Supplemental Problems 2009

Supplemental Problems 2009 - Chemistry 111 supplemental...

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1 Chemistry 111 supplemental problems not found in the text. These problems are adapted from Chemical Thermodynamics, An Introduction , by J. Rex Goates and J. Bevan Ott, Principles of Modern Chemistry by Oxtoby, Gillis and Nachtrieb, and Chemical Principles by Steven S. Zumdahl S1. Calculate the number of atoms of silicon (Si) in 415 cm 3 of the colorless gas disilane at 0 C and atmospheric pressure, where its density is 0.00278 g cm -3 . The molecular formula of disilane is Si 2 H 6 . S2. At its boiling point (280°C) and at atmospheric pressure, phosphorus has a gas density of 2.7 g L -1 . Under the same conditions nitrogen has a gas density of 0.62 g L -1 . How many atoms of phosphorus are there in one phosphorus molecule under these conditions? S3. From the following information below, determine the mass of substance C that will be formed if 45.0 g of substance A reacts with 23.0 g of substance B. (Assume that the reaction between A and B goes to completion.) a. Substance A is a gray solid that consists of an alkaline earth metal and carbon (37.5% by mass). It reacts with substance B to produce substances C and D. Forty million trillion formula units of A have a mass of 4.26 mg. b. 47.9 g of substance B contains 5.36 g of hydrogen and 42.5 g of oxygen. c. When 10.0 g of substance C is burned in excess oxygen, 33.8 g of carbon dioxide and 6.92 g of water are produced. A mass spectrum of substance C shows a parent molecular ion with a charge-to-mass ratio of 26. d. Substance D is the hydroxide of the metal in substance A. S4. A newspaper article about the danger of global warming from the accumulation of greenhouse gases such as carbon dioxide states that “reducing driving your car by 20 miles a week would prevent release of over 1000 pounds of CO 2 per year into the atmosphere.” Is this a reasonable statement? Assume that gasoline is octane (molecular formula C 8 H 18 ) and that it is burned completely to CO 2 and H 2 O in the engine of your car. Facts (or reasonable guesses) about your car’s gas mileage, the density of octane, and other factors will also be needed. S5. A mixture of aluminum and iron weighing 9.62 g reacts with hydrogen chloride in aqueous solution according to the parallel reactions 2 Al + 6 HCl → 2 AlCl 3 + 3 H 2 Fe + 2 HCl → FeCl 2 + H 2 A 0.738 g quantity of hydrogen is evolved when the metals react completely. Calculate the mass of iron in the original mixture. S6. A 1.37 M aqueous solution of citric acid (H 3 C 6 H 5 O 7 ) has a density of 1.10 g/cm 3 . What are the mass percent, molality, and mole fraction of the citric acid? S7. A solution is made by dissolving 25 g of NaCl in enough water to make 1.00 L of solution. Assume that the density of the solution is 1.00 g/cm 3 . Calculate the mass percent, molarity, molality, and mole fraction of NaCl. S8.
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This note was uploaded on 02/01/2011 for the course BIO 2020 taught by Professor Kropf during the Spring '11 term at University of Utah.

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Supplemental Problems 2009 - Chemistry 111 supplemental...

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