Tutorial 1 a - CHEM 1A03 TUTORIAL #1 September 14-18, 2009...

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CHEM 1A03 TUTORIAL #1 September 14-18, 2009 Solutions – Assumed Knowledge ________________________________________________________________________ Page 1 of 4 The Following Questions Are Based on Assumed Knowledge: Ch 1, 2, 3, 4 & 6 1. A sample of a noble gas has a mass of 0.102 g and exerts a pressure of 0.242 atm in a 0.260 L vessel at 27 o C. Is the gas He, Ne, Ar, Kr, or Xe? To determine which gas is in the sample, we must determine the molecular mass of the gas. This can be done with the ideal gas law: PV = nRT = (m/M)RT where m = the mass of the gas in grams, and M = molar mass of the gas in grams/mol. Solving for M, one gets M = mRT/(PV) = (0.102 g)(0.0821 L atm K 1 mol 1 )(300 K) / (0.242 atm)(0.260 L) M = 39.9 g/mol; the gas is argon . 2. A 0.02864 g sample of vitamin A, a compound consisting only of carbon, hydrogen, and oxygen, is burned to form 0.08802 g of carbon dioxide and 0.02703 g of water. Calculate the percentage of each element in vitamin A. Mass of C in vitamin A = 0.08802 g CO 2 (12.01 g C)/(44.01 g CO 2 ) = 0.02402 g C Mass of H in vitamin A = 0.02703 g H 2 O (2.016 g H)/(18.016 g H 2 O) = 0.003025 g H Mass of O in vitamin A = total mass of vitamin A - mass of C - mass of H = 0.02864 - 0.02402 - 0.003025 = 0.00160 g O % C = (0.02402 g C)/(0.02864 g sample) 100 % = 83.87 % C % H = (0.003024 g H)/(0.02864 g sample) 100 % = 10.56 % H % O = (0.00160 g O)/(0.02864 g sample) 100 % = 5.59 % O 3. Acrolein is a reactive and toxic unsaturated aldehyde that is used in the polymer industry that contains 64.3% carbon, 7.2% hydrogen, and 28.5% oxygen by mass. a) Calculate the empirical formula for acrolein. The formula has general form C
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This note was uploaded on 01/16/2010 for the course CHEMISTRY 1A03 taught by Professor Dr.p.lock during the Fall '08 term at McMaster University.

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Tutorial 1 a - CHEM 1A03 TUTORIAL #1 September 14-18, 2009...

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