Mid-term 1 Solutions

Mid-term 1 Solutions - 1. [5 pts] Calculate the following...

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Unformatted text preview: 1. [5 pts] Calculate the following to the correct number of significant figures. (5.15 + 82.3) x (0.024 + 3.000) 8?”. is x vs gout) c) 264.30 d) 298 / .— a) 264 b) 264.3 e)2.6x102 2. [6 pts] Consider the date obtained for the length of an object as measured by three students. The length is known to be 14.54 cm. Which student has done the most precise determination? Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 a)“ 14.8 14.2 14.5 14.7 14.3 \ mt c___b) D 14.7 14.8 14.9 14.8 14.8 é—» “6:33:30 (:3 c) 14.3 14.2 14.8 14.9 14.8 ‘ ' 3. [6 pts] A mineral sample has a mass of 24.3 g and a volume of 3.5 cm3. The mineral could be sphalerite (density = 4.0 g/cm3), 9§§§ltgrjt§jden$i1yi§99 g/cm3) or cinnabar (density = 8.10 g/cm3). Which is it? assiterite » Lt a) sphalerite P: we if}: (0.3% V g, g 4. [6 pts] Which of the following statements is correct? a: 0th elements and compounds are pure substances. o Elements, but not compounds, are pure substances. 0) Compounds, but not elements, are pure substances. d) Neither compounds nor elements are pure substances. e) Compounds cannot be decomposed into elements. 5. [5 pts] Elements in Group 6A are known as the f l,’ . A) alkali metals \_.___8) chalcogens C) alkaline earth metals D) halogens E) noble gases 0) cinnabar 6—»— \ 6. [5 pts] Which pair of atoms constitutes a pair of isotopes of the same element? 19 A) 14 X 14 X D) 19 X X 6 7 10 9 ’B) 14X 12X W E) 20X 21X . 6 6 1o 11 C) 17X 17 X M 79Br- 7. [6 pts] The ion 35 contains: a) 35 protons, 44 neutrons, 35 electrons b) 35 protons, 44 neutrons, 34 electrons 44 protons, 35 neutrons, 36 electrons _ fl) 5 protons, 44 neutrons, 3_gelectrons Br M4 ow; am elf) c. NOR 8. [5 pts] What is the symbol for the sulfate ion? @ b) 3032' c) 3022' d803' e) 304' 9. [5 pts] What is the formula for titanium (IV) sulfide? a) TiS b)Ti82 " c) Tizs d) Ti4S e) TiS4 10. [5 pts] What is the chemical name of Ni(N03)2? a) nickel dinitrate b) dickel nitrogen oxide c) nickel nitrite d) nickel nitrate e) nickel nitride 11. [5 pts] What is the formula for perchloric acid? a)HClO b)HCIO3 c)HC@ d)HCIo2 e)Hcl -W/ 12. [6 pts] Balance the following equation. What is the sum of the coefficients of the reactants and products? 5 Ag + :2st + _02 —> :ZAng + 2—H20 a)14 b)12 [£311 d)10 e)8 \ VJ, \ ~._ 13. [7 pts] To three significant figures, what is percent of fluorine in cryolite, Na3AlF5? (Atomic weights: Na = 22.99, AI = 26.99, F = 19.00) e) 12.4 ’{V "f [CR :0 O \\L\ lOC) 14. [7 pts] A hospital patient is given a solution containing 9.00 x 10'9 g of iodine-131 (isotopic weight - 131). How many atoms of iodine are present? a) 1.36x109 b) 1.36x108 0) 4.14x1o15 (T5) 4.14x1013_) e) 6.68x1017 Ofivxulxzo‘“ Moms '5 m q.l‘l mo‘ 0%. 