CHM 114 A/C Take-Home Quiz #5 KEY 1. (2 pts) (a) Which of the following is the correct order of increasing boiling point? A. (a) < (b) < (c) B. (a) < (c) < (b) C. (b) < (a) < (c) *D. (b) < (c) < (a) E. (c) < (a) < (b) F. (c) < (b) < (a) (b) Explain your reasoning in part (a): •Molecule (b) has the lowest boiling point since it is nonpolar and is lowest in mass: It has the weakest London Dispersion forces.•Molecule (a) has the highest boiling point because it has hydrogen bonding.2. (2 pts) Which should have the higher vapor pressure at 25°C, CCl4or CBr4? CCl4Explain: The substance with the weakest intermolecular forces has the greatest vapor pressure. Both are nonpolar with only London-Dispersion forces. CCl4has the lowest mass and therefore the weakest London-Dispersion forces. 3. (1 pt) Describe what happens to average molecular velocity when each of the following changes occurs to a gas. (a) Temperature is increased (constant V and n). Average velocity increases.(b) Volume is reduced (constant T and n). Average velocity does not change.
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This note was uploaded on 01/27/2010 for the course CHM 71476 taught by Professor Marks during the Spring '10 term at ASU.