Exam 3 T Th-solutions

# Exam 3 T Th-solutions - Version 212 Exam 3 T Th sutcliffe...

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Unformatted text preview: Version 212 Exam 3 T Th sutcliffe (50985) 1 This print-out should have 28 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points A gaseous mixture made from 6.00 grams of oxygen gas and 9.00 grams of chlorine gas is placed in a 15.0 L vessel at 10.0 degrees Celsius. What is the total pressure in the vessel? 1. 0.800 atm 2. 0.655 atm 3. 0.488 atm correct 4. 1.00 atm 5. 0.244 atm Explanation: 002 10.0 points Calculate the percent composition of silver sulfate (Ag 2 SO 4 ). Choose the correct per- centages for Ag, S, and O. 1. 65.00% Ag, 10.00% S, 25.00% O 2. 50.00% Ag, 20.00% S, 30.00% O 3. 75.00% Ag, 10.00% S, 15.00% O 4. 28.57% Ag, 14.29% S, 57.14% O 5. 69.19% Ag, 10.29% S, 20.53% O correct Explanation: percent composition of Ag 2 SO 4 = ? 1 mol Ag 107.87 g Ag mol Ag = 215.74 g 1 mol S 32.07 g S mol S = 32.07 g 4 mol O 16.00 g O mol O = 64.00 g Molar mass = 311.8 g/mol 215.74 g Ag 311.81 g AgSO 3 100% = 69.19% Ag 32.07 g S 311.81 g AgSO 3 100% = 10.29% S 64.00 g O 311.81 g AgSO 3 100% = 20.53% O 003 10.0 points Which statement is FALSE about C 2 ? 1. It is paramagnetic. correct 2. It has a bond order of 2. 3. It would be expected to have a shorter bond length than C 2+ 2 . 4. It has four electrons in 2 p orbitals. Explanation: 004 10.0 points In the reaction CH 4 + 4 Cl 2 CCl 4 + 4 HCl , how much methane is required to completely react with 85.6 grams of Cl 2 ? 1. 0.604 mol 2. 0.302 mol correct 3. 4.83 mol 4. 21.4 mol 5. 1.21 mol Explanation: m Cl 2 = 85.6 g The balanced equation for the reaction in- dicates that 1 mol CH 4 is needed for every 4 mol Cl 2 reacted. First we calculate the moles Cl 2 present: ? mol Cl 2 = 85 . 6 g Cl 2 1 mol Cl 2 70 . 9 g Cl 2 = 1 . 207 mol Cl 2 Using the mole ratio from the chemical equation, we find the moles CH 4 needed to Version 212 Exam 3 T Th sutcliffe (50985) 2 completely react 1.207 mol Cl 2 : ? mol CH 4 = 1 . 207 mol Cl 2 1 mol CH 4 4 mol Cl 2 = 0 . 302 mol CH 4 005 10.0 points The following experiment was carried out us- ing a newly synthesized chlorofluorocarbon. Exactly 50 mL of the gas effused through a porous barrier in 172 s. The same volume of argon effused in 76 s under the same condi- tions. Which compound is the chlorofluoro- carbon? 1. C 2 Cl 2 F 4 2. C 2 Cl 4 F 2 correct 3. C 2 Cl 5 F 4. C 2 ClF 5 5. C 2 Cl 3 F 3 Explanation: 006 10.0 points In the molecule, C 2 H 4 , what are the atomic orbitals that participate in forming the sigma bond between the C and H atoms? 1. H: 1 s and C: 2 p 2. H: 1 s and C: sp 2 correct 3. H: sp 2 and C: sp 2 4. H: 2 p and C: sp 3 5. H: 1 s and C: sp Explanation: The electrons in the H 1 s orbital and the electrons in the C sp 2 hybrid orbital partici- pate in forming the bond....
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## This note was uploaded on 12/11/2010 for the course CH 301 taught by Professor Fakhreddine/lyon during the Fall '07 term at University of Texas at Austin.

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Exam 3 T Th-solutions - Version 212 Exam 3 T Th sutcliffe...

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