0M5 j. 15. [7 pts] When 0.880 g of an organic compound containing carbon, hydrogen and oxygen is burned completely in oxygen, 1.760 g of C02 and 0.720 9 H20 are produced. What is the empirical formula of the compound? (Atomic weights: carbon = 12.01, H = 1.008, O = 16.00) a) CHO b) cszo lo) C2H4Ol d) C3H602 e) ch604 Nico g (.07. 7‘ Egifig- = O‘WM’ ‘25 C" i QL§|m3w2 o . ll. '.'| I .‘.I.r-."I' ' ti‘: 16. [7 pts] A compound consists of 15.5% carbon, 23.0% chlorine and 61.5% fluorine by mass. What is the empirical formula of the compound? (Atomic weights: C = 12.01, CI = 35.45, F = 19.00) “x. a) CCIF b) C2CI2F C) C2C|F2 /d) C2C|F5 \l e) C2C|F3 .& . ~ Ovuwxm \ocz c\ \- p i' —- uc‘ =' ?. c \ is». e m 391?». l~2~°l ml 6.; "'“TC'EiCl ‘* L 8‘ "H \an ca C... .. c l t ‘ at x 13.0 o \ 13:919.- 0&0th y‘m-o‘ U 0,3? iii” \ 3 3§1Ll§ém 0.0: l \ if E C ‘1’ F" E wacgkl‘ Wwfl \“fi: EF‘VLE‘ r («Rota u ‘0‘ ’ ‘3’ (misath 3 Ox (2‘. ‘l f‘\ l w (:2 C...\ 17. [ipts] Calculate the number of moles of Fe304 produced from 0.75 moles of Fe by the following reaction. 3Fe + 4H20 —> F8304 + 4H2 a) 2.25 b) 0.75 c) 0.50 e) 0.15 .. Vic. Ch , v 'x t. ‘ ‘2; wol Fe 18. [6 pts] Which of the following setups is correct to calculate the number of moles of Clz required to produce 6 moles of PCI3 according to the following equation? BClz + P4 —> 4PC|3 a) 6 moles PCI3 x 6 moles PCI3 b) 6 moles PC|3 X 4 moles PCI3 4 moles Cl2 6 moles Clz 6 moles PCI3 X 6 moles Clz d) 6 moles PCI3 x 4 moles 0'2 4 moles PCl3 6 moles PCI3 Questions 19-21. The reaction of methane with chlorine produces carbon tetrachloride by the following reaction CH4 (9) + 4 Cl2 (g) —> CC|4 (l) + 4HCl(g) [MW 1 3 com :2. Hewett > C112“ ~70. cw) Cam :1 kg?“ m) Hm, 3mg 19. [6 pts] When 100.0 g of CH4 and 400.0 g of Clg are allowed to react, what is the limiting reagent? 8) CH4 9‘ b) Clg c) CCl4 d) HCI e) there is no limiting reactant 5mm: -- Wu v‘ T ‘T‘E‘E‘ CH”- 1‘ “Li‘iwéé‘r‘l m 3., a be: '2; me i dig " 1‘ io .ollq \ Mel 0..th alz 2 LWQ 3 CA? y \fch Ch q ,LJ‘fl‘ l V Uii Wm\ C C ‘Lf ,\ “at—magma H w m a? 20. [6 pts] How many moles of excess reagent remain after completion of the reaction? 1 604.83 mol b) 6.23 mol 0) 1.41 mol d) 1.55 mol e) 5.64 mol l . 1A4; "J Lu Cite: (0.2%, mlCHq ‘31 ‘ l“ \' f‘. K 'r a. me“? M31.) . I Q m r e r b lolll Mtol Mum, V at “vs q f8 2 w O l ('0 w 00% 21. [7 pts] How many grams of CCl4 can form under these conditions? MW: CCI4= 153.82 g/mol human-L. a)22.6g b)738g c)54.2g d)185g le)217gl 22. [7 pts]GeF3H is formed from GeH4 and GeF4 in the combination reaction: GeH4 + 3GeF4 —) 4GeF3H If GeH4 is the limiting reactant, what is the theoretical yield starting with 100 g of GeH4? (MW: GeH4 = 76.64 