CHEM 6A MIDTERM 2

CHEM 6A MIDTERM 2 - MIDTERM 2, Form B Chemistry 6A, FALL,...

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Unformatted text preview: MIDTERM 2, Form B Chemistry 6A, FALL, 200’? __ .. -—...R University of California, San Dieger. JW l ..__J at: _. ***BEFORE BEGINNING MIDTERM 1, PLEASE READ THE FOLLOWING*** 1. Use a #2 pencil 2. Put your name and ID number on this page. PUT THE SAME INFORMATION ON YOUR SCANTRON AS WELL. A=1 for your UCSD ID number. 3. On your scantron, bubble in the form letter of your exam in the ‘test form’ field. 4. ALL MULTIPLE CHOICE ANSWERS GO ON YOUR SCANTRON 5. When finished turn in your scanlron, crib card and this exam. 6. Along with this midterm you may have pencils, erasers, a non-graphing, non-programmable calculator. the periodic tablei’data sheet and your crib card on your desk. 7. Turn off anything that rings or beeps. 8. The Academic Honesty Policy is in full force. Any person caught cheating on this exam “ill receive a O on this exam and be prosecuted under the Student Conduct Code. KEEP YOUR EXAM COVERED AT ALL TIMES YOU MAY WRITE ON THIS EXAM BUT THE MULTIPLE CHOICE ANSWERS MUS T BE ON THE SCANTRON. THE SCANTRON WILL NOT BE RETURNED BUT YOU MA Y COME AND RE VIEWIT BYAPPOINTMENT. + 'l“ '3 F ' < - - NH Ur H you Midterm 2, form B FA LL 20fllit3hnson M 0 - ’4‘ ‘ ll , :an M H l PJ _ K (2 ts.) The chemical formula for ammonium hydrogen phosphate ts a "r :L “ um {2 Choice. ,J @anhftpdi y? flfii’g‘tntfilp d) Matinee: e) none ofthese 2. (2 pts.) The IUPAC name for CugO is a) copper oxide b '-copper([) oxide écoppcrfll) oxide (1) copperflll) oxide c) none of these ' (3 pts.) Which of the following statements is incorrect? r dent‘s-W - . . . .o i/ ‘a) ontc bonding results from the Mr of electrons from one atom to another. ' ' Dipole moments result from the Amgual distribution of electrons in a molecul c) The electrons in a polar bond are found nearer to the more electronegative element/ d) A molecule with very polar bonds can be nonpolan/rlfix C e)‘ Linear molecules cannot have a net dipole moment 4. (3 pts.) Which of the compounds below has bonds with the least covalent character? a) Agl b) AgCl c) AgF (1) men @gnecn “:(4 pts.) On the basis of their lewis structures, place the following in order of decreasing C-O bond length (if resonance is possible take an average of the bond lengths within the resonance structure). /a’)/C0 > CO; > co2 CO;Z ' /tr)/CO > C02 > co; 0 C03; > CO > C02 d); 013‘ a CO: > C0 _ B 23CO3_>‘CO H” C a-hOH f (4 ' h r 11 ' , ‘ ' d' 9 - pts.) Whlc o the fo owmg, specnes IS a ra Ical. F _ __._ H _C_N- Cl 0 ~ u s ‘- a) (21120 HCN M/HCIO @jlnono2 ,6 C10 14,050 7. (3 pm.) When electrons in a molecule are not found between a pair of atoms but move throughout the molecule, this is called a) ionic bonding. d) a dipole moment. b) covalent bonding. fl: delocalization of the electrons. c) polar covalent bonding. 8. (3 pts.) Which of the following has the highest lattice energy? _ f jig/Nam /t{)1<1 @Mgo d) [3210 c) CaO /. f i (5 Pts.) Which of the following structures is lower in energy? .2; a". a) H—E=l\l (ELLE—(ZEN: Midterm 2, Form B~FALL 2007-.Iohnson Consider the following molecules for questions it I 0-] I. [. Bc1~ m—e-CI- . 5‘5“ 1:1- -- _ J , i ' ' P.- f p r F 11. CHBr3 (C IS the central atom) 'C '- .- r I m. Ch I . - — ~ . = I” W" " [—1 ~.F p3. Er fl XE ' Bl /’ ' '— IV. XcBrg C I -- W.) v' CO L r: 1 6 V1. PF3 ~ b Select the molecule(s) that fit the given statement. 10. (5 pts.) These molecules do not follow the octet rule. a) . L W _t!l b) I, III, IV. V] 1" v 1 C) III, V, V] d) I, IV, VI e) I, I], IV. V] (I (5 pts.) These molecules have a zero net dipole moment (nonpolar). a) [11. V b), [11, IV, V ,-c)_ - 1,111.1v ,d) I, III. IV, V! e) none of them 12. (3 pts.) Which of the following has the highest melting point? % RbF (b) KI c) KF d) KBr e} KC] t r 13. (4 pts.) What is the molecular geometry oflCllE’ f. f ‘" _ _l l“— r " 1 /afi/ T—shaped d __ tetrahedral r - A M; E'; trigonal bipyramidai e)/- square planar e) seesaw l4. (3 pts.) For the ground-state ion Bin, what type ol‘orbital do the electrons with highest energy reside in? :1 5d {3, 65 {x6} tag?" 34”“ e 4f d) 5p :3) 6p ta.) Midterm 2, Form B-FALL 2007-Johnson Use the following structure of adenine to answer questions #15-19 H H x /‘~ :TIVIfl’g yN-*C/ KN (My urn Hares. —u i t " ~ ~ we?