Chem 162-2011 Exam 3 + solutions

Chem 162-2011 Exam 3 + solutions - CHEM 162-2011 EXAM III +...

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CHEM 162-2011 EXAM III + SOLUTIONS Chem 162-2011 Exam III + Answers Chapter 22 - Transition Metals and Coordination Chemistry Coordination Compounds 1. Which of the following is called a chelating ligand? A. NO 2 - B. CN - C. CH 3 CH 2 CH 2 NH 2 D . - OOCCOO - E. NH 3 A chelating ligand is one that is polydentate, and has the non-bonding electron pairs far enough apart, so it can form a ring. A. No. Although NO 2 - can attach at both the N and O, the non-bonding electron pairs are too close together to form a stable chelate with the metal cation. It would form a relatively unstable three-membered ring. B. No. Although CN - can attach at both the C and N, the non-bonding electron pairs are too close together to form a stable chelate with the metal cation. It would form a relatively unstable three-membered ring. C. No. The CH 3 CH 2 CH 2 NH 2 can only attach at the nitrogen. A chelating ligand must have at least two non-bonding electron pairs for two attachments to the metal cation. D. Yes. Oxalate ion is well known for forming a chelate. It is bidentate, and can form a stable five membered ring. E. No. The NH 3 molecule can only attach at the nitrogen. A chelating ligand must have at least two non- bonding electron pairs for two attachments to the metal cation. Chem 162-2011 Exam III + Answers Chapter 17 - Thermodynamics Entropy Concepts 2 . What effect does hydrogen bonding in the liquid phase have on the entropy of vaporization? A. Hydrogen bonding causes the entropy of vaporization to always equal zero. B. Entropy of vaporization is not measurable, when hydrogen bonding is present C. Hydrogen bonding decreases the entropy of vaporization. D. Hydrogen bonding does not affect the entropy of vaporization. E . Hydrogen bonding increases the entropy of vaporization. It is assumed that a substance in the gas phase is an ideal gas, i.e., there is no interaction between the molecules. If there were no hydrogen bonding in the liquid phase, e.g., hexane-hexane bonding, then there would be a certain increase in positional freedom in going from the liquid phase where there is moderate positional freedom, to the gas phase, where there is much more positional freedom. However, if there were hydrogen bonding in the liquid phase, e.g., CH 3 OH and CH 3 OH, then there would be relatively low positional freedom in the liquid phase. Therefore, the change in positional freedom (i.e., the change in entropy) would be greater in going from the liquid phase to the gas phase as compared to hexane and hexane making the same transition. This is the cause of deviation in Trouton’s Law for polar solvents. 1
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Chem 162-2011 Exam III + Answers Chapter 22 - Transition Metals and Coordination Chemistry Coordination Compounds 3 . What is the correct formula for the diamminetetracyanocobaltate(III) ion? A. [Co(CN)(NH
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This document was uploaded on 11/02/2011 for the course GEN CHEM 162 at Rutgers.

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Chem 162-2011 Exam 3 + solutions - CHEM 162-2011 EXAM III +...

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