# 3 - Elbel Brittany Homework 3 Due Feb 6 2006 noon Inst J A...

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Elbel, Brittany – Homework 3 – Due: Feb 6 2006, noon – Inst: J A Holcombe 1 This print-out should have 22 questions. Multiple-choice questions may continue on the next column or page – fnd all choices be±ore answering. The due time is Central time. 001 (part 1 o± 1) 10 points Several interesting observations ±rom the world around you are listed below. Which o± these is NOT explained by a col- ligative property? 1. A lobster will die when placed in ±resh water. 2. Anti±reeze is added to a car radiator to keep the car ±rom overheating. 3. The ±reezing point o± water is lowered when salt is added. 4. Water boils at a higher temperature when salt is added. 5. At high altitude it takes longer to cook spaghetti. correct Explanation: Colligative properties o± a solution depend on the number o± solute particles in solution, not the type. Boiling point variations due to pressure changes have nothing to do with solutions and colligative properties (boiling point variations due to particles in solution, etc.). 002 (part 1 o± 1) 10 points Which o± the ±ollowing statements about col- ligative properties o± aqueous solutions is FALSE? 1. The higher the concentration o± solute in the solution, the higher the vapor pressure o± the solvent. correct 2. Osmosis is a colligative property. 3. For a given solution, the ±reezing point will be lowered more than the boiling point will be raised. 4. Colligative properties only depend on the number o± solute particles present in solu- tion. Explanation: Colligative properties, which include osmo- sis, vapor pressure lowering, melting and boil- ing point elevations, depend only on the num- ber o± solute particles present in solution, not on their properties. The e²ect on the melting point o± a given solution is less than the e²ect on its boiling point. With a higher concentration o± non-volatile solute the concentration o± the solvent in the solution is lower, causing the vapor pressure o± the solution to be lower. 003 (part 1 o± 1) 10 points Which o± the ±ollowing would likely dissolve in benzene? 1. Ca(HCO 3 ) 2 2. NaCl 3. Na 2 CO 3 4. Cl 2 CCCl 2 correct 5. C 6 H 12 O 6 Explanation: 004 (part 1 o± 1) 10 points Which o± the ±ollowing solutes is likely to be most soluble in water? 1. Br 2 2. carbon tetrachloride (CCl 4 ) 3. CS 2 4. ethanol (CH 3 CH 2 OH) correct Explanation: 005 (part 1 o± 1) 10 points Calculate the number o± moles o± oxygen that will dissolve in 45 L o± water at 20 C i± the par-

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Elbel, Brittany – Homework 3 – Due: Feb 6 2006, noon – Inst: J A Holcombe 2 tial pressure of oxygen is 0.21 atm. Henry’s constant for oxygen is 0.0013 mol L · atm . 1. 0.0013 mol 2. 0.00027 mol 3. 0.0062 mol 4. 0.012 mol correct 5. 0.28 mol Explanation: 006 (part 1 of 1) 10 points Calculate the molality of perchloric acid in 9.2 M HClO 4 (aq). The density of this solution is 1.54 g/mL. 1.
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## This note was uploaded on 06/23/2008 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas.

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3 - Elbel Brittany Homework 3 Due Feb 6 2006 noon Inst J A...

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