Exam_1_Fall_2009 - CHEM. 31 EXAM 1 FALL 2009 NAME: This...

Info iconThis preview shows pages 1–11. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 6
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 8
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 10
Background image of page 11
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: CHEM. 31 EXAM 1 FALL 2009 NAME: This exam must be completed without the aid of books, notes or colleagues. You may use a non- programmable calculator; if your calculator is programmable, you must present it to a TA and have it cleared before you begin the exam. All answers must be clearly written in the space indicated and mathematical work must be shown for full credit to be awarded for numerical answers and for all answers for which calculations are carried out. Please write your name on the top of each page. A periodic chart is included as the last page of the exam. GRADING: (Page): Total points . ossible Total points awarded Good luck, and remember: “Nothing shocks me. I’m a scientist.” -- Indiana Jones NAB/IE: Circle the correct answer or write the answer in the space provided. If numerical work is required, show it in the space provided. Points are shown for each problem. 1. (4 points) Which of the following ranks the compounds from lowest to highest in terms of melting point? (a) NaF < Can < Mng < CH3CH2CH2CH2F < CH3CH2CH2CH20H < CH3CH(CH3)CH2F (b) CH3CH(CH3)CH2F < CH3CH2CH2CH2F < CH3CH2CH2CHZOH < NaF < Mng < Can (c) CHgCHgCHZCHzF < CH3CH(CH3)CH2F < CH3CH2CH2CH20H < NaF < Car:2 < Mng (d) CH3CH20H2CHZOH < CH3CH(CH3)CH2F < CH3CH2CH2CH2F < NaF < (:an < Mgr2 (6) none of these shows the correct order. 2. (2 points) Which of the following ions is likely to have the largest ion—dipole interaction with water? (a) Rb+ (b) Na+ (c) Pb2+ I (d) Be2+ 3. (2 points) Which of the following is the best solvent for making a solution of CCl4? (a) H20 (b) CH3OH (c) NH3 (d) C5H5 (e) a and b 4. (2 points) Which of the following processes requires the largest net energy input? (3) (302(5) '9 (302(1) (b) C020) '9 C02(g) (C) (302(5) '9 C02(g) (d) C02(g) '9 (302(3) NAME: 5. (2 points) At the point labeled 0 on the following phase diagram, What phase(s) are present? E EL .9; a 5 D. Temperature (°C) (a) solid and gas (b) liquid and solid (c) liquid and gas (d) liquid only (6) gas only (i) solid only 6. (2 points) Given the following surface tensions, which substance will rise the highest in a glass capillary? —2 2 (a). ethanol (CH3CHZOH) 223 X 10~2 J/mz (b) benzene (C5H6) 2.85 X 10 J/m (c) chloroform (CHC13) 2.68 X10—2J/m2 (d) octane (ch18) 2.16 >< 10‘2 J/m2 7. (2 points) An intravenous injection caused edema (swelling) in the patient. What must have been the osmolarity (osmotic strength) of the solution that was injected? a. c. hypotonic (lower than physiological) isotonic b. hypertonic (higher than physiological) d. can’t tell - need to know identity of solutes NAlVIE: 8. (4 points) In the process of dialysis, specialized semipermeable membranes allow both small molecules and water to pass through, but not large protein molecules. These membranes are used to separate these small molecules and ions fiom much larger proteins. If a mixture of proteins and small molecules were separated from pure water by a dialysis membrane as shown in the figure, which way would the water and small molecules flow? proteins and small molecules in water (3) Both water and small molecules would leave the solution and enter the pure water. (h) Only the proteins would pass into the pure water. (0) Water would enter the solution while small molecules would pass into the pure water. (Cl) Only small molecules would leave the solution and enter the water; water would not flow in either direction. 9. (4 points) The normal temperature range of the liquid phase of pure water is 0°C to 100°C. Which of the following solutions will have the largest temperature range for the liquid state? Assume that the solutions all behave ideally. (a) 2 M aqueous glucose solution (b) l M aqueous potassium bromide solution (c) l M aqueous acetic acid solution (d) 1 M aqueous sulfuric acid solution (e) l M aqueous magnesium bromide solution NAME: 10. (4 points) Click and Clack have identical icy driveways. Click buys 10 lb of NaCl and spreads it on his driveway. Clack buys 10 1b of CaClg and spreads it on his. Which driveway will deice more effectively? (Assume that ideal ionic dissociation occurs and that colligative properties are the only consideration here.) (a) Click’s driveway will de—ice better (b) Clack’s driveway will de—ice better. ((2) The two driveways will de—ice identically. 