#Chem 161-2007 Recitation Quiz 2

#Chem 161-2007 Recitation Quiz 2 - Chem 161-2007 Quiz 2...

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Unformatted text preview: Chem 161-2007 Quiz 2 Version A1 1. The density of a gas was measured at 1.5 atm and 27 o C and found to be 1.95 g/L. Calculate the molar mass of the gas. 2. In the chemical reaction used in automotive air-bag safety system, N 2 (g) is produced by the decomposition of sodium azide: 2 NaN 3 (s) → 2 Na(s) + 3 N 2 (g). What mass of NaN 3 must be reacted to inflate an air-bag to 35.9 L at 25 o C and 0.980 atm? [Molar mass Na: 22.99; N: 14] 3. In 20 words or less define: a) Partial pressure b) Gas pressure in terms of Kinetic-Molecular Theory c) Diffusion Chem 161-2007 Quiz 2 Version A2 1. In 20 words or less define: a) Partial pressure b) Gas pressure in terms of Kinetic-Molecular Theory c) Diffusion 2. In the chemical reaction used in automotive air-bag safety system, N 2 (g) is produced by the decomposition of sodium azide: 2 NaN 3 (s) → 2 Na(s) + 3 N 2 (g). What mass of NaN 3 must be reacted to inflate an air-bag to 35.9 L at 25 o C and 0.980 atm? [Molar mass Na: 22.99; N: 14] 3. The density of a gas was measured at 1.5 atm and 27 o C and found to be 1.95 g/L. Calculate the molar mass of the gas. Chem 161-2007 Quiz 2 Version B1 1. In 20 words or less define: a) Partial pressure b) Gas pressure in terms of Kinetic-Molecular Theory c) Effusion 2. If a fixed amount of gas occupies 2.53 L at a temperature of -15 o C and 191 Torr, what volume will it occupy at 25 o C and 1141 Torr? 3. Oxygen can be produced in the laboratory by the following reaction: KClO 3 (s) → 2KCl(s) + 3 O 2 (g) How many grams of KClO 3 are needed to produce 2.75 L of oxygen at 28 o C and 1.1 atm? [Molar mass K = 39.1, Cl = 35.45, O = 16] Chem 161-2007 Quiz 2 Version B2 1. If a fixed amount of gas occupies 1.78 L at a temperature of -18 o C and 218 Torr, what volume will it occupy at 27 o C and 1255 Torr? 2. In 20 words or less define: a) Partial pressure b) Gas pressure in terms of Kinetic-Molecular Theory c) Effusion 3. Oxygen can be produced in the laboratory by the following reaction: KClO 3 (s) → 2KCl(s) + 3 O 2 (g) How many grams of KClO 3 are needed to produce 4.25 L of oxygen at 25 o C and 1.2 atm? [Molar mass K = 39.1, Cl = 35.45, O = 16] Chem 161-2007 Quiz 2 Version C1 Correction: Change “an atmospheric pressure” to “a pressure”. Correction: In definition question, compare an “open” system or “closed” system to an “isolated” system. 1. What is the mass of H 2 produced if 45.56 mL of H 2 are collected over water at 21.0 o C and an atmospheric pressure of 0.977 atm. [Vapor pressure of water at 21 o C = 21 Torr, Molar mass of H = 1.008] H 2 0.04556 L 294K P H2O = 21 Torr x (1 atm/760 Torr) = 0.0276 atm P H2 + P H2O = P Total P H2 + 0.0276 atm = 0.977 atm; P H2 = 0.949 atm M = 2.016 g/mol PV = nRT PV = (g/M)RT P = (g/VM)RT g = PVM/RT g = (0.949 atm x 0.04556 L x 2.016 g/mol)/(0.08206 Latmdeg-1 mol-1 x 294K) = 0.00361 g 2. Calculate ∆E if a system absorbs 675 J of heat and expands by 766 mL against a pressure of 577 Torr....
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This homework help was uploaded on 04/12/2008 for the course CHEM 161 taught by Professor Vacillian during the Fall '08 term at Rutgers.

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#Chem 161-2007 Recitation Quiz 2 - Chem 161-2007 Quiz 2...

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