Chem31LExam_1Key(F'2011

Chem31LExam_1Key(F'2011 - CHEM 31 L - Multiple choice...

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Unformatted text preview: CHEM 31 L - Multiple choice questions — 1) For a particular process q = -10 k] and w = 25 kJ. Which of the following statements is true? A) Heat flows from the surroundings to the system. B) The system does work on the surroundings. V C) AE = -35 kI D All of these are true. None of these is true. 2) Which of the following lists only state functions? A) work, heat B work, heat, enthalpy, energy @ enthalpy, energy D) work, heat, enthalpy E) heat, enthalpy, energy 3) A 22.4-g piece of aluminum (which has a molar heat capacity of 24.03 J/mol°C) is heated to 84.8°C and dropped into a calorimeter containing water (the specific heat capacity of water is 4.18 J/g°C) initially at 22.8°C. The final temperature of the water is 27.0°C. Calculate the mass of water in the calorimeter. ism“ 37"“ AL-mas’: ' awed-B: n52? C) 7.0 x101g 3‘1 5‘M MV’L D) 2.0 g _ . = E) 0.35 g “52 3 ~ {who MB 33.13sz 22. 2h 4) Consider the following numbered processes: 1. A —> 2B 2.B—>C+D I AAZB NM 3.E—>2D AH for the process A —> 2C + E is A) AH1+AH2+AH3 2") A E .- ‘5“3 B) AH1+AH2 “‘5 C AH1+AH2—AH3 A“? 2‘ “5 m‘nm\143q3 AH1+2AH2—AH3 E) AH1 + 2AH2 + AH; 5) Which of the following statements about quantum theory is incorrect? A) The energy and position of an electron cannot be determined simultaneously. B Lower energy orbitals are filled with electrons before higher energy orbitals. @ When filling orbitals of equal energy, two electrons will occupy the same orbital before filling a new orbital. No two electrons can have the same four quantum numbers. B) All of these are correct. 6) Consider an atom traveling at 1% of the speed of light. The de Broglie wavelength is found to be 3.31 x 10'15 m. Which ' ’- a 4 «to: mergésmm =———“ =) m ‘3)“ = ("($‘Hng 3'5 ._.(..(.8xm i . C V C F21 WW (3.3a ‘Llo'vsn-XSp mo"nlA D) Be ~26 u . E) P (o'hajfio ‘ (wiltw __ 0,040 Kfi O 7) Consider the following orderings. w l. Al<Si<P<Cl ll. Be<Mg<Ca<Sr Ill.l<Br<Cl<F IV. Na+ < Mg2+ < Al3+ < Si4+ Which of these givefs) a correct trend in size? . I 11 only C) III D) IV only E) 11, IV 8) Which of the following is not determined by the principal quantum number, n, of the electron in a hydrogen atom? A) the energy of the electron B) the maximum wavelength of the light needed to remove the electron from the atom. C the size of the corresponding atomic orbital(s) @ the shape of the corresponding atomic orbital(s) All of the above are determined by n. 9 What is the electron configuration of indium(In)? A) 1s22s22p6352'3p63d1°4sz4p64dl°5s25p15d10 B) 1s22s22p63sz3p63d1°4sz4d1°4p1 c 1323822p63sz3p64sz4p64d1053‘5d105p1 1522522p63sz3p63d104sz4p64d1°5525p1 none of these 10) Which of the following combinations of quantum numbers do not represent permissible solutions of the Schrodinger