11. (2 points) During a spontaneous chemical reaction, it is found that ASsys < 0. This means (3) A55“ < 0. (b) ASS“rlr > O (and larger than ASsys). (C) ASSUH > 0. (d) ASS“rr < 0 (and smaller than ASsys). 12. (4 points) The following figures show boxes, each containing one marble. Indicate which of the boxes has the highest entropy. (a) (b) I 13. (2 points) A reaction with a low enthalpy of reaction value is not spontaneous at low temperature but becomes spontaneous at high temperature. What are the signs for AH" and AS" respectively? (a) +, _ (b) —. + (c) —, — (d) +, + NANIE: 14. (6 points) At What temperature does the Fe(s) : F e(g) phase transition occur? nH= 415.5 kI/Inol; AS: 153.4 J/mol - K. (a) 1169°C (b) 2709°C (c) 1321°C (d) 2436°C Calculations: 15. (6 points) The figure shows plots of AH and T AS as a function of temperature. Over What temperature range is the reaction spontaneous? TAS I, 0.0, 20.0, 40.0 60.0 80.0 100.0 Temperature (°C) (a) 0 — 60°C (b) 60 — 100°C (0) 0 — 100°C (d) can’t tell without knowing stoichiometry of the reaction NAB/12E: 16. (2 points) The following graph shows the kinetics curves for the reaction of nitrogen with hydrogen to form ammonia: N2(g) + 3 H2(g) —> 2 NH3(g). Which curve is hydrogen? 8 E E’ 8 g 0 Time (a) a (b) b ‘(c) c (d) none of these could be hydrogen 17. (8 points) Given the following data, determine (i) the order of the reaction with respect to NO(g), (ii) the rate of the reaction with respect to Clz(g), and (iii) the rate constant for the reaction. 2 NO(g) + Clz(g) —> 2 NOCl(g) [NO] (M) [C12] (M) Rafe (M/S) Experiment 1 0.0300 0.0100 3.4 x 10“ 2 0.0150 0.0100 1 8.5 ><10~5 3 ' ' 0.0150 0.0400 3.4 x 10*4 (i) (a) zero order (b) first order (c) second order (d) third order (ii) (a) zero order (b) first order (0) second order (d) third order Calculations: / NAME: 18. (10 points) One of the reactions taking place in the production of photochemical smog is the dirnerization of N02(g). Determine the value of AG° for the reaction and state whether it is spontaneous or nonspontaneous. 2N02(g) : N204(g) Substance AHD (kJ/mol) S° (J/mol - K) N02(g) 33 .2 240.0 N204(g) 9.2 304.2 Value of AG": Circle one: spontaneous nonspontaneous Calculations: 19. (10 points) Determine the first electron affmity of chlorine from the following data: Li(s) + %C12(g) —> LiCl(s) U = Lattice energy of LiCl = — 861 kJ/mol AHvap ofLi = 159.3 kJ/mol AHIE of Li = 520 kJ/mol AHBE of C12 = 240 kJ/mol AHDm = - 408 kJ/Inol Calculations: NAME: 20. (12 points) Nitrosomonas bacteria convert ammonia into nitrite in the presence of oxygen by the following reaction: 2 NH3(aq) + 3 02(g) 9 2 H+(aq) + 2 N02'(aq) + 2 H200) Write a mathematical expressions that shows the relationships indicated: (i) How are the rates of appearance of H+(aq) and N02'(aq) related to the rate of disappearance of NH3? (ii) How is the rate of appearance of NOflaq) related to the rate of disappearance of 02(g)? (iii) How is the rate of disappearance of NH3(aq) elated to the rate of disappearance of 02(g)? ::::::J Work space: NAME: 21. (10 points) The hydrolysis of 1 mole of the sugar maltose (AGDf = —2246.6 kJ/mol) produces 2 moles of glucose (AG°f= —1274.5 kJ/mol): Maltose + H200) -) 2 Glucose If the value of AG°f for water is —237.2 kJ/mol, (i) What is the standard free energy change of the hydrolysis reaction? (ii) Is the reaction exergonic or endergonic? (i) AGom: (ii) Circle one: exergonic endogernic Calculations: 10 51% HE...“ 3. =5 EEK—gm a J: an ,3 “N E a; i . W; or 98¢ lfllfllfl WV, 0 z 0 m. 29. ‘93 ‘93 .333 #98 ups up; a z a a . n ; u w u . 3 a» . u . m m 3 E 3 a a w m o. A... agfimxmsmxmsaflafias : 9..» mo. .2 .<. n? 5. no no SEN: 9 an a mu m. 3. 3.3 88 5. Eu 8: $8 at as $8 $8 Ba 38 EH #9 5» 3.2 3.3 83 .338335 a.sa,assgm~va 2 new. < Naza no, mam—ENS s mama? _ xu an: 3.3 82 an 3.2 an: an. .8. a: an. :3 :3 a; E: E.» as $39. araamaasasaraa nag—h animwnggxndwcmuo.k.m= at a: a: _E a: :3 .8» =3 :8 a; B: B... was a: I x .. B a 3 ‘8 “a m» >9 . . =8 :3 E. a u .3 E $332. was: 33.2,m 273m 3 :5 E: E» :3, an; ES as” aw.» i as as» 3% 338$.33,338§3§§ : cfiliflflfifl awogvmg .Enfifififlnafizvfiegfimgfia Mm ...
View Full Document

This note was uploaded on 10/03/2011 for the course CHEM 31 taught by Professor Roberts during the Fall '10 term at Lehigh University .

Page1 / 11

Exam_1_Fall_2009 - CHEM. 31 EXAM 1 FALL 2009 NAME: This...

This preview shows document pages 1 - 11. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online