FORMA is EXAM I, VERSION 1 (v1) Name

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1 FORMA is EXAM I, VERSION 1 (v1) Name 1. DO NOT TURN THIS PAGE UNTIL DIRECTED TO DO SO. 2. These tests are machine graded; therefore, be sure to use a No. 1 or 2 pencil for marking the answer sheets. 3. Completely blacken the answer circle. If you change an answer, erase completely the previous mark. 4. You may remove you answer sheet from this booklet. If you have a pink test, test form A should be darkened (B for Blue), if it is not, notify your instructor immediately. 5. Fill in your last name, first name, and initial. Blacken the corresponding letters below. 6. Fill in your ID number. CAREFULLY, blacken the corresponding numbers below this section. 7. Fill in the Dept. Course No. and Section. The Dept. = CHEM, the Course No. = 102, and your section refers to your lab section. 8. If you what your scores posted by a portion of your ID #, mark A under the option column. 9. READ THE TEST CAREFULLY. The time limit on this test is 50 minutes. 10. Use the test for scratch paper. 11. Mark your answers in this booklet as well as on the answer sheet so you can check your score with the key after the test. 12. There are 17 questions. Each counts 6 points for a total of 102 points. NO GRADES OVER 100 WILL BE RECORDED. 13. Your score will be calculated from the number of correct answers. There is no penalty for guessing. 14. Turn in your scan sheet, show your ID, and have your calculator checked. You will also turn in your test. 15. A key will be on the electronic class bulletin board at 2:15PM. This is accessed through the class homepage IMPORTANT INFORMATION: S for liquid water is J/g degree C R = L atmos/ K mol or R = J/k mol F = 1.8 C + 32 c = 3.00 x 10 8 m/s J = 1 calorie S liquid water = 4.184J/g C ΔS surr = -ΔH sys /T ΔG sys = -TΔS univ 102 Sample Exam 1-1 page1

2 1. Select the one equation shown below for which the enthalpy change for the reaction is the standard heat of formation for the product. A B. C. D. E. C 2 H 4 (g) + H 2 (g) H 2 (g) + Br 2 (l) O 2 (g) + 2F 2 (g) C 2 H 6 (g) 2HBr(g) 2OF 2 (g) 2. The value of ΔH for the following reaction is -186 kj. How many kj of heat would be evolved from the reaction of 25 g of Cl 2? H 2 (g) + Cl 2 (g) 2HCl(g) A. 65 B. 5.3 x 10 2 C. 131 D. 47 E Which one of the following substances would be the most soluble in H 2 O? A. CCl 4 B. Cl 2 C. Br 2 D. CH 4 E. RbCl 4. For a certain reaction at 250. degrees C, ΔG = kj AND ΔH = kj Calculate the entropy change at this temperature in J/K A B C D E Substance ΔH f o (kj/mol) IF(g) -95 IF5(g) -840 IF7(g) -941 What is the value of ΔH for the following reaction? IF 5 (g) + F 2 (g) IF 7 (g) A kj B kj C. 101 kj D kj E. more data is needed 102 Sample Exam 1-1 page2

3 6. Which one of the following substances would have the largest absolute entropy (S ) at 25 C and 1 atm pressure? A. SO 2 (g) B. H 2 O(s) C. Ne(g) D. He(g) E. CO(g) 7. When solid ammonium chloride dissolves in water, the solution becomes quite cold. Which of the following CORRECTLY describes the thermodynamic changes in the formation of the solution? A. G<0, H<0, S>0 B. G<0, H<0, S<0 C. G>0, H>0, S>0 D. G<0, H>0, S>0 E. G<0, H>0, S<0 8. You need to heat a reaction to C in a sealed steam chamber, but are not sure your research grant can afford it due to the cost of a joule of heat. Calculate the amount of heat (in joules) required to convert 92.5 g of water at 25.0 C to steam at C Sp. Heat of H 2 O(s) = 2.09 J/g * C Sp. Heat of H 2 O(l) = 4.18 J/g * C Sp. Heat of H 2 O(g) = 2.03 J/g * C Heat of fusion of H 2 O = 333 J/g Heat of vap. of H 2 O = 2260 J/g A x 10 5 J B x 10 5 J C x 10 4 J D x 10 5 J E x 10 4 J 9. A reaction has G = +130 kj, H = +178 kj, and S = +161 J/K at standard conditions. Estimate at the best temperature range at which the reaction will become spontaneous. A. T < 1106 C B. T > 1106 C C. T < 833 C D. T > 833 C E. T > 25 C 10. What is the freezing point (in degrees C) of a solution prepared by dissolving 11.3 g of compound Z (molar mass = 164) in 115 g of water (molar mass = 18)? The freezing point depression constant for water is 1.86 C m -1. A B C D E Your hot dog drips on your best shirt, so you take it to the lab and try to clean it. The spot does not come off with CC1 4, so what do you conclude: A. The substance is nonpolar and should come off with water. B. The substance is polar and should come off with water. C. The substance is nonpolar and will not dissolve in water. D. The substance is polar and will not dissolve in water. E. The shirt should be burned; CCl 4 dissolves everything that can be dissolved. 102 Sample Exam 1-1 page3

4 12. If you know these two equations: 3Fe(s) + 2O 2 (g)----> Fe 3 O 4 (s) whose G = kj AND C(graphite) + O 2 (g) --> CO 2 (g) whose G = kj Find the G in kj for the following equation: Fe 3 O 4 (s) + 2C(graphite) --> 3Fe(s) + 2CO 2 (g) A B C D E The normal boiling points of toluene, carbon tetrachloride, and acetone are 100 C, 76 C, and 56 C, respectively. Which of the following is true? A. The vapor pressure of acetone is the highest. B. The vapor pressure of all three are the same when the substances are at room temperature. C. The vapor pressure of toluene is the highest. D. The vapor pressure of carbon tetrachloride is the highest. E. Not enough information is given to decide. 14. Which equation represents a reaction that has a positive value for work? A. B. CaCO 3 (s) CaO(s) + CO 2 (g) 2C(s) + O 2 (g) 2CO(g) C. 2Na(s) + 2H 2 O(l) 2NaHO(aq) + H 2 (g) D. 2H 2 (g) + O 2 (g) 2H 2 O(l) E. all of these have zero or negative values for work. 15. The vapor pressure of pure water at 25 C is 23.8 mmhg. What is the vapor pressure of water above a solution prepared by dissolving 18 g of glucose (a nonelectrolyte, MW = 180) in 95 g of water? A mmhg B mmhg C mmhg D mmhg E mmhg 102 Sample Exam 1-1 page4

5 16. Given the reaction: C(g) + H 2 (g) + F 2 (g) ---> CH 2 F 2 (g) What is the heat of reaction, ΔH, in kj at 25 C? Bond Energies (kj/mol) at 25 C C H 414 C F 486 H H 435 F F 159 H F 569 A kj B kj C kj D kj E. a positive value not given 17. Which liquid will have the LOWEST freezing point? A. pure H 2 O B. aq m CoI 2 C. aq m AlI 3 D. aq m glucose (C 6 H l2 O 6 ) E. aq m NaI Key question 6 pts each (unless noted) 1 A 2 A (C=3pts) 3 E 4 C (E=3pts) 5 D 6 A 7 D 8 D (B,E= 2.5 pts) 9 D (B=4pts, C=2pts) 10 D (E=3pts) 11 B 12 C 13 A 14 D 15 B (A = 3pts) 16 C 17 B 102 Sample Exam 1-1 page5