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Unformatted text preview: padilla (tp5647) HW12: Intermolecular forces II shear (52375) 1 This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points The properties of a given substance are gov- erned by various forces or interactions. Con- sider the following 4 forces or interactions: covalent bonding dispersion forces hydrogen bonding dipole-dipole interactions Which of the following correctly lists these four types of interactions/forces according to increasing strength (weakest to strongest)? 1. dispersion; hydrogen; dipole; covalent 2. hydrogen; dipole; covalent; dispersion 3. hydrogen; dispersion; covalent; dipole 4. covalent; hydrogen; dipole; dispersion 5. dispersion; dipole; hydrogen; covalent correct Explanation: London forces, dispersion forces, van der Waals or induced dipoles all describe the same intermolecular force. London forces are in- duced, short-lived, and very weak. Molecules and atoms can experience London forces be- cause they have electron clouds. London forces result from the distortion of the elec- tron cloud of an atom or molecule by the presence of nearby atoms or molecules. Permanent dipole-dipole interactions are stronger than London forces and occur be- tween polar covalent molecules due to charge separation. H-bonds are a special case of very strong dipole-dipole interactions. They only occur when H is bonded to small, highly electroneg- ative atoms F, O or N only. Covalent bonds are intramolecular forces and are stronger than intermolecular forces. 002 10.0 points Which intermolecular force do all molecules possess? 1. dipole-dipole interaction 2. covalent bonds 3. dipole moment 4. hydrogen bonding 5. dispersion forces correct Explanation: Dispersion forces are caused by a tempo- rary disruption of the electron cloud. Since all molecules possess an electron cloud, all molecules possess dispersion forces. 003 10.0 points In which of these compounds would you find ONLY dispersion forces existing between the molecules? I. CCl 4 ; II. CO 2 ; III. CH 2 Cl 2 ; IV. HBr. 1. I only 2. I and III only 3. III only 4. IV only 5. II and III only 6. I and II only correct 7. III and IV only 8. II only 9. II and IV only 10. I and IV only Explanation: A nonpolar covalent molecule would have only dispersion forces with another nonpolar padilla (tp5647) HW12: Intermolecular forces II shear (52375) 2 covalent molecule. 004 10.0 points Identify the kinds of intermolecular forces that might arise between molecules of cis- CHCl CHCl....
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This note was uploaded on 09/09/2009 for the course CH 302 taught by Professor Mccord during the Spring '09 term at University of Texas-Tyler.
- Spring '09