Copy (50) of exam_1a_2008_1_soln - NAME:_____ _SOLUTIONS __...

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Unformatted text preview: NAME:_____ _SOLUTIONS __ ____ Chem 1a, first examination Show your work in all problems to receive credit. A periodic table with useful data is included as an insert. You may use the back for scratch work but enter ALL work to be graded in the space provided with each question. 1) (65 points) Combustion, i.e. reaction with O 2 , is often used to dispose of chemical wastes. The combustion of methyl amine, CH 3 NH 2 , yields nitrogen monoxide, carbon dioxide, and water. a) Write a balanced equation for the oxidation of methyl amine. 4 CH 3 NH 2 (l) + 11 O 2 (g) → 4 NO(g) + 10 H 2 O(g) + 4 CO 2 (g) b) Calculate the mass of water produced from the complete combustion of 55 g of methyl amine. M(CH 3 NH 2 ) = 1(12) + 5(1) + 1(14) = 31 g/mole M(H 2 O) = 1(16) + 2(1) = 18 g/mole n(CH 3 NH 2 ) = (55 g)/(31 g/mole) = 1.77 mole n(H 2 O) = (10/4) n(CH 3 NH 2 ) = 4.44 mole m(H 2 O) = (4.44 mole)(18 g/mole) = 80. g (8.0 x 10 1 g) c) Calculate the number of molecules of O 2 required for the combustion. n(O 2 ) = (11/4) n(CH 3 NH 2 ) = 4.88 mole N(O 2 ) = N A n(O 2 ) = (4.88)(6.02 x 10 23 ) = 2.9 x 10 24 molecules d) The engineer handling a disposal facility is provided with 5,000 L of an aqueous solution of methyl amine. In order to determine the concentration of methyl amine, the engineer collects a 25.00 mL aliquot of the solution and titrates methyl amine, the engineer collects a 25....
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This note was uploaded on 12/02/2009 for the course CHEMISTRY chemistry taught by Professor Chemistry during the Fall '09 term at University of Massachusetts Boston.

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Copy (50) of exam_1a_2008_1_soln - NAME:_____ _SOLUTIONS __...

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