Exam 2-solutions - Version 189 – Exam 2 – Sutcliffe...

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Unformatted text preview: Version 189 – Exam 2 – Sutcliffe – (53770) 1 This print-out should have 32 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. THIS EXAM IS FOR DR. SUTCLIFFE’S T-TH CLASS ONLY!! 001 10.0 points How many lone pairs are on the central atom of ClF 3 ? 1. 4 2. 1 3. 2 correct 4. 3 5. Explanation: The Lewis dot structure for ClF 3 is Cl F b b b b b b F b b b b b b F b b b b b b b b b b , 002 10.0 points N 2 has a bond order of 3 and O 2 has a bond order of 2. Based on this information, choose the response that best completes the following sentence, in the order listed. N 2 is (less, more) stable than O 2 , and has a (larger, shorter) bond length and a (higher, lower) bond en- ergy. 1. more; shorter; higher correct 2. more; shorter; lower 3. less; shorter; lower 4. less; longer; lower 5. more; longer; higher Explanation: The higher the bond order, the more sta- ble the molecule. Stable bonds have a high bond energy since they are hard to break apart. As bond order increases, the bond length gets shorter. Triple bonds have shorter bond length than double or single bonds. 003 10.0 points Which of the following molecules or ions con- tains two π bonds? 1. CH 4 2. NH 3 3. CO 2 correct 4. ClO − 3 5. Cl 2 Explanation: 004 10.0 points Classify the molecule SiBr 4 . 1. polar molecule with nonpolar bonds 2. polar molecule with polar bonds 3. nonpolar molecule with nonpolar bonds 4. nonpolar molecule with polar bonds cor- rect Explanation: 005 10.0 points Which of the following is a polar molecule? 1. CO 2 2. CH 4 3. XeF 2 4. SF 6 5. SO 2 correct Explanation: SO 2 has 1 lone pair on S and two S O bonds. The best structure for formal charge has both bond as double bond. This leaves all three atoms with zero for for- mal charge. The electronic geometry is trig- Version 189 – Exam 2 – Sutcliffe – (53770) 2 onal planar with one lone pair of electrons. This will cause the molecule to be polar. 006 (part 1 of 2) 10.0 points What is the molecular shape of the SbF 2 − 5 ion? 1. trigonal bipyramidal 2. octahedral 3. square pyramidal correct 4. trigonal pyramidal 5. tetrahedral Explanation: The Lewis structure is Sb F b b b b b b F b b b b b b F b b b b b b F b b b b b b F b b b b b b b b 2 − . The shape is square pyramidal based on an oc- tahedral arrangement of electrons about the Sb atom. 007 (part 2 of 2) 10.0 points How many different F- Sb- F bond angles are in this molecule? 1. 4 2. 2 correct 3. 3 4. 1 5. 5 Explanation: There are two types of F- Sb- F angles: 90 ◦ (adjacent) and 180 ◦ (opposite). 008 10.0 points Which of the following is the correct Lewis formula for oxygen difluoride (OF 2 )?...
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This note was uploaded on 03/11/2009 for the course CHEM 301 taught by Professor Wandelt during the Spring '08 term at University of Texas.

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Exam 2-solutions - Version 189 – Exam 2 – Sutcliffe...

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