H10- Gases 2-solutions

H10- Gases 2-solutions - goldstein (ddg625) H10: Gases 2...

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Unformatted text preview: goldstein (ddg625) H10: Gases 2 mccord (50970) 1 This print-out should have 22 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points What is the mass of oxygen gas in a 11.0 L container at 23.0 C and 3.88 atm? Correct answer: 56 . 2004 g. Explanation: T = 23 . C + 273 = 296 K P = 3 . 88 atm V = 11 L m = ? n = P V RT = (3 . 88 atm)(11 L) ( . 0821 L atm mol K ) (296 K) = 1 . 75626 mol O 2 m = (1 . 75626 mol) parenleftbigg 32 g mol parenrightbigg = 56 . 2004 g O 2 002 10.0 points Toluene (C 6 H 5 CH 3 ) is a liquid compound similar to benzene (C 6 H 6 ). Calculate the mole fraction of toluene in the solution that contains 126 g toluene and 64.0 g benzene. Correct answer: 0 . 626. Explanation: m toluene = 126 g m benzene = 64.0 g n toulene = (126 g toluene) parenleftBig 1 mol 92 . 14 g parenrightBig = 1 . 37 mol n benzene = (64 . 0 g benzene) parenleftBig 1 mol 78 . 11 g parenrightBig = 0 . 819 mol The total number of moles of all species present is 1 . 37 mol + 0 . 819 mol = 2 . 19 mol The mole fraction of toluene is then X toluene = n toluene n total = 1 . 37 mol 2 . 19 mol = 0 . 626 003 (part 1 of 4) 10.0 points Iron pyrite (FeS 2 ) is the form in which much of the sulfur exists in coal. In the combustion of coal, oxygen reacts with iron pyrite to produce iron(III) oxide and sulfur dioxide, which is a major source of air pollution and a substantial contributor to acid rain. What mass of Fe 2 O 3 is produced from the reaction is 65 L of oxygen at 4 . 28 atm and 164 C with an excess of iron pyrite? Correct answer: 225 . 245 g. Explanation: P = 4 . 28 atm T = 164 C + 273 = 437 K R = 0 . 08206 L atm K mol V = 65 L MW Fe 2 O 3 = 2(55 . 845 g / mol) + 3(15 . 9994 g / mol) = 159 . 688 g / mol The balanced equation is 4 FeS 2 (s) + 11 O 2 (g)- 2 Fe 2 O 3 (s) + 8 SO 2 (g) Applying the ideal gas law to the O 2 , P V = nRT n = P V RT = (4 . 28 atm) (65 L) ( . 08206 L atm K mol ) (437 K) = 7 . 7579 mol . From stoichiometry and the molar mass of Fe 2 O 3 , m Fe 2 O 3 = (159 . 688 g / mol Fe 2 O 3 ) 2 mol Fe 2 O 3 11 mol O 2 (7 . 7579 mol O 2 ) = 225 . 245 g Fe 2 O 3 . 004 (part 2 of 4) 10.0 points If the sulfur dioxide that is generated above is dissolved to form 7 . 4 L of aqueous solu- tion, what is the molar concentration of the resulting sulfurous acid (H 2 SO 3 ) solution? Correct answer: 0 . 762447 M. goldstein (ddg625) H10: Gases 2 mccord (50970) 2 Explanation: V = 7 . 4 L SO 2 (g) + H 2 O( )- H 2 SO 3 (aq) . From the stoichiometry, n SO 2 = (7 . 7579 mol) parenleftbigg 8 n SO 2 11 n O 2 parenrightbigg = 5 . 64211 mol ....
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H10- Gases 2-solutions - goldstein (ddg625) H10: Gases 2...

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