“ '-l|‘i_"(J\g../L\<‘H 11on I L10 ; N- H I “hi: —— N*: adenine / 4‘ 1 l l 15. (4 pts.) How many nitrogens are 3' hybridized? a)5 b)3 @2 d)! e)0 _H 16. (4 pts.) Describe the orbitals used to form the sigcfig‘ac‘bond between the C* and N*. 519'7- _ .5113; a) 2p — 2p b) sp2 ~ sp" c) 5p3 — sp" Gil/hp2 v sp2 e) sp2 a sp (/1 T. (4 pts.) Describe the orbitals used to form thed’liifiiidnd between the C“ and N*. i a)'~2p—2p b) 519—593 c) 5133*5133 @J'spz—sz 6) spz—sp 18. (4 pts.) What is the *C=*N—C bond angle? C 5 .—— Q 180° 13) equal to 180° C) 4 109° d) equal to 120° e) < 120° 19. (4 pts.) How many sigma and how many pi bonds are present in adenine? a) 14 sigma and 4 pi gin 6 sigma and 4 pi .*-_d b) 185igmaand0pi e) lZsigmaandeifl ;_ _- — — c) 11 sigma and 4 pi r# p (310cc. M - - 113,, « ,L ,, \ 4" [I 20. (5 pts.) The bond order ofer/Is M: g _ 2 :5; 1L. “if _L/ 2 ) L a) 2.5 :92 d) 1.5 e)3 r; . . ' I (th— 1' i "r a [.1— 4 .4, {ark 3-.“ fl... 2]. (5 pts.) Which ofthe following is paramagnetic? '— "" 311619], N at, 11/ .. 1L y/Nz We” (9%} fifo @i-NOi "Ila! 1.311? 22. (3 pts.) All the following elements exist as diatomic gases at room temperature and atmospheric pressure except . I F O t a B {V 353. F N /" Midterm 2, Form B-FALL 200?-Johnson i 2 . ‘ (3 pts.) Which ofthe following statements relating to molecular orbital (MO) theory is incorrect? 24. 26. 5/9"- (3 pts.) An unknown substance dissolves readily in wfler but not in benzene (a a) I Combination of two atomic orbitals produces one bonding and one antibonding M0./ b) I In a stable molecule having an even number of electrons, all electrons must be paired/ c) Combination oftwo 2p orbitals may result in either 0 or 11 MW 6!? A species with a bond order of zero will 11 be stable. e A bonding MO is lower in energy than the two atomic orbitals from which it is formed/ (4 pts.) For dinitrogen monoxide, the arrangement of the atoms is N-N-O. In the Lewis structure with a single bond between NN and a triple bond between NO, the formal charges on N, N, and 0, respectively, are 3‘2; : \f—(L+$/2x) mo 1 a) —l,+l,0. 7N: rN 50', Ni 1 5‘ (n+5) ;—2 b) 0,0,0. “ Nl : 5, (pd—£322”)- : ,1 c) 0,+1,—1. [p ‘11 09—]1+1- O : ape-(24'; g (9/. #2,+1,+1. “W p War solvent). Molecules of what type are present in the substancc'_:‘_J _ neither polar nor nonpolar nonpolar /c,)/ either polar or nonpolar d)_ polar ja/not enough information given (3 pts.) Which ofthe following statements is true? is? / CS? gN‘llfleJcEfii The electroncgativity of an atom is defined as electron affinity of the atom. M The electronegativity of an atom depends only on the value of the ionization energy of the atom. Atoms with high ionization energies and high electron affinities have low electronegativities. Atoms with Waizafion energies and low electron affinities have lgw‘clectronegativities. Atoms with low ionization energies and low electron affinities have high electronegativities. 27. (4 pts.) For HBr, the bonding molecular orbital formed is from the linear combination of atomic 28. orbitals and given by the following equation: is = cqu + 63,1113“ where on = em. a) TRUE bLFALSE Cfiqzcg (5 pts.) All the following have an angular shape except _ | ‘ _ [a .. u .. M55 Lao—act: 'Kzfil gr N3_- " ./"\ H ‘i H y CI?2_- l lbw/i; l, ‘63, IS;be ‘ . _ AYUE Z 1' loib-l In“? ~— “ JV N“ “W- ” ~. O. H e We H M261 :‘g'Fg...g'; M252 29. Midterm 2. Form B-FALL 2007-Johnson (5 pts.) Which of the following has bond angles slightly less than l20°'? C? :‘Q; NLQ: zl- _ “if :83: RIB} AME. -' (A? NOE; “ Hflbflb; AXLE fiXgE-L F‘”. (:53- Ei“ I;‘-"\.- F U 29/ ‘3' H 9""? sadis- «4ng AXZEZ k 71' 3 . (3 pts.) When two atoms are brought together along the x-axis, what IS the number ofo bonds that can be formed by overlap ofp-orbilals on each atom? Liv/ILL b ' l ' c) , 2 . _ d)” 3 (5 pts.) Which oi‘the following has the longest bond? I6 I llW'C" F50 1 m 41'"?- 7 /3’)/ N2 _ 2C3) . m r ‘" fl * .— Ne. We w 1 3/2 w M 0 mt W N32 PL" ‘3 L ‘5 7-?) "<5: ,3»: — 11M. 2m: L 322- ‘5“ it 6 ‘— UW (2') L9 451" "1k 1L - . 2 J— r“-\\ x __ m- :a- ( 3’ - Lo ‘43:» 32. (1 pt.) Did you fill in your student ID number on your seantron? ll- 3’1 fl LI/SIL b) no 5yes 33. This is version B. Mark “B” as the answer to this question m in the “TEST FORM” box on your seantron (below ID number): (2 points if‘you do BOTH} VERSION B @ ...
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CHEM 6A MIDTERM 2 - MIDTERM 2, Form B Chemistry 6A, FALL,...

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