. (6) There are a total of 35 questions (19 actual questions). PART 1 1&2. Which of the following gives an element in its thermodynamic standard state? (a) Sr(s) (b) Hg(s) (c) CO2(g) (d) C(s, diamond) (e) N2(s) 3&4. Which observation(s) reflect(s) colligative properties? (1) A 0.50 m copper(II) sulfate solution has a lower freezing point than a 0.50 m glucose solution. (2) Pure water freezes at a higher temperature than does pure ethanol. (3) A 0.5 m copper(II) sulfate solution is blue, while a 0.50 m glucose solution is colorless. (a) only 2 (b) only 1 (c) 2,3 (d) 1&3 (e) only 3 5&6. In preparing a solution labeled in molality using a solvent for which the density is unknown, it would NOT be appropriate to measure: (1) solvent mass (2) total solution volume (3) solute mass (4) solvent volume (a) 3,4 (b) 2,3 (c) 1,3 (d) 2,4 (e) 1,2 7&8. Which choice includes ALL the following processes that are accompanied by an increase in entropy? (1) Br2(s) Æ Br2(l) (2) Mg(OH)2(s) Æ Mg2+(aq) + 2OH-(aq) (3) 2Br(g) Æ Br2(g) (4) N2(g) + 3H2(g) Æ 2NH3(g) (a) 1,2 (b) 1,3 (c) 3,4 (d) 3 (e) 2,4© Keeney-Kennicutt, 2010 B2 9&10. Which of the following statements about a mixture of water and methanol, CH3OH, is/are TRUE ? (1) Methanol, CH3OH, must have very different polarities because they mix. (2) A “boundary” will be formed between the two liquids. (3) Both molecules exhibit hydrogen bonding. (a) 1&3 only (b) 2 &3 only (c) 1&2&3 (d) 3 only (e) 1&2 only 11&12. From the table of thermodynamic data, we see that ΔHo f 298 (kJ/mol) for NO2(g) is +33.1 kJ/mol. This value is the ΔH for the following reaction: (a) N2(g) + 2O2(g) Æ 2NO2(g) (b) 2NO2(g) Æ N2(g) + 2O2(g) (c) 2N(g) + O2(g) Æ NO2(g) (d) NO2(g) Æ ½ N2(g) + O2(g) (e) ½ N2(g) + O2(g) Æ NO2(g) 13&14. What are the ideal van't Hoff factors for the following compounds: Li3PO4, NaOH, C12H22O11, Ca(NO3)2 ? (a) 1, 1, 1, 1 (b) 4, 2, 1, 3 (c) 3, 1, 4, 2 (d) 7, 2, 1, 9 (e) none of the above 15&16. Which is a FALSE statement about this graph? (a) The rate of evaporation increases with increasing temperature. (b) It can represent how vapor pressure changes with temperature for a pure solvent and a solution. (c) The normal boiling point of the solvent is at the intersection between curve C and 760 torr. (d) The boiling point of a solution is higher than the boiling point of the pure solvent. (e) The boiling point of the solution is about 30oC.© Keeney-Kennicutt, 2010 B3 17&18. Which statement is TRUE? (a) The ionization of a strong acid is product-favored. (b) The sign of ∆H determines whether or not a reaction is spontaneous. (c) A synonym for entropy is order. (d) The entropy of any substance is 0 at absolute 0 Kelvin. (e) For a spontaneous reaction, the entropy of the system must increase. 19&20. Osmotic pressure is important in maintaining a proper solute concentration across a semipermeable membrane in biological systems. The following statements pertain to osmotic pressure. Which of the following statements is TRUE? (a) The concentration of solution particles has no effect on the osmotic pressure of a solution. (b) Only the pure solute will cross a semi-permeable membrane. (c) Solutions of 0.10 M NaCl and 0.10 M NaNO3 would have the same osmotic pressure. (d) Osmotic pressure is the pressure required to prevent the passage of a solute across a semi-permeable membrane because of concentration differences. (e) A higher concentration of solute particles creates a lower osmotic pressure. 21&22. Consider the following reaction: A Æ C with ΔHrxn = –200 kJ and ΔSrxn = +60 J/K. We know: (a) the reaction is exothermic and becoming more disordered (b) the reaction is exothermic and becoming less disordered (c) the reaction is endothermic and becoming more disordered (d) the reaction is endothermic and becoming less disordered (e) it is impossible to know 23&24. When preparing a 0.350 m solution of Na2CO3, what mass of water (in grams) must be added to 10.0 g of Na2CO3 ? (a) 0.171 g (b) 270 g (c) 35 g (d) 230 g (e) 114 g© Keeney-Kennicutt, 2010 B4 25&26. What is the boiling point of an aqueous solution prepared by dissolving 55.0 g of C12H22O11, a non-electrolyte, in enough water to make 260.0 g of solution? (a) 100.11oC (b) 0.40oC (c) 100.95oC (d) 100.40oC (e) 0.85oC 27&28. Calculate the molarity of an 11.0% CuSO4 solution. The resulting solution has a density of 1.12 g/mL. (a) 0.772 M (b) 0.693 M (c) 0.840 M (d) 0.625 M (e) 0.711 M© Keeney-Kennicutt, 2010 B5 29&30. An aqueous solution containing 8.5 g of a polymer (nonelectrolyte) in 220. mL of a benzene solution has an osmotic pressure of 14 torr at 30.oC. What is the apparent formula weight of the polymer? (a) 7,000 g/mol (b) 37,000 g/mol (c) 14,000 g/mol (d) 1,000 g/mol (e) 52,000 g/mol 31&32. Consider this process: H2O(l) Æ H2O(g) ∆Hprocess = +44.0 kJ and ∆Sprocess.= +119 J/K What is the ∆Suniverse at 25oC and is the reaction spontaneous at 25oC? (a) –22 kJ/K, yes (b) +62 J/K, no (c) –29 J/K, no (d) +75 J/K, yes