2005_Prelim_2_Key - 61.1 p411... Chem 216 Please do not...

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Unformatted text preview: 61.1 p411... Chem 216 Please do not open this examination until the TA's say you may do so. Please check that there are 3 questions in your exam. Problems 1 and 2 are on two pages each. Problem 3 is on a single sheet. The TA's have been told not to answer any questions during the examination period. If you finish the examination at least 15 minutes before the end of the exam you may turn the exam in. Otherwise please wait at your desk for your exam to be picked up by a TA. Please note this is a Chem 216 exam. F: i Name: Day of the week your lab meets: Question 1: Question 2: Question 3: TOTAL: s -18 eV while that of a carbon p lecule below. In the answer box ta. (10 pts) The energy of an oxygen p-orbital i se the indicated vectors in orbital is -12 eV. Consider the Ic-system oi the mo ' ' ' this tic-system. Please u please write the Hamiltonian for expressing your Hamiltonian as a matrix. Assume, as we did in class, that interactions between all b interactions between unbonded atoms. O\C—‘_C/O H/ \H equal to B and that there are no ;;-;i;es_$ize;;t.s:e,.,..,,_,-; ,t"§._A_‘_ : __ 1b. (18 pts) Let x and y be real positive numbers and assume x and y are not equal to one another. Consider the n—molecular orbitals of the molecule illustrated in Problem ‘la. As in the previous problem we define the individual atomic orbitals as follows: Whigh of the following can not be energy eigenvectors for any positive value of x or y. 2a. ( 10 pts) Consider the n—molecular orbitals of the molecule illustrated below. rfectly square shape. In class when we derived the Assume the molecule has a pa 'dered the two mutually perpendicular mirror MO diagram for this molecule we cons: planes illustrated in the middle drawing. Please now use the alternate set of mutually perpendicular mirro r planes indicated on the drawing on the right. H H \CMC/ M / \ H H s, draw the n—molecular orbital diagram in the With respect to these new mirror plane electrons filling each orbital. box provided below. Please indicate the number of ANSWER: ‘\: ":43: 5:21: ~ - 21:: '1 “:C'? at as r .q A r. us “is 7: ... 2b. (25 pts) Consider the tr-molecuiar orbitals of the molecule illustrated below. Assume the center ring oi the molecule has a perfectly square shape. Just as we considered in class, consider the perturbation of the 0-H o—bonding orbital (illustrated on the right) on the n—MO diagram. in the box provided below draw this perturbed rt-MO diagram, indicating the number of electrons filling each orbital. 2c. (5 points) Based on your MO diagram, indicate the most probable site for attack by H”. State succinctly your reasohing for this answer. 3. (32 pts) Consider the n~molecuiar orbitals of the molecule illustrated below. In the box provided below please draw its n~M0 diagram, indicating the number of . electrons filling each orbital. ENERGY 3b, ( 6 points) Based on your MO diagram, indicate the most probable site for attack by H“. State succinctly ur reasoning for thi newer. ' «CW 1 art» ~-~/ New Ace wow as it“; .: :.‘._:.._:~¢_>Q:..a "1—53?" ::w.u.5..«h....~wuw...~ mm; “0:, d it p, «1’ ‘2 5. (25 pts) The rt—MO diagram for molecule a, illustrated below, is also shown below. Energy An electron starts off in the orbital, 2 . If one measmes the energy compare the probability it is found to be in the states ‘1’1 , ‘1’2, “113, or ‘P4 ? If two probabilities are equal, please state that they are equal. ANSWER BOX: least probable most probable uare cyclobutadiene is shown below. An electron is initially in the state ‘1’. The energy is then measured. What are the possible energies measured in this case? For each energy what are the corresponding probablities? What is the average measured energy? 6. (25 pts) The n—MO diagram for sq ANSWER BOX: ...
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This note was uploaded on 03/29/2008 for the course CHEM 2160 taught by Professor Lee, s during the Spring '08 term at Cornell University (Engineering School).

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2005_Prelim_2_Key - 61.1 p411... Chem 216 Please do not...

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