CHEM 206 PRELIM 1 + KEY 2006

CHEM 206 PRELIM 1 + KEY 2006 - CHEMISTRY 206 First Exam...

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Unformatted text preview: CHEMISTRY 206 First Exam, Sept. 28, 2006 Page 2 0f 9 The first 5 questions all refer to the elements marked by a letter, A-D, in the following periodic table — yes, with the help of the real periodic table in the booklet you know what those elements are... B is not boron and C is not carbon. Here A, B. C, D are just letter symbols for elements in that place in the table. (1) Which element is a gas at room temperature and normal pressure? A B C ( D 2 (gKWhich element most easily forms a cation? (3) What is the correct formula of the bromide of element C? CBr (Cami cam CBg (4) Which element reacts rapidly with water giving off hydrogen? L60? B C D (5) Which of the following reactions, not balanced, is likely to proceed easily? (a)A++B——>A+BZ+ (m#+ cas+fi (c)D-rA-a D++ A Iw)c-tA-a-cz+-A+Wfi ”W. “N.“ «m flu... A", Winn-M That’s the end of the questions referring to the periodic table on p. 2 CHEMISTRY 206 First Exam, Sept. 28, 2006 Page 3 0f 9 (6) Natural vanillin is (31613:) less radioactive than vanillin produced synthetically. (7) Which one of the following ionic compoundsw is unlikely to exist? LiF CaClz KBr < 35%: > SrS (8) In which one of the following sets of three atoms and ions do all the three species have the same number of protons? (a) B‘, Kr, Sr” (b) c, N3", 02' (0) Mg“, Sr“, Ba2+ “L-utw-mmma. (9) What is the identity of element 0 if the ion 02+ contains 36 electrons? Ge Se Kr ( Sr / (10 ' ow many m3? (a) 1.00 x10'4 m3 (b) 1.00 x 10° m3 (c)1.00 x104 m3 (d)1.00 x108 m3 (11) The nitrate ion is N022+ N02" Q9 No+ This is the end of the multiple choice questions. From now on, please be sure to show your work. (12) (1 O) The world record for the 100m (100.00m) dash is 9.77 s. If a runner could maintain that pace for a mile, how long (in minutes) would it take him or her to run a mile? l mic. 2:: lead? 00 léoqm/ 4,745 x. l5=7~.lclqs m age lmtt x looEbfix Mo x 619% 68 mm time to run mile = 2,6 2. minutes (13) (52 ptsg The +3 ion of an element has the electron configuration Kr 5s 4d 5 . . What is the element? [ ] I0 E CHEMISTRY 206 First Exam, Sept. 28, 2006 Page 4 0f 9 (14) (5 points) Write the electron configuration for the Po‘ ion: age-MS ($1 aslzpé 352.3 6 £51361 loqpé 552. M (0523665.; ‘wafi IOéPS 6r BC} 66‘ ‘HQ 5d “9699 (15) (6) There are two tables at the end of this exam booklet, other than the Periodic Table. (a) What quantitative property is being indicated in the first table (top of last page), other than the atom'c number of the element? (07130! My a" mea/rM/Mfla/ (b) What property of an atom is being indicated in the second table (bottom of last page)? dafrmja/wréx (16) (6) Here is a plot of something related to the ground state of the hydrogen atom. Please label both axes. (17) (6) Here is an important plot for any diatomic molecule, E2 (E—E). Please label both axes. (18) (6) (a) Which atom is bigger, Rb or K? flfl it» Why? 097 A76 ,rmx»~mrw w m 55* ,. ”5'3 " u r» r» m M , . ~ Frag I? 2 my atsr‘rz'uw 2 90/0146! MM A” as; CHEMISTRY 206 First Exam, Sept. 28, 2006 Page 5 of 9 (19) (12 points) Here are some electronic transitions for a hydrogen atom. (a) 33 9 4p (b) 2p 9 3d (c) 4p 9 23 (d) 5f 9 3d (A) Which of these would involve emission of light? CC) and £0 (B) Which electronic transition would result in the absorption of a photon of the lowest energ ? Show reasoning, and fill in answer as x 9 y at end. 1% Wp [mm are, 0) v“ @jfiwyafl m any 5""Qlth’3 Agar?” figL/wti)» 0.04% H m Aer” Jaw-é) 2&er vé. ,, 123%,) ,, 5m 2%; :25?! :21 Effififmvgg, lamarfiym transition resulting in absorption of lowest energy photon is 2% cayp (20) (20 pts) The absorption of a photon of wavelength 4.67 x 10% is necessary for a CO molecule to pass from one of its energy levels to the next higher energy level. If the higher level has an energy of 6.41 x 10—20 J, what is the energy of the lower level? Energy %/Mw$0~= has =55 T ~-—- @310 “Evitéfléewfifi 4969 K 0 If x 4.2565 x/o'wf ’20...‘ [owe/Mao 02‘ 6,9/ x/o’w—4.286€x/0 J '20 :2 8- 15x “3,203— Téclil H0 T ‘TMxlt’Jm’G‘QAzuéqxlo'bm 3 - ~20 EC F— 1245340 energy oflowerlevel: 2,16“; [0'40]— CHEMISTRY 206 First Exam, Sept. 28, 2006 Page 6 0f 9 (21) (10) (a) What is the chemical formula of the gas involved in the greenhouse effect, and the major contributor to global warming, whose production California is trying to restrict? C 0 2 (b) Write a Lewis structure for a molecule of that gas, including all valence electrons. C02, 442:6 =~l6 VaQJAm weLch ' O I: C “—10: 4(st Hf unshared pair's Lirz, + 4.1;. ((3 ’ (22) (8) Propanol is an alcohol, CH3CHZCH20H. Draw a Lewis structure for this molecule. Include any lone pairs. (’30 Hg '3. q rté + 8’4 «222 (2 'l 'l ‘l Hemmzrm M I“ ‘wgaw‘ Paws ",rC Cf"? 9. H zuqmaa H H H (23) (8) This is the chemical structure of acetaminophen, Tylenol® \ | ,J :9 N ‘u . O H a “f ' ’ H / acetaminophen It’s got two hydrogens indicated, but is missing a few more. (a) How many hydrogens in total does acetaminophen have, those indicated plus those missing? q (b) How many unshared (lone) electron pairs (two electrons = 1 pair) need to be added to this structure, to make a proper Lewis structure of the molecule? 5" WW (twists CHEMISTRY 206 First Exam, Sept. 28, 2006 Page 7 of 9 (24) (11) (a) Draw two Lewis structures for N(NH)F, atoms connected as indicated, N to NH to F. 261 1+?- =.~ l8 d1c+vfl5 » fimflfl {‘44— 8“ ‘31". [ WW -' ‘ \ . ' / "o ’3’ \ ‘ l O/NEE’ Q.“ + ’59 C) B (b) Indicate which resonance structure would be preferred, by circling A or B + Marga; Fem/r199, was rig/figfwmém Mimi (25) (6) What bond angles do you expect for: (A) The F-O-F angle in OF2 Fmgs /0?($Ci Vefia 6 7: 621% (B) The H-C-C angle in acetylene, C2H2 MW: F/W H—CanH (26) (12 points) The element antimony has an atomic weight of 121.757 amu and only two naturally occurring isotopes. One isotope has an abundance of 57.30% and an isotopic mass of 120.904 amu. What is the mass of the other isotope? 512.30 ‘3; my l20.90q --l— Lie, #029 of: X (0'5“730Xl2w20t) + (dim/ax 19,357. 6a.??? (MW—0x = 52M“! K“:- @230 The mass of the other isotope of antimony is = l? 2 , Ci amu ...
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