Chem 210 spring 2009 Exam 2 (6)

Chem 210 spring 2009 Exam 2 (6) - Name: l Section: ID: F...

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Unformatted text preview: Name: l Section: ID: F (3313136 219 - Spring 2009 - Exam #2 Short Answer I. (2 points) Spell A.}.’s favorite word in chemistry: 4'0 Vick? 0 M. ‘5'? (Note: It describes the calculations of chemical quantities in reactions based 0 ole ratios.) 2. (6 points) What are the concentrations of chromium (III) ions and sulfate ions in a 0.50 M chromium (III) sulfate solution? {Cryrl ’11 )‘C’ ‘3 Multiple Choice (5 points each) Identifiz the choice that best completes the statement or answers the question. méfl 3. A 1-1.. bottle of a 3.33 M stock solution of NaBr is provided in the laboratory. If a procedure calls for you to prepare 500. mL of a 0.125 M NaBr solution, what volume of the stock solution wiil be required? A) 18.8 tnL B) 208 mL C) 12.5 mL D) 62.5 mi. E) none of these E 4. Selenio Acid has the formula H28e04. What is the formula for potassium selenite? A) KSeO4 B) K3603 C) K2320; D) K25802 E) K28603 % 5. What is the mass percent of NaCl in a solution prepared by mixing 15.0 g of NaCi with 90.0 g of water? A) 16.7 % ' B) 34.3 % C) 15.0 ‘Vo D) 85.7 % E) 18.3 % WE 6. What volume of {3.1107 M NaOH eoniains 10.0 g of NaOH (Mm 2 40.00 g/rnoi)? A) 4.43 L 8) M1 L C) 0.729 L D) 3.20 L E) 2.26 L 0' - Exam 2 Name: I Q Section: shame zoos S - FREE RESPONSE: Answer the foliowing questions in the spaces provided. Show aii work ami express fine} answers with the correct number of significant figures and units to receive foil credit. if you use exponential notation for your answer, you must use proper scientific notation, 7. (20 points) Write complete, balanced equations for the following chemical reactions. Be sure to include state symbols. if no reaction is expected, write NR and briefly expiain why. A) 13b5, + WA1C13(,q, 9 N K Q9; ;5 m meo&§ve » B) MTBE, a former gasoline additive with the formula, C5H120m, is burned. (Q CSH;)_Q(£‘) "'3‘ O} W (:3) C) iKOHtaq) + HgPOuaq) 9 G H (a) K 3) (W) D) Lithium metal reacts With oxygen in the air. 9 Lkm 4;— O‘MS) “"5 01 L505) 8. (12 points) Provide the names or formulas of the following compounds: 80;, 6 iflgwx 'L Y” {G‘fiifi—‘L hypochlorous acid Q } ZnBrz iivxg bm lead (N) hydroxide ?LD( 5 ii 2“, Ni3(P04)2 ammonium suifite SO; 3" .mwmw, 9. (fil’iii’ioints) Write the molecular and net ionic equations for the reaction of aqueous iron (III) sulfate with magnesium metal. MOLECULAR: I (Q . “m”? .2 it» a Ffiaé-E “2 3i! jig" 3 flgég} “g i {95:} 01 Rm NETIONIC: ' 3% 1%” .2, FEW 10. (10 points) An unknown compound contains only carbon and hydrogen. When a 2.000—g sample of the compound is analyzed, it is found to contain 1.810 g Carbon. The molar mass of the compound was detemined to be approximately 210 g mol in a separate experiment. What are the empirical and molecular formulas of the compound? ,EiiiiiZw‘éé} W“ - H ea fi’igir;w a“? M Wei“ 3 “" ng were 5 g mewwwir a.wv-V‘w_lww-y-s ry‘r‘y s-i‘vswmwueW-Jev‘w .WaW. ymmkmma A, _ 7 s H _ uv.‘u'uw~‘d:.wuv vwv'uwwvu h'wwv 1,‘ (8 points) Consider the teaction of tungsten (VI) oxide with hydrogen gas to form free tungsten metal. ' What mass of hydrogen gas will be required to quly react with 625 g of tungsten (VI) oxide? WO3{S} “f” 3 H38} "3‘ W“) + 3 H20“) Molar maSSES w a 183.84 {1, ’2” _ W“; a M “103223184 Hz a 2.02 H202 18.02 12. (15 points) In the lab a student mixes a solution containing 5.00 g sodium sulfide with a solution containing excess aqueous iron (1H) nitrate and a precipitate forms. If the reaction typicaliy proceeds with an 85.0 % yield, what mass of the solid product can the student expect to have when it is isolated? Salas/“l 2011.228in 3 a; +2?¢(NQ3)3 --—> pals} + Q Ma N03 5.003 “ma? (5) PM 2 7 days $003 heck Nun’s luau-IQ F1153, 3‘01 31 _ q 433 F $504 r4 .5 3.4:); “its " - :1 £953 3 5 it “13“?333 ® WM (m fl WW MW MM m”““’”“°~xc;;a * “a ,5 “tittifig X @3531; m 3131;13 fififig figs? (if; {geese gefifik‘é MWBWIWW v “WWWW «A, “fix BONUS: (3 points) Under an atmosphere of fluorine gas (no oxygen present), the compound CQHHNSz will burn in (react with) the fluorine gas to give only C135, HF, NE, and SFé. What is the balanced chemicai equation for this reaction? W § i Z < e i iCti-tieflétt “:3, RN we» iéeaefiiiaet W’g t. sga ww-wwmwwn a v'e'."u‘v.('u‘x‘-'\"-dwh'h via-w- ...
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Chem 210 spring 2009 Exam 2 (6) - Name: l Section: ID: F...

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