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Unformatted text preview: rathbun (rar2954) Homework 2 vanden bout (51640) 1 This print-out should have 28 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points Both ammonia and phosphine (PH 3 ) are sol- uble in water. Which is least soluble and why? 1. phosphine; the P- H bonds are so strong that they cannot break to enable phosphine to hydrogen-bond with water. 2. ammonia; the N- H bonds are so strong that they cannot break to enable the ammonia to hydrogen-bond with water. 3. ammonia; it does not form hydrogen bonds with water molecules. 4. ammonia; it is too small to be hydrated by water molecules. 5. phosphine; it does not form hydrogen bonds with water molecules. correct Explanation: PH 3 is least soluble because it cannot form hydrogen bonds with water. 002 10.0 points Some distilled water is added to an empty beaker. A gram of copper(II) nitrate is added to the beaker with stirring. After a few min- utes, what is in the beaker? 1. a sticky material of copper hydronitrite 2. nitrogen gas, copper atoms, electrons, and water 3. solid copper(II) nitrate and water 4. solid copper, nitrate ions, and water 5. copper ions, nitrate ions, and water cor- rect Explanation: All nitrates are soluble in water, so the cop- per(II) nitrate dissolves. Soluble ionic com- pounds are strong electrolytes, so the cop- per(II) nitrate also dissociates into its cation and anion parts: Cu + 2 and NO- 3 . 003 10.0 points Which is the best representation of the solva- tion of a sodium cation in water? hydrogen oxygen Na + ion 1. correct 2. rathbun (rar2954) Homework 2 vanden bout (51640) 2 3. 4. Explanation: Since the water molecule has a partial neg- ative charge on the O atom, it will orient itself to the O atom closest to the positively charged cation. 004 10.0 points When we put sugar in water it melts. 1. True 2. False correct Explanation: Sugar dissolves in water and melts when its temperature is raised above its melting point. 005 10.0 points Rank the following in terms of decreas- ing miscibility in C 8 H 18 (octane): C 2 H 5 Cl (chloroethane), H 2 O (water), C 2 H 5 F (fluo- roethane), C 9 H 20 (nonane). 1. C 2 H 5 F > H 2 O > C 9 H 20 > C 2 H 5 Cl 2. C 9 H 20 > C 2 H 5 Cl > C 2 H 5 F > H 2 O cor- rect 3. H 2 O > C 9 H 20 > C 2 H 5 Cl > C 2 H 5 F 4. C 2 H 5 Cl > C 2 H 5 F > H 2 O > C 9 H 20 Explanation: Octane is a non-polar solvent and thus ranking in terms of decreasing miscibility re- quires ranking in terms of decreasing non- polar character, i.e. from least to most polar. 006 10.0 points Octane (C 8 H 18 ) is a major component of gaso- line. Which of the following would you expect to be the LEAST soluble in gasoline?...
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