g/mol, GeF4 = 148.60 g/mol, GeF3H = 130.61 g/mol) a)170g b)511g c)439 d)682g e)117g 23. [7 pts] For the formation of GeFaH given below, lab experiments show that the reaction yield is 92.6%. How many moles of GeF4 are needed to produce 8.00 mol of GeF3H? GeH4 + 3GCF4 —> 4GeF3H a) 3.24 mol b) 5.56 mol I '_'= C) 6.48 mo! d) 2.78 mol e) 2.16 mol “liar mos.) we: ‘28 Wool. 6.6 "EH fl 24. [5 pts] Which of the following are strong electrolytes? HCI \/ HC2H302 NH3 KCI »/ La) Hgfia 657%, NH3 , KCl 0) HCI, HC2H302, NH3, KCI d) HCI, HC2H302, KCI 9) HC2H302 . KCI 25. [5 pts] A weak electrolyte exists predominantly as -‘ in solution. a) atoms b ions 0 molecules d) electrons e) an isotope 26. [6 pts] When the following aqueous solutions where mixed which pair gave a precipitate? a) HBr + KOH => 0) PbN03 + SF(CzH302)2 d) NaOH + HCzH3Oz e) NH3 + HCI 27. [6 pts] When sulfuric acid is neutralized by sodium hydroxide in aqueous solution, the net ionic equation is C.» . A , r .; 1&4) 6):?)11 x; ("A B§;."~\“’U'y‘ is) t‘ ‘ | - ' V ‘ , l l ,. l, e» ‘1 0 a) 3042 (aq)+2Na+ (aq) —> Na2SO4 (aq) N A" O H to a. «a PM“ if, z b) 8042' (aq>+2Na+ (a9) a Na2304 (s) .- 3, \x m lQ\ ~4w__. Wat—r. “.0. -' I; ' -44 V l c) H+ (aq)+OH' (aq) —> H20 (1) \ éA l 63 5 l lMd") H231); (Ag) + on' (aq) —> H20 (1) + 3042' (aq) e) 2H+ (aq) + 2NaOH (aq) —> 2H20 (1) + 2Na+ (aq) 28. [6 pts] Calculate the molarity of a solution of 91 g of MgClz in 2.0 L of solution. a: .1, of (Atomic weights: Mg = 24.30, CI = 35.45) ‘l‘flq 1‘ l s *1 '2‘1z'é 3* *l ’0 'nl 0 L" ‘ ' 3 ,dw" ‘ ‘ a) 0.18 b) 0.24 [0) d) 0.96 e) 1.2 M ml _§:1873:\M::s. .. l“ 3}: ll i w " 3 ' L; gollk - II 1 "‘3an . . . .r ':' i?" i; i‘-\ 29. [5 pts] What is the oxidation state of Cr in the compound Cr(OH)3? it: ' ‘13 a) +2 L . i b] +5 0 ‘ 0) +1 _ End) +3 '. e) it is neutral 30. [é points] Which of the following would require the largest volume of 0.100 M sodium hydroxide solution for neutralization? [NJ 3 W”, ...... --~~r ~ 7 r i -- -- a, . _. .3; m. E) 10.0 mL _of 0,05OQMphOSphoric acid } “zfl'j‘l 3 “t 0 ‘ 0 § "V m \ 0 ml bfido mL of0.0500 M nitric acid H No 3 i K O .og i yo -=' l‘ l c) 5.0 mL of 0.0100 M sulfuric acid H250 Li 2 A D ‘ 0‘ y :5 :- [)9 lo M" d) 15.0 mL of 0.0500 M hydrobromic acid \l \lifi" \A o ‘ Qty 9 t‘S -= o Elf“ e) 10.0 mL of 0.0500 M perchloric acid rt CWQH \ 1 Q i as; g is.) : £33.; \iiol LHsLasi" [Hf] .chawi‘r’és {PI/£057 NR0” 6e 1941843057 Vow 0.! M MMOH ...
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This note was uploaded on 04/18/2008 for the course CHEM 121 taught by Professor Loza during the Spring '08 term at A.T. Still University.

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Mid-term 1 Solutions - 1. [5 pts] Calculate the following...

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