mid 1 spring 01 - CHEM 14A Hour Exam 1 m4 swat? (EV Spring...

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Unformatted text preview: CHEM 14A Hour Exam 1 m4 swat? (EV Spring 2001 Friday, April 27 Prof. H. D. Kaesz 11:00- 11:50am T.A.'s: Mike Bedard, Tom Miller Underline your T.A.'s name to facilitate NAME: return of exam. ||IIIIIIII|IIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIII II I LAST . FIRST STUDENT I.D.: I I I I | | I I I I I_L_J_I_I_J__I__I_I_I SIGNATURE IESTBUQIIQNS: 1.Please give SID and sign above. 2.Answer each question in the space provided. I Question I Possible I Actual I IWI 3 .Where reasoning is requested, this should be I I | I well organized and legible. | l l 34 | I I l I I 4.All answers MUST appear on respective pages. I 2 I 34 I l I I | I - I 3 I 32 I I F__-_I——_I_—_—_—I ImJ—LQLg—I Use the following information as needed. c = XV NA = 6.022 x 1023 rnol‘I E=hV h=6.626x10‘3‘ J S A = h/mv 1 eV = 1.6022 x 10"9 J Ekzhv-Eo 1J=lkgm2s'2 me = 9.109 x 10-“ kg c = 3.0 x108 m s" A sheet containing the PERIODIC TABLE and other information will be separately distributed. pagel Name A—Méwefi. KEY 1. (34 points total) a. (14 pts) Provide the missing coefficients to balance the two reactions below. The reaction of sodium metal with water to give sodium hydroxide and hydrogen. 2 Na+ ; H20 = 2Na0H+ I H2 The reaction of sulfuric acid with calcium phosphate to give phosphoric acid and calcium sulfate. 3 H2s04+ / Ca3(PO4)2 = 2 H3PO4+ 3 CaSO4 b. (10 pts) The combustion analysis of a 1.520 g sample of an organic compound known to contain only C, H, and 0 yielded 4.430 g of CO2 and 1.206 g of H20. What is the %C and %H content of the organic compound? Show method. %C = 77153 %H= 8.28 ~ zoo ‘ ‘ Smrflg 77.531 [.104 L0 = 0.850314 2.0/6 14/ [3.0/6 ,pM we :4 ms‘ZH Lucyswl‘l‘ c. (10 pts) The molecular mass of an oxygen-containing organic compound is determined to be approximately 138. The pure compound is found to contain 11.75 % oxygen. Calculate the exact molecular mass, giving your answer with the appropriate number of significant figures. Show method. ,3 G 2 Ans: ' x 0.1171: : /6.2l5,—’_if§:*¢_ .Wéwgl Mt My). 1 nWax—w x: Wfiéf M"m' 129—9—- ’ 0.1/75/ X: / page 2 NMCM 2. (34 points total) a. (6 pts) The binding energy of the outermost electron in strontium is 2.74 eV. Calculate the wavelength of light which matches this energy. Show method Ans. A. = 452 nm 2374;247/i Mon «ro’mié/ .3¢é3{ - Erf‘f }=<(.CZ‘,.IO = 4.52xio 71M. 3 mum—'52“ 4sa-xto'7wu b. (8 pts) Calculate the kinetic energy of an emitted electron when strontium is irradiated with purple light (7» = 420 x 10'9 m) in a vacuum. ’I7 I. 3? x/O I Show method Ans.EK= 0‘ 34x“? J E“ (W - Go Go: 2.74am“ aQJ-uve) - #. 39).;0"5J' .9/ 3 , . ‘ Aw {LE = m m tr (3” ’1 > s 4.79M"? } qloxlo'qfl I Eka.[*-l-.’lS—-4-39>xzo’ if , 0.35/5”: c. (12 pts) Give the electron configuration for each of the following atoms or ions. Ne ISLZSLZE‘ A13+ s 35156; cr [Av] d. (4 pts) Is the atomic radius of Na larger or smaller than that of C1? Give reasoning. The atomic radius of Na is 161123 than that of Cl larger or smaller e. (4 pts) Is the atomic radius of Cl~ larger or smaller than that of Cl? Give reasoning. The atomic radius of Cl' is éfijw than that of C1 larger or smaller é—JJWV‘D page 3 Name 339,; «4 £11 [fie—Z 3. (32 points total) a. (8 pts) Draw a Lewis structure for the anion [BFJ . This anion may be viewed as a Lewis acid/base complex. Indicate the constituent Lewis acid and Lewis base in the places indicated below. Lewis structure constituent constituent for the anion [BE]- ‘_ Lewis acid Lewis base :5: B ' 3% F The Lewis structure for HZCO3 (carbonic acid) is shown ,O-H at the right. This consists of unequal bond lengths of O=C\ C-0 143 pm, and C=O 112 pm. O-H b. (8 pts) Draw the Lewis structure (or structures) for the carbonate ion [CO3]2' and provide an estimate of the carbon-oxygen bond length below. Show work) 95: /0 .110 ’ . Cl 2 (“453 + “2" o: C 4—9 ’ Owe—‘6, "‘> ".9 ’ \‘gx. 3 Approximate carbon-oxygen bond length in the carbonate ion, [CO3]2' ’33 pm. c. (16 pts) Draw the Lewis structure (or structures) for each of the following molecules. Include the charge on all atoms whose formal charge is other than 0. N20 . so2 « NEISHS: ’.'o;s‘\o:'. H //§: ‘ " ‘- " :0 ..‘53 n “ + . A12C16 "EKM/ 9‘ \Aj/ ../ \é / \ l [a " + H ***end of exam*** ...
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This note was uploaded on 02/08/2012 for the course CHEM 14A 142042200 taught by Professor Lavelle during the Spring '10 term at UCLA.

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mid 1 spring 01 - CHEM 14A Hour Exam 1 m4 swat? (EV Spring...

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