KMT1s2 - \LQ. Last Name 3 First Name Lab Sec, # _; TA: ;Lab...

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Unformatted text preview: \LQ. Last Name 3 First Name Lab Sec, # _; TA: ;Lab day/time: Rolf Unterleitner Fall 2010 CHEMISTRY 2A Section 2 EXAM 1 Instructions: (Circle One) CLOSED BOOK EXAM! No books, notes, or additional scrap paper are permitted. AH information required is contained on the exam. Place all work in the space provided. If you require additional space, use the back of the exam. A scientific calculator may be u5ed (if it is a programmable calculator, its memory must be cleared before the exam). The exam has 9 pages. (1) Read each question carefully. (2) For Parts I and II, there is no partial credit given and My answers marked on this cover page will be graded. (3) At the end of page 8 there‘is some useful information. Page 9 has a periodic table. (4) If you finish early, RECHECK YOUR ANSWERS! U.C. Davis is an Honor Institution 1 0‘- 1 5 total points: Name (Page 2 of 9) Exam 1 Part I: Multiple Choice, Concepts (4 points each) Select the best answer and enter your choice on the cover sheet - No partial credit 1. All water is found to be 88.8% oxygen by mass and all hydrogen peroxide (H202) is found to be 94.1 ‘70 oxygen by mass. This is an example of the Law: a. of Conservation of Mass b. of Multiple Proportions @ of Definite Proportions d. E: mcz e. none of the above 2. The atomic mass of chlorine is very close to 35.5. Which of the following is INCORRECT: a. Chlorine occurs with a variable number of neutrons. w”— b. If there are only 2 isotopes of Cl, Cl-35 and Cl-37 there is more Cl-35. 'T" c. Cl-35 is M 2.91 time the mass of C427?" 37; Q3 Most chlorine atoms have a mass of 35.5. 71, ” e. All chlorine atoms contain exactl 17 rotonsp . . y p “l gimme: Jill 2K”? "22 3. Groups, or families, on the periodic table are: @ vertical columns of elements with similar properties. b. horizontal rows of elements with increasing atomic numbers. c. named for the first elements in the series; such as "actinides." d. extremely reactive with each other. e. elements which all occur naturally in the same state. 4. Arrange the following in order of increasing oxidation state of sulfur: ,/ 2. +61% «it 2,. £223 2 1222412 WK...» 5 K25,K2503,K2502 and K2504. 0”" ‘2“ W KZ£0¢ a. K25, K2503, K2502, K2504 f- V) ,1; + ((1 («—2.3 v 0 Lb. K25, K2502, K2503, K2504 20”) ’ \K— in!" Q; WK2503, K2504, K25, d. K25, K2504, K2503, K2502 ,3 a.) w: 3' <Lt}<‘<~ 2:54.70 J; I 1 em K2503, K2502, K25 . Name (Pa e 3 of 9) Exam 1 5. Choose the INCORRECT name-formula combination. @Al203 dialuminum trioxide b. HCIO3 chloric acid c. (NH4)2$203 ammonium thiosulfate d. MgHz magnesium hydride %\ e. SiOz silicon dioxide 5 6. Which of the following are isomersgy/ ' W /a./ CH3CH(CH2CH3)CH2CH2CH3 and,CH3CH2CH(CH3)CH2QH2CH3 /b.” CH3CHCHCH2CH3 and CHin(CH3)CH2CH2CH3 W" c. CH3CH(NH2)CH2CH2CH3’and CH3CH2CH2CH(CH3)NH2 \A £~-~»\\__d;_ Ehl3§\H2CH2CH2CH3 and CH3(CH2)3CH3 a ’S’ r” NM + e. CH3)4C and CH3CH2CH2CH26H3 r v /\/\ 7. First write the complete balanced equation for the reaction between calcium carbonate (CaCO3) and hydrochloric acid (HCl) the products of the reaction are calcium chloride, carbon dioxide and water. What is the sum of the coefficients when 5“ (\y M sumac. the reaction is balanced? a. 8 camp} + («we my ducal «(— CoZ d. 10 . . .r Hip e 9 UM Cillxawwaéhfwlx ~> 64Kc M Q Ll‘u .L CLi 8. What is the mange oxidation state of sulf-ur—insmé'z? 7 9. W7 water is both: a. a reactant and the solute (9a reactant and the solvent c. a product and the solute d. a product and the solvent e. a liquid and the intermediate Name (Page 4 of 9) Exam 1 W Part II: Multiple Choice, Short Calculations (6 points each) Select the best answer and enter your choice on the cover sheet - No partial credit 10. The element Ge has 5 stable isotopes. The mass in amu and percentage of some are: 6992M” -’ v” <93 1‘1“2«5> * 9 W ‘2») .94 32 71.92 amu .2 , fl 1 W K. a 72 qmu “f t 27’3" 6‘ “r " 6 ( 1‘53 “'2' at); . . o .m '7 7 f'" 73.92 amu 36.54% 9.2. 9 a, ° “X (66 7 y s ’ w; m 75.92 amu 7.76/0 1 1‘23» a,“ 2) T 312‘ {.9 What are the percentages of the 2 missing isotopes? 0. 20.5270 Ge-70 and 27.43% Ge-72 at?” 134‘ ‘1‘» b. 27.43% Ge-70 and 20.52% Ge-72 I'f‘éflftgk {5 c. 31.52% Ge—7O and 16.43% Ge-72 w... B Cy "31:11.11 3', 1 d. 40.32% Ge-7O and 7.63% Ge-72 7“ {53‘3- 1» iii ‘1- 5 f “j 9 if it ’ i ‘7’) e. 1&52% Eve-70 and2££=3J°o 66—72 ‘3“ L" 3" l J t 1 My 0 3 I, f * ~ 1 o —— 12.91 $.72 seem “919:2 -Hééowé’“ 3“? 11. How many iron atoms are present in 25 molecules of F2203? \‘M :3 ‘” ‘15“, r?) " DJ M 1...) " 3* 3- 1 <5 i 3 >4 *7" 2 <3 i * W. a ‘7“ a. 3.01 x 1025 2 b. 1.50 x 1025 ' ’3" ~ Effl 53'" “iv L47 <~ Moi/C- xlfi"i”2.Q 3 l d. 25 1 .,.M%W 539 x: {I x L)“ y... e. 2.08 x 1013 3 051111. 91 2.1.11... 12. How many grams of anhydrous HBr are there in 250 mL of 35.9% by mass HBr(aq) with a density of 1.189/mL? ‘1- 295 Z ’50 M I» iii b. 89.7 . 1 1,\ L; 9 “ 1.132;) 2:35:91... '7 c. 822 1” d 76.1 Name (Pa e 5 of 9) Exam 1 <1 9:20 3:5, and (x k We ‘0 Am (.0: i: u) Mfi u; '\ wk.i."”\1~.u€.,¢1,4, l w ‘3 . l .3 ‘03 M‘i ("(7. (at; )6 a. 1.12x1024 ’92.24 x 1024 c. 3.72 d. 1.86 e. 2.08 x 1013 14. Equal volumes of two aqueous solutions are mixed one containing 38.0 g of chloric acid per liter and the other is 0.80 M aqueous barium carbonate. What would be the molarity of barium chlorate in the final solution, assuming volumes were additive? “Molar mass of HClO3 = 84.458 g/mol BaCO3+2HClO3 ~> pagaoyz + 602 + H20 a. 0.10M Egg bio/K Ugly/vise; was»: My b. 0.20 i ,. , r!— K c 0 gal “- Mammy/u z: (4% 1le 1 l v 7. Ho: 7; @0.48M I my % g {44.103 3 Mfluxmdfl eflwMMH$fimfizungwrn . uu‘ L 5’4 (“(033 l L I BRCG? ' «m l. 25 WW‘LQ l‘mlg b531,. ” 1’» l l l W ’3 “(C6519 2%“ 15. Aluminum oxide is a ruff compound used to make sand paper: 4 Al(s) + 3 02(9) —> 2 Al203(s) If) a mixture of 40 g of aluminum and 38 g of oxygen produced 65.4 g of aluminum oxide, what was the percent yield? a. 81% dud-l“ 8‘ m “if, T ‘5? Vilma =1.) 