test 2 - Version 092 Exam 2 McCord(53130 This print-out...

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Version 092 – Exam 2 – McCord – (53130) 1 This print-out should have 31 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. McCord CH301tt This exam is only For McCord’s Tues/Thur CH301 class. IF Quest works properly, you should be able to see your score For this exam by 11:30 PM tonight. Do realize however that Quest has been taking up to 8 hours to get through the grading, so your score might appear bit by bit. I will post an announcement on our web page and/or Quest when I Feel like all bubblesheets have been graded. PLEASE carefully bubble in your UTEID and Version Number! We av- erage about 20-30 students per exam that misbubble this inFormation. Get it right! 001 10.0 points Predict the bond angle in the nitrite ion, NO 2 . 1. 90 degrees 2. slightly less than 109.5 degrees 3. slightly less than 120 degrees correct 4. 60 degrees 5. 180 degrees 6. slightly less than 180 degrees Explanation: N is the central atom. One O atom makes a single bond to N and the other makes a double bond to N. This means there are TWO di±erent resonance structures. Additionally there is a lone pair on the N atom. There are 3 RHED around N so the elec- tronic geometry is trigonal planar. As one RHED is a lone pair, the molecular geometry is bent and the O-N-O bond angle is a little less than 120 degrees. 002 10.0 points Assume that in each pair oF compounds be- low the type oF crystal structure is similar. Consider the strength oF the attractive Force bonding the ions together in each compound. In which case would the relative strengths be ranked correctly? 1. LiCl > LiBr correct 2. MgCl 2 < CaBr 2 3. < KCl 4. NaI > LiI Explanation: The strength oF the coulombic interaction between the two ions is directly proportional to their charges, and inversely proportional to their separation. The separation oF the ions is determined by their radii. ThereFore the strongest interactions will be between small ions and with a high charge. 003 10.0 points Which oF the Following ions has a tetrahe- dral molecular (actual) geometry? 1. H 2 ² + 2. NO 3 3. CO 2 3 4. NH + 4 correct 5. H 3 O + Explanation: N H H H H
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Version 092 – Exam 2 – McCord – (53130) 2 For the central atom N, HED = 4 and lone pairs = 0, so the electronic and molecular geometries are also tetrahedral. N H H H H 004 10.0 points A molecule has one lone pair of electrons on the central atom and three atoms bonded to the central atom. The central atom follows the octet rule. What is its electronic arrange- ment and its hybridization? 1. trigonal planar; sp 2 2. trigonal planar; sp 3 3. tetrahedral; sp 2 4. tetrahedral; sp 3 correct 5. pyramidal; sp 2 6. angular; sp 3 7. pyramidal; sp 3 Explanation: One lone pair plus 3 bonded pairs equals 4 electronic regions. This means that the central atom is tetrahedral and hybridization is sp 3 . 005
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test 2 - Version 092 Exam 2 McCord(53130 This print-out...

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