equation for the electron in the hydrogen atom? (In other words, which combination of quantum numbers is not allowed?) (Combinations are listed as follows: 11, I, ma), 771(5).) A) 9 8 —4 1/2 B 8 2 2 1/2 6 —5 —l l/2 D) 6 5 —5 1/2 E) All are allowed. Name FREE-RESPONSE PROBLEMS: (SHOW YOUR WORK TO RECEIVE PARTIAL OR FULL CREDIT) 1] Hydrazine, N2H4, decomposes according to the following reaction: 3 N2H4 (1) ‘3‘ 4 NH3 (g) + N2 [g] Ea) Giver—1 thatthes’eandard—enthalpyef—fermatien efhydrazine is 59.421flfmel, calculate Ari-l0 for its decomposition. ~ Bfi°r$n = i h my, -— Z n NXF Q‘ch}\ bV‘th-z 4tqb‘5xslmm A, O - ($BCS'OHL \CG/h0\\ -: - 33(Ls- wry/me“ (b) Both hydrazine and ammonia burn in oxygen to produce H20 (1) and N2 (g3. Write balanced equations for each of these processes and calculate AHO for each of them. r (A “znq\&\ "' 01 a N2l°\\ "' ZAZOLQN Cm 4 Ms can * 30%;? <9 10ch * to “20m Q\AL\\ =- ‘k& * 94—2898 mlm0\\ _ (80.42 KIT/“‘8 }£\(Dj :: - b22.0 \LSJMR QAL 2: E2403 {-kfl‘las. 8 K's/V‘qu — ¥d/W‘“ *3 : —\sa‘\.fe fl/m (c) On a mass basis would hydrazine or ammonia be the better fuel? (justify your answer by calculating k] / g for both) . _ _ G 5‘ NLPK‘ _ (97.2 K3)w\ ‘1‘ \h\hz,\ q :— _ \O\f,\ (3,05 \m ulna 3?.0S‘3Nzlkk \ a 482%. m \m\ “H3 ,_. _ 39 5 (6/ 6.. 3.2th ‘ i —— ~ - a n w» A mm NR3 ‘ l”\ 8 NW3 / 2) You explored the energetics of hydrogen-like species such as He+ in recitation. (a) Calculate the ionization energy in (kl/mol) of the He+ ion. . ‘2— ' bE :- Ega" El : C“ 9‘8 xviw ‘5\('a\z — (f 2'18 K\0.18:\G\2 1 .- .. o + (248 K\o“83\(z\2 ‘4 8H1 x10 ‘82)— _. 23 _‘3 MT (“022 Mo KT kg 71 'Z K\ O 3\ 755% )L hm = $125 $103137 m\ 1 Mo\ (b) On a planet where the temperature is incredibly hot, most He“ ions have their electron in the n = 4 state . What is the ratio of IE on this planet to that on earth? bk?“ 5.,“ E4 , \8 '~ I 1 - gasmom T mh" +0 “RM : (2 \9 >00 'S\(2-\ 4 " auxst ‘~ 7H9 7. 54 = l—l—A Or‘ / 3) How many microwave photons at a wavelength of 12.7 cm must be absorbed to melt 5.0 x 102 g of ice at 0°C? (b) On average, how many H20 molecules does one of these photons convert from ice to water? [it takes 334 I to melt 1 g of ice at 0°C) (5.0 xlozgitcxfi%3<fi : \-L9"l ‘MOS :3— h; NW €003?“ Emcb o-l ox 'Pholbn “9/ '1 lZfl UM E -— \nc __ (Cacao no“ T-s\(2.€\°\na 1 {OS n/e.\ l V2,"! inc—7’ M fl fi’Pyc’ms Um no“ 3\ x :\1.o"l x it)” pMoluns\ mm, “0‘” I)” / ‘23 . \Q\ (510 K\D-La \\2()\ x \wu\ “no 7‘ (9.02.2 \LKO h0\fwb) : \."'l ‘MOZ( “20 moved“ Lq moz< \X-Lo MOMMKL': Lsfi X“)- \~\ZO n3waL/ Philbn\ ' fr—‘f-T’J f— \. o"! \(\O PMQW$ ...
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This note was uploaded on 12/05/2011 for the course CHEMISTRY 31 taught by Professor Roy during the Fall '09 term at Duke.

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Chem31LExam_1Key(F'2011 - CHEM 31 L - Multiple choice...

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