4;; ,, i (Kg/U & = a E: Name (Page 6 of 9) Exam 1 Part III: Long Answers Please show all work for calculations - Partial credit may be given 16. (10 points) When a 6.72 gram sample of a carbon-hydrogen-nitrogen compound is burned completely, it yields 10.42 grams of COz(g) and 4.978 grams of H200) and some nitrogen oxides. What is the empirical Formula of the compound. A separate experiment shows that there are 6 moles of nitrogen in every mole of the compound. Determine: . a) The mass percent composition, 4’# b) The empirical formula, and :4> / c) The molecular formula of the compound. 4'7/ 0) Mass percent composition: 'v’) x. 1.9411 I’ ..- ,. ,e’ QC.) “ 5/ 2:1?2 C— 6 e 4216;. q. We a. a. o es: V.-- :_-.~ 5” H e V w 1 X4: 5'.) C) "1“ g! 1 3 51 7 L S) v) 2.7.47. c, 43,17. H, K/q‘é, °/. N Name 1 (Pa e 7 of 9) Exam 1 lam/C? <3; wall “>4 val-Ma b) Empirical Formula: 3, <2 m 9L... a , 34 3 xx? 3] .1 . , , '21133 >47 £7 a { 2: ’WQC" r» '— a ' " ,k I r” ( 2c ' l :3 7 w- L <3 I y 2 2 c) Molecular Formula: Name (Pa e 8 of 9) Exam 1 17. (9 points) We have 250 mL of 45.0% by mass HCl(aq) wi’rh a density of 1.15 g/mL. a) How many moles of HCI do we have? b) How many liTers of 6.00 M HCI can we prepare? c) What mass of The 45% solution would I need To make 500.0 mL of 0.20 M HCI? — a) Moles of HCI: 2 $6 M 4— CJ « g is: “X i w» 04» fif’a 3} , b) Lifers of 6.00 M HCI: j H Ci -»":~___i_k:_wmflmwmw ..__, fr“ 5%: fill,” c) Mass of HCI soluTion: x” f i V g / I”, ” / 7 ME” ‘ V . 1., ’ I, V” V a; v i .. {053 M D e A... %MJ~ é q z?” )(W/eigawwo x g~ ( ‘33 “\- 4/7 Name (Page 9 of 9) Exam 1 M 18. (9 points) Silicon has three isotopes. The mass number of the lightest isotope is 27.97u with 92.21% abundance, followed by 295i and then 29.97u with a 3.08% abundance. a) Calculate the exact mass (4 significant Figures) of the 29Si isotope in u. I q 2 2i (2 :99 :1} «r U “@722 x}: 0 Bo %‘\l\w~e¢:,~ \ i {floss (2.9%) "I; 2 S?» ,O (7 Mafia 2%.63‘6 W 492% (:72, 31W tit?) miacfiwfiéé'29fi 3M (l «fizzlwo‘308i t3 2555‘, 2: Z‘ii 2.. l «wow: aw a: a wig Ls. (Mic Lyekfk“ egg «as: b) Calculate the average weight of the atom in grams. J; L» *7 “324’” . ‘2 1“ (W...) \ l ' '7 I “a ‘ b? i { keypacgmxz ( WWH “1'3 3,. by mm“? Ms Em/pmfi c) Calculate the % by mass composition of the Si—28 isotope. ’ .7?__€:;S.Ef:fif-z 43 pm: em :1. 9 it Bl Va b 0 AZ 3 la 3 3/ 4 '7, d) Calculate the mass spectrometer ratio of Si—28 to C42. Z“, til—335: Mlqfis -— 2,33 ...
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This note was uploaded on 04/10/2010 for the course CHE 2a taught by Professor Tingguo during the Winter '08 term at UC Davis.

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KMT1s2 - \LQ. Last Name 3 First Name Lab Sec, # _; TA: ;Lab...

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