Exam2 - Version 303 Exam 2 Sutcliffe (53120) 1 This...

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Unformatted text preview: Version 303 Exam 2 Sutcliffe (53120) 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 ONLY for students in the MWF 2-3pm section!! 001 10.0 points Which one has the greatest number of atoms? 1. 3.05 moles of argon 2. 3.05 moles of water 3. All have the same number of atoms 4. 3.05 moles of helium 5. 3.05 moles of CH 4 correct Explanation: For 3.05 moles of water: ? atoms = 3 . 05 mol H 2 O 6 . 02 10 23 molec 1 mol 3 atoms 1 molecule = 5 . 51 10 24 atoms For 3.05 moles of CH 4 : ? atoms = 3 . 05 mol CH 4 6 . 02 10 23 molec 1 mol 5 atoms 1 molecule = 9 . 18 10 24 atoms For 3.05 moles of helium: ? atoms = 3 . 05 mol He 6 . 02 10 23 atoms 1 mol = 1 . 84 10 24 atoms For 3.5 moles of argon: ? atoms = 3 . 05 mol Ar 6 . 02 10 23 atoms 1 mol = 1 . 84 10 24 atoms 002 10.0 points If a molecule has square planar molecular ge- ometry, what must be its hybridization? 1. sp 3 2. sp 3 d 2 correct 3. sp 2 4. sp 5. sp 3 d Explanation: A molecule with square planar molecular geometry has octahedral electronic geometry which cooresponds to sp 3 d 2 hybridization. 003 10.0 points How many non-bonding electron pairs are around I in IF 2 ? 1. 2. 3 correct 3. 2 4. 4 5. 1 Explanation: Iodine has seven valence electrons. Flourine has seven valence electrons. Each flourine atom will form a covalent bond by sharing one of iodines electrons. This leaves iodine with 5 electrons plus the additional electron that gives the molecule a net negative charge. That makes six non-bonding electrons around iodine, or three pairs. I F b b b b b b F b b b b b b b b b b b b 004 10.0 points For the electron dot representation N O O O N O O 2 4 1 3 Version 303 Exam 2 Sutcliffe (53120) 2 of N 2 O 5 , what are the formal charges on each atom going from 1 to 4 in order? 1. 0, 1,- 1, 0 correct 2. 1, 0, 1, 0 3. 0, 0, 0, 0 4.- 1, 2, 1, 0 5. 0, 1, 0,- 1 6. 1, 1, 0,- 1 Explanation: The formal charge is calculated by FC = group #- (# bonds + # unshared e ) Thus FC 1 = 6- (2 + 4) = 0 FC 2 = 5- (4 + 0) = 1 FC 3 = 6- (1 + 6) =- 1 FC 4 = 6- (2 + 4) = 0 005 10.0 points On the usual Pauling scale of electronegativi- ties, the electronegativity of Selenium (Se) is 2.4, while that of chlorine (Cl) is 3.0. Based on these values we should expect the bonding between Se and Cl to be 1. covalent and nonpolar. 2. unstable in any circumstances. 3. covalent and polar with the Cl end of the bond slightly negative. correct 4. ionic. 5. covalent and polar with the Se end of the bond slightly negative....
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Exam2 - Version 303 Exam 2 Sutcliffe (53120) 1 This...

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