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# HW9S - Gauthier Joseph – Homework 9 – Due Nov 6 2007...

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Unformatted text preview: Gauthier, Joseph – Homework 9 – Due: Nov 6 2007, midnight – Inst: Vandenbout 1 This print-out should have 23 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. Room Assignments for EXAM 2 A-K WEL 1.316 L-O WEL 2.122 P-Z WEL 1.308 001 (part 1 of 1) 10 points Identify the kinds of intermolecular forces that might arise between molecules of trans- CHCl CHCl. 1. dipole-dipole 2. None of these 3. London forces, dipole-dipole, hydrogen bonding 4. London forces, dipole-dipole 5. London forces correct 6. hydrogen bonding Explanation: C H Cl C H Cl is non-polar. 002 (part 1 of 2) 10 points Calculate the ratio of the potential energies for the interaction of a water molecule with an Al 3+ ion (of radius 53 pm) and with a Be 2+ ion (of radius 27 pm). 1. . 39 correct 2. 0.24 3. 0.52 4. 0.76 5. None of these 6. 0.63 Explanation: r Al = 53 pm r Be = 27 pm The energy E p ∝-| z | μ r 2 , so the ratio is E Al E Be = | z Al | r 2 Be | z Be | r 2 Al = | 3 | (27 pm) 2 | 2 | (53 pm) 2 = 0 . 389284 003 (part 2 of 2) 10 points Which ion will attract a water molecule more strongly? 1. Al 3+ 2. Equal attraction 3. Be 2+ correct Explanation: The attraction of the Be 2+ ion will be greater than that of the Al 3+ ion. Even though the Be 2+ ion has a lower charge, its radius is much smaller than that of Al 3+ , making the attraction greater. 004 (part 1 of 1) 10 points Which of the following cations is likely to be hydrated in compounds? 1. Cs + 2. K + 3. Li + correct 4. Rb + 5. NH + 4 Explanation: Li + is the smallest. 005 (part 1 of 1) 10 points Gauthier, Joseph – Homework 9 – Due: Nov 6 2007, midnight – Inst: Vandenbout 2 Which of the following compounds is UN- LIKELY to be commonly available and thus not found in the laboratory? 1. BaCl 2 · 2H 2 O 2. KCN · 2H 2 O correct 3. La(NO 3 ) 3 · 6HO 4. Na 2 CO 3 · 10H 2 O 5. CuSO 4 · 5H 2 O Explanation: K + is only a +1 cation AND it is too large to substantially attract waters of hydration. +2 and +3 cations will generally form hydrates. Na + will also attract water due to its smaller size. 006 (part 1 of 1) 10 points What would be the most significant type of intermolecular forces in a liquid sample of fluoroform (CHF 3 )?...
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HW9S - Gauthier Joseph – Homework 9 – Due Nov 6 2007...

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