Exam III Worked Out Solutions

# Exam III Worked Out Solutions - Solutions 1 Exam 3 Fall...

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Solutions Exam 3 Fall, 2008 1. An orbital is mathematical function which is a solution of the Schrödinger equation. The function is designated by the Greek letter ψ (psi), and the probability of finding the electron is proportional to ψ 2 . Choice A 2. 1,3 dibromobenzene consists of a benzene ring in which two of the hydrogens are replaced by bromines. A benzene ring has alternating single and double bonds: each single bond is a σ bond, and each double bond has one σ bond and one π bond. Thus within the ring itself, there are 6 σ bonds and 3 π bonds. In addition, each carbon atom is attached by a sigma bond to either hydrogen or bromine. This makes for 6 more σ bonds. Total: 12 σ bonds and 3 π bonds. Choice E 3. N 2 H 4 has one N-N single bond and four N-H bonds. 2F 2 has 2 F-F bonds Bond energy of the reactants: 1(163) + 4(389) + 2(159) = 2037 kJ/mol N 2 has one N-N triple bond. 4 HF has 4 H-F bonds Bond energy of the products: 946 + 4(565) = 3206 kJ/mol H = Σ (bond energy of reactants) - Σ (bond energy of the products) H = 2037 – 3206 = -1169 kJ Choice E 4. E = h ν = ηχ λ 368 κϑ μολ x 1000 ϑ κϑ x 1μολ 6.02ξ10 23 ατομσ = (6.626ξ10 -34 29( 3.00ξ10 8 29 λ Solving: λ = 3.25 x 10 -7 meters or 325 nm Choice D 5. Zn (atom, no charge) has configuration [Ar]3d 10 4s 2 Zn 2+ ion has configuration [Ar]3d 10 When forming a positive ion from a transition metal, the s electrons are removed first. Choice D 6. The structure of H 3 O + has a central oxygen with 3 single bonds and a lone pair of electrons. This would have a formal charge of +1 on the oxygen atom.

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The structure of NO 3 - has a central nitrogen with one double bond and two single bonds going to the three oxygen atoms around it. This would have a formal charge of +1 on the nitrogen atom. The structure of H 2 CO 3 would have a central carbon atom with a double bond to one oxygen atom, and two single bonds going to OH groups. This would have a zero formal charge on the carbon atom. The structure of N
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## This note was uploaded on 12/20/2010 for the course CHEMISTRY 161 taught by Professor Seigel during the Spring '10 term at Rutgers.

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Exam III Worked Out Solutions - Solutions 1 Exam 3 